Y Block Help Needed

[countrysquire]

I hope I'm posting this in the right forum, please move it if I have it in the wrong place.

I just picked up a '55 Thunderbird that was restored a few years back, but has been sitting for the last year or so. Once I got it started, there was a pretty healthy gasoline leak from the pump, no doubt caused by the upstream electric pump. With the electric fuel pump disconnected and a new stock pump in place, it's running again, but it doesn't idle well. New plugs to replace the fouled ones didn't help a lot. I connected a vacuum gauge and it is between 10 and 11 inches hg, which seems awfully low. The timing seems to be advanced well beyond the 6 or 8 degrees that it should be, but retarding it makes it worse. When you rev it, it seems smooth and as powerful as you would expect, with vacuum in the 22-24 range.

The previous owner kept receipts of all the work that had been done, and it looks like a couple shops have tried to resolve similar issues with it. There has been a valve job with the heads resurfaced, new intake gaskets, carb overhaul, Pertronix ignition, etc. Compression is a little low, but consistent at 105 psi or so. The valves were set a little loose, so I reset them at .020 but that seemed to make the vacuum drop an inch or so. There is zero blow-by and no evidence of oil on the plugs, so I think that the rings are good.

Finally, sometimes it will idle as long as you like at 7-800 RPMs and is almost acceptable. Other times, one of the secondary barrels fills with fuel, eventually killing it by flooding. It has the original Holley 4000 teapot carb, which I have no experience with.

Anyway, it strikes me as having a vacuum problem that no one has been able to find as well as a carburetor issue. This is my first Y block, but I wouldn't think that it would be much different than diagnosing any other engine. That said, it's kicking my butt and I'm having to reach out to the experts.

Any help is appreciated.

Thanks,
Bobby

[Charlie Stephens]

Long shot, any of the plug wires mixed up? It is rough to work on a car when you don't know what was changed last.

Charlie Stephens

[countrysquire]

Thanks Charlie, I'm headed out to check that now. Maybe they did it in the newer 15426378...

I'm experimenting with things, and it looks like when the secondary butterflies open that's when it fills with fuel and kills the car. I don't know if this is because of the vacuum issue or not.

I just took it for a four mile ride at about 50 mph and it's missing at all RPMs. Placing it in 'Drive' knocks the RPMs from about 800 to 450 or so, barely enough to keep it running. I pulled the valve covers back off to make sure that all the rockers were moving as they should, and that looks good, but I haven't gone as far as doing any measuring. Also, there's a receipt for pulling the timing cover to check the timing chain, so I *assume* that is good. Still checking and looking and appreciate the help.

[scicala]

If you actually saw fuel filling up one of the rear barrels of the carburetor, then I would say you have some type of issue with the carburetor. There is a short brass tube that goes from the throttle body to the float bowl that has an o-ring on each end. A common place for leaks that could fill the one rear barrel.
Have you tried to adjust the idle mixture with the two screws on the front of the carb at the base ? See if the vacuum increases. Other possibility could be a vacuum leak somewhere. Even if the ignition timing was 20 degrees BTDC at idle, this would not cause low manifold vacuum.
If it comes down to the carb, I just finished restoring a correct original one for a 1955 Thunderbird. A rare carb though because it's a different part number than the passenger car carb.
Let me know if interested. Sal Cicala

[countrysquire]

Since the last post, I have reran the valves to make sure that they are at .020 and done a compression test. All the cylinders were between 112 and 128. Not high, but I would like to think it's enough to pull more than 9 inches of vacuum. What I keep thinking about is the timing. The marks on the balancer run from TDC to 10 degrees (I think). However, it wants t run at about 2.5 inches past that, which I would estimate about 25-30 degrees. Advancing it from there makes it ping, retarding it to the specified 8 degrees makes it feel very sluggish. When it's at TDC per the balancer, the rotor is pointed right at #1. One of the shops that worked on it pulled the timing cover to verify that timing hadn't jumped. Still, it sure makes me think that the cam is not synced up with the crank like it should be.

[40cpe]

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The cam and crank marks are a certain number of links apart on the timing chain. I wonder how many shops understand that. It won't run with the marks lined up with each other, so maybe they got it right.

[Tinker]

Clean your plugs, run the crap out of it and shut it down quickly. Pull the plugs and look at them.

My understanding is that y blocks like advanced timing. My initial right now is around 12+ degrees, 35 advanced. This is after taking it down some. 57 292.

***at lunch today I put a light on the motor. I was a little off on my numbers, 8 initial and 35 full advance. After I get all the wiring done I will have to play around with the retarding the timing and see how it runs. Have driven it and it hauls a$$ with this setting***

You want about 18" vacuum. Check leaks, set timing advanced some, adjust carb to best vac, then adjust timing again.

It sounds like you have decent compression. I would look at the carb or you ignition system and timing.

One last thought is the 55 distributor and advance. Search it a bit.

[Tinker]

Another thing you might want to do is make sure tdc and the marks on the pully actually match up. They do slip over time. There are ways to do this without pulling the head by using rope or a piece of tie wrap. It will not be 100 percent but you will be able to see if it has slipped 10 degrees or more.

Best of luck.

[countrysquire]

Thanks. I pulled the plugs after driving it and they looked good, nothing fouled like you might expect with a dead cylinder. Also, the balance is new (they charged the previous owner $350 for a new balancer!!), and when it is at the TDC mark, both of the rockers on #1 cylinder are 'loose' and the rotor is pointed at the #1 wire.

[darrell]

I would think the trouble remains in your carb.take it apart and blow out the passages and check for broken gaskets o rings etc.if you have power brakes plug the hose as well as wiper hose to see if you have a vacuum leak first.

[countrysquire]

Would a carb issue cause the vacuum to be half of what it should be? I'm thinking that I have an issue in addition to carb trouble.

I'm still puzzled why the the timing has to be so far advanced for it to run. I had mentioned before that when the previous owner had it in a shop (foreign car shop, don't know how much they know about Y blocks) that they pulled the timing cover to check it. It could be that they were expecting to see the two dots on the gears lined up, which I understand is not correct for a Y block. So it may or may not be right. That said, with the balancer at the TDC mark, both of the rockers on the number 1 are loose, so the lifters must be pretty close to the bottom of the cam lobe. Also, when at the TDC mark, the rotor is pointing to number 1 on the distributor, but I guess that you can stab the distributor in any orientation.

I'm going to pull the rocker shafts this morning to make sure that none of the pushrods are bent. They spin freely when relaxed and all the valves look to travel as far as you would expect when the cam turns.

[Ole Don]

Congratulations on becoming a Y block owner. A Y block is like any other engine, it needs compression, fuel and fire to run. Looking for a high vacuum reading with an unknown cam is futile. My car idles at 11 inches, on a good day. The cam is Iskenderian, I love it.
Any Y block runs better when timed with a vacuum gauge or by ear. Correct cam timing is, when looking at the cam drive, the colored links, or dots, should both face to your right, with 13 pins between them. If it runs down the road, that part is correct.
Early solid pushrods bend easy. Straighten them with a hammer on a hard surface.

[countrysquire]

Thanks Don. It does run down the road and doesn't run horribly like if the cam was way out of time. Fact is, if it ran great I would have never put a gauge on it. No idea what kind of cam is in it. I'm about to check all of the pushrods and then adjust the valve lash again. .020" cold is correct, right?

[Y-Blockhead]

I agree with everything Ole Don said with the exception of the push rods. I would recommend if you find bent solid push rods to go ahead and replace them with new tubular ones.

I have a Clay Smith cam in my 312" and I can't even come close to stock timing specs.
It idles best at ~14 inHG and when checked with a light it is at 16° BTDC. One thing to remember when running this much 'initial' advance is to check and limit your 'total' advance.

[Tinker]

I want to say it is 12 pins not 13 on the timing chain.

[Tinker]

If your rockers are worn a little you can use the quarter turn method. Tighten to zero lash, then backoff a quarter turn.

http://www.jalopyjournal.com/forum/s...d.php?t=521955

[countrysquire]

Update: Pulled the rocker shafts and ensured that all of the pushrods are straight. Reset valve lash at .019" with everything cold. Started back up and valves were quieter, but vacuum now in the 7-8 range. The previous shop had it set at .035", maybe in an effort to increase the vacuum, not sure. Anyway, it still has the same miss. I did notice that the rotor had a ton of play (the shaft itself seemed fine), so I will see if I can find another rotor that fits better.

I did make a discovery that will hopefully lead to a solution. I scanned all of the inlet ports on the exhaust manifolds and realized that there's a problem with #5 & 6 cylinders. The other six cylinders were between 400 & 425 degrees, while #5 was about 190 and #6 was 285. Both cylinders were getting good spark and the plugs were not fouled when I pulled them yesterday. Compression of both cylinders were in the same range as all the others, so I think the issue is that that corner of the engine is not getting enough fuel for combustion to occur. That has to point to either a carb or intake issue, I would think, but would sure like some other opinions.

Thanks again for all of the advice.

[countrysquire]

Oops, the dreaded double post.

[countrysquire]

Did a test for vacuum leaks this afternoon with a homemade smoke machine, but didn't see anything leaking. I'm going to pull that valve cover again and watch the rocker movement on #5 closely.

[JeffB2]

Originally Posted by Tinker

If your rockers are worn a little you can use the quarter turn method. Tighten to zero lash, then backoff a quarter turn.

http://www.jalopyjournal.com/forum/s...d.php?t=521955

Y-Blocks are solid lifter cams,that only flys with hydraulic lifters.Zero clearance and solid lifters =

[countrysquire]

OK, the issue on 5& 6 is solved. I seemed to swap those two plug wires when i reassembled it this morning. I meant to do a continuity test then, but got sidetracked and forgot. Vacuum is back in the 11 range, but it has a bunch of initial advance. When I crawled underneath to investigate an exhaust leak, I did notice that the rear main seal is leaking badly and there's a good bit of smoke vapor coming from the road draft tube, which makes me think it must be seeing a lot of crankcase pressure. Not good.

[paul2748]

Could be some bad plugs. Just because the plug is getting spark doesn't mean they are firing.

[Y-Blockhead]

Originally Posted by JeffB2

Y-Blocks are solid lifter cams,that only flys with hydraulic lifters.Zero clearance and solid lifters =

I think Tinker is referring to Walt Nuckels' method of adjusting Y-Block valves… http://www.y-blocksforever.com/tech/html/valvelash.html

[Tinker]

Makes perfect sense if your rocker arms are worn. If there is any groove the feeler gauge is worthless.

Being that we have no idea about the condition, cam, etc. it would get you in the ballpark.

[Y-Blockhead]

Even works on new rockers…

[countrysquire]

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Thanks for the suggestions and continued support.

• I have been checking the vacuum by disconnecting the line that runs from the intake manifold to the fuel pump and attaching my gauge to that line.
• I have blocked off the brake booster, no change.
• I have disconnected the vacuum line to the distributor and didn't see a change. When connected, the timing does advance with RPMs.
• The mushroom shaped diaphragm on the side of the carb seems to move in about 1/16" or so when revved.
• Vacuum is idle speed and ignition advance dependent. Initial advance is somewhere around 25 degrees. With the idle at ~750 RPMs, vacuum is ~7"hg. At 1000 RPMs vacuum is between 10 & 11"hg.
• Placing the car in gear will drop the idle from 1000 to about 450, barely enough to keep running.
• All the valves look to be opening the amount, but I have not measured yet to see if they are within spec.
• The car seems to run best at ~25 degrees initial advance. Move it much further and it detonates under a load, retard it and it's really sluggish.
• When the car is idling, there's a steady stream of fumes coming from the road draft tube. Is this normal?

I haven't checked compression since I have adjusted the valves, but plan on doing that this evening. Also, I will do a dry and wet compression check to see if it's a piston ring issue. The first test I did was dry and the cylinders were all in the 110-128 range.

At this point, I think that the problem is either the camshaft orientation or an issue with the rings.

The motor looks like it's been rebuilt (I know that the heads have been), but that doesn't mean anything. Maybe the engine assembler installed the rings wrong, or maybe they are all stuck because the car has done a lot of sitting after its restoration. Or maybe it was only painted and not rebuilt.

The fact that it needs so much advance makes me think that the timing set may have been installed wrong. A previous shop had pulled the timing cover to inspect this, but it's a foreign car shop, so their Y block experience is probably very limited. It could be they were looking to find the dots on the gears lined up at 6 & 12 o'clock like every other V8 that I've ever worked on. If I understand correctly, the dots on the gears should both be around 3:00 with 12 links between them.

Sorry for the long post, but I wanted to keep those of you who have been helping me up to date.

Thanks again,
Bobby

[streetdreams]

sure the distributor vacuum diaphragm isn't cracked and/or not functioning? I would think you would see some spark advance response with the vacuum line on, and then disconnected. I had a Yblock in here a couple years ago where it ran like crap, and several shops tried to sell him a carb. It was a failed vacuum diaphragm in the distributor, and a well stretched timing chain.

[countrysquire]

I haven't watched the timing advance with the advance disconnected, but will try that. Vacuum readings did not change with the distributor line disconnected. I don't like the poor fit of the rotor on top of the distributor shaft, but would assume that centrifugal force would keep it in the same position while the engine is running.

[darrell]

theres a clip missing from your distributor where the rotor sits that keeps it tight.

[countrysquire]

I don't remember seeing any clip. I wonder if it went away when they installed the Pertronix.

[Ole Don]

Some vapor is normal at idle from your road draft tube. The reason you don't see it on newer engines is because they eat it. Its fed into the intake through the PCV. A modern PCV is easy to put on your engine after you are satisfied with its running.
Pertronix adjustment; the instructions on mine said the pickup coil should be set at .020 with a non magnetic feeler. I messed around the shop looking at stuff and settled on a double thickness of the clear plastic from a bubble wrapped part. Check NAPA to see about a new rotor and clip. New spark plugs are called for with your problems. I have the best luck with NGK brand, gapped about .030 to .035.
To free up stuck rings, add a quart of ATF and go for a fifty mile ride and back at highway speeds. Change oil and filter to anything with 40 or higher as part of the number.

[countrysquire]

Thanks Don. Here's a video of it running. The valves are not nearly as loud in person as they are in the video.

https://www.youtube.com/watch?v=vOMI_...ature=youtu.be

[Tinker]

Nice looking car and it sounds great. What are you running as far as mufflers?

Here is a vacuum gauge chart for you.

[countrysquire]

Thanks. I haven't gotten as far as investigating what kind of mufflers are on it, but I do know that at least one of them is leaking...lol.

[kari 613]

I think that Mac's ford parts in Lockport NY. has that small dist. shaft clip. I just replaced my rotor and couldn't find one with the little button on the top contact tab like the original rotor had. My flat spot on my rotor was worn where it fits on the dist. shaft. A new rotor helped. Maybe you could borrow another good carb to see if the carb is your problem.

[Ole Don]

Two things pop out of that movie, it idles like it has a fairly wild cam, that may be its best idle. Two; if you have adjusted the rockers, you may have worn rockers and will never get them quiet. Some machine shops may not know about refacing the rockers. There are movies on youtube showing how its done. One Y blocker I know made his own fixture to do his at home.
Another thought, the rocker clearance is written in the book as .019. My after market cam company says they can be looser, to mellow out the engine, or tighter, to add dwell duration and lift. It can go all the way from .012 on the tight side to .028 on the loose side.

[Bruce Compton, Canada]

I agree with Sal, in that you probably have a carb issue. Apparently these carbs are fine if they are set up by someone that knows what they are doing, and I believe that Sal does. You also my want to check for a manifold to head leak, or carb to intake leak to explain the low vacuum reading. Bruce.

[scicala]

Originally Posted by Ole Don

Two things pop out of that movie, it idles like it has a fairly wild cam, that may be its best idle. Two; if you have adjusted the rockers, you may have worn rockers and will never get them quiet. Some machine shops may not know about refacing the rockers. There are movies on youtube showing how its done. One Y blocker I know made his own fixture to do his at home.
Another thought, the rocker clearance is written in the book as .019. My after market cam company says they can be looser, to mellow out the engine, or tighter, to add dwell duration and lift. It can go all the way from .012 on the tight side to .028 on the loose side.

I agree with Ole Don in that the exhaust sounds like it has a fairly stiff camshaft in it. That doesn't sound like a rough idle from not running good. It sounds like it's from cam overlap. If that is the case, it would explain the lower vacuum. More overlap will reduce manifold vacuum. However, if the engine actually runs rough or performs poorly, it could be other issues like the carb.

[countrysquire]

Well, tore off the front end and didn't find what i was hoping to find. The timing is oriented as it should be, so I guess that means it's the rings. I had been contemplating pulling the engine anyway to repair leaks and freshen up the restoration, so why it's out why not freshen up the engine so that I know what I have.

[Tinker]

Rings in relationship to compression?

My thoughts are: Fix the carb, adjust the valves or have your heads rebuild ( fluttering vacuum reading suggest valve guides or valves) i would do this before going for the rings. And if it turns out to need a full rebuild you will have a good carb and heads ready to bolt on.

Just a thought.

[countrysquire]

Thanks Tinker. The heads have been rebuilt not long ago, so I'm assuming they are good. That said, if I pull it apart, I will check the heads as well to make sure that they are right.

[Bruce Compton, Canada]

A couple of things about this post have me wondering. You mentioned that the "mushroom shaped" valve on the carb can be seen moving in 1/16th when the RPM is increased, but any spark control valve I've ever seen is built in a way that you can't easily see the diaphragm. Is it possible that someone has installed a power valve instead as they have the same thread and look similar? The other thing is that you have stated that the initial timing is set at 25 degrees, and I'm wondering why it does'nt kick back on the starter with that much initial. Also, if the distributor is the original loadamatic, you will have no advance with the vacuum line disconnected as there is no mechanical advance provision. I still think your problem is either the carb or intake manifold. Good luck : Bruce

[wellcraft17]

A number of years ago I had the exact same issue as you with a new rebuild with all new parts on a stock Y block. Would not idle right, low compression and low vacuum. I rebuilt it myself so I knew it was put back together correctly. Drove me nuts for over a month and one day an old Ford mechanic told me to reset the intake valves to .035 or .045 and see if it runs any better and if the compression and vacumm would come up. Well it ran alot better and the compression and vacuum did come up significantly. He then told me I had a bad camshaft! This was a new camshaft that I installed at the rebuild from a reputable company. I removed the shaft and sent it to a another well known camshaft co. to be checked. They called me and told me that the intake lobes on the cam had not been properly ground at the factory and that was causing all my problems and it would never run right the way it was. They reground the cam, I reinstalled it and it ran perfect. Compression came up to 165 on all cyls and the vacuum came up to 22. The machine shop that did all machining for me said they could only remember one other time they had encountered a bad cam in the 60+ yrers they had been in business. Hope this is not your problem but the symptoms are very similar.

[darrell]

I came across this twice first time it was a 454 that came into the garage where I worked.we worked on it for days of and on the motor had been heated and rebuilt.the valve springs were collapsed.whoever rebuilt the heads never saw it.i rebuilt a 351m for my sons truck I had a parts engine from a cube van the cam looked like new and mine was just fair so used it.like you I had 11 vacuum.tried everythink under the sun in the end it was the cam.it was a ford cam and I never found out what it was used in.it was a pig in the truck and I cant imagine what it was like in a cube van.

[countrysquire]

I have to drop off the starter at the rebuilder today, but when I get it back, I will try a compression test with the intake valves set around .040" and see what happens. I don't know any other methods to test for a wrong cam, but I'm certainly open to suggestions. I've built a couple engines with a fairly big cam, and while they have a 'lope', they don't shake like this one does. It's just not quite right.

[wellcraft17]

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The only way that I know of checking the cam in the engine is to degree it in with a degree wheel, when I did that before shipping mine off to be checked I found that the intake valves were closing at different degrees of crankshaft rotation on each cyl causing an eratic running engine. Degreeing a cam is a pain in the rear and time consumming and requires special tools. Looking at your picture of the timming chain it appears to me it has a fair amount of slack/play in it and if so I would think that engine has not been rebuilt recently. If it has been rebuilt recently someone might not have replaced the chain when it was apart thinking it was still ok. One other check of the cam would be to check the lift of the cam lobe with a dial indicator at the rocker arm or the tip of the push rod, this would tell you if a lobe is worn down.

[countrysquire]

Thanks Wellcraft. I have a degree wheel and dial indicators, so I will work on that while I'm waiting for my starter to be rebuilt.

[darrell]

how I checked the cam on the 351 before I tore it down was to check when the intake valve starts to open.you have to have a tight timing chain to get it right since mine was new it was no problem.you insert a feeler gague on number 1 cyl,intake valve and turn the engine over slow until it pinches the gague needs to be close fit so it will catch the second it moves then read your degrees on the damper pulley.intakes open on most stock around 18 degrees a tuneup manual will tell exactly.my 351 cam opened at 30 so I had my answer.

[countrysquire]

That makes sense Darrell. I will see if I can find the info on where the valve should be opening on a stock cam.

[Tinker]

Since you have the front tore down you might as well replace the timing chain, it does look worn as mentioned. That is unless your going to pull the engine and do a freshening of the engine :].

Best of luck.

[countrysquire]

I will definitely replace the chain while I'm in there. Thinking out loud, I will probably check with the degree wheel before and after the new chain.

[darrell]

found my old chiltons repair manual.its 12 degrees beford tdc on a y block.

[wellcraft17]

As it relates to compression and vacuum it's very important at what degree the intake valve closes because if it closes to late essentially you are pushing the intake charge back out the intake manifold as the piston starts up to TDC. And to compound the problem if all the intake lobes are not the same you have a fluttering vacuum and erratic compression.

[Bruce Compton, Canada]

After all this discussion, this may sound like over-simplification, but I'd be pulling the intake manifold and making sure that the previous builder used the correct gaskets. All 1954 and some '55 heads/intakes had much smaller ports and if you used the later '56 and up intake gaskets you would almost certainly have vacuum leaks. Bruce

[jim galli]

When I was a kid, dating, I had a '55 'bird. We're talking 1972, and I'm still not over that car, but that's another story. Stick and overdrive. One night at my girlfriends house (still have the girl, car long gone) I started as normal and got a funny backfire. Thinking I'd just let go of the key too quick, I re-tried, and when it started, since I'm a Model A guy, I knew immediately it was running way retarded. So I got a wrench and advanced the timing and headed for home, about 20 miles away. Long story short, I knew what was going on with the timing chain, and I had to stop 2 more times on the way home and advance the ignition. Obviously with 3 teeth off, it was running really rough by the time I got it home, but, it got me there fine. Next day we replaced the chain and off we went as good as new.

Good luck on the T-Bird. Wish I had one. 2 Model A's and out of $$$ and space.

[countrysquire]

Thanks Darrell, I've ordered the shop manual, but it won't be here for another day or two.

Bruce, I agree that it seems like it could have a bad vacuum leak at the intake, but I tested with propane and carburetor cleaner with it running, then followed up with a smoke test and could find no signs of any leak.

Jim, though I don't own one right now, I'm a Model A guy too and know what you are talking about. Anywhere near the specified 6-10 degrees of initial advance, this thing definitely feels retarded. You have to get into the 40+ range before it gets too advanced, making it difficult to start.

[Tinker]

This is a nice online reference for yblocks.

http://www.ford-y-block.com/technical.htm

http://www.ford-y-block.com/tuneup.htm

On a side note, you have to disconnect and plug the vacuum advance when testing for your initial advance. You may have done that and you have bigger fish to fry now anyway.




.

[countrysquire]

Awesome, thanks.

[wellcraft17]

Keep in mind this engine only has an avg.105 lbs. of compression. Per the book min psi for this engine is 130lbs. With that in mind there are four key areas that can cause this, bad pistons/rings, bad valves, bad valve timmimg, and bad cam. Yes there are a few other areas that could have an impact like blown headgasket but that would have already been discovered,ie, water in oil/oil in radiator, very low compression on several cyls. A bad intake gasket would have no impact on compression, just think of it this way, what if the intake manifold was not bolted to the engine and you do a compression test. The reading would be the same with the manifold off or on unless there was a major obstruction inside the manifold that could not be seen.

[countrysquire]

Wellcraft, all good points, and that's why I was expecting to see the cam oriented wrong when I pulled the front cover last night.

I have a receipt for the reconditioning of the heads, due to drivability issues, so I'm going to rule out a valve or head issue for now.

With worn rings, I would be expecting smoke out of the tail pipe and blow-by from the breather, and I have none. They may not be perfect, but I don't think they are bad enough to make it run poorly. Plus, I wouldn't think bad rings would cause the timing to have to be that far off.

The timing chain has some wear, but it looks to be within the Ford spec of 1/2" of play. Not ideal, but I don't think that it would make the vacuum 1/3rd of what it should be. I could be wrong about that though. It will get a new timing set regardless of anything else that is found.

That leaves me with the cam, opening and closing the valves at the wrong time. Based on receipts, several mechanics have tried to solve this, but no one has. I do not see where anyone has gone as far as actually checking the cam. A bad or wrongly ground cam seems like a long shot, but what else is left?

I know that it's sure nice having the help of the Ford community.

Bobby

[Hot Rod Reverend]

Don't know if this has been covered yet but a quick way to check out that cam would be to remove both valve covers, start the engine and watch both banks as the valves operate. It should not take too long to notice anything out of whack (like an intake valve not moving up and down, etc). The only thing that would be hard to check here would be the actual timing of the intake/exhaust event as it relates to the rest of the cylinders...

Anyone have an old Sun Machine he could borrow?

[wellcraft17]

I agree with your process of elimination as that's exactly what I went through and for someone to tell me I had a new camshaft that was bad was inconceivable and unheard of. I'm not saying this is definately your problem but there is not much left. After thinking about this for awhile I'm assuming you do not know the history of this engine and I'm wondering if the engine ran hot and cooked the rings but you indicated there's not any blow by. What else can be left? Solve your compression problem and it will eliminate a lot of other areas of concern you may have. One check of the rings you could try, and I have not seen this pop up on this discussion, is squirt some oil in each cyl. and recheck the compression. If there is a large increase in compression you probably have ring issues. If the engine had sat up for a very long period the rings could have frozen to the pistons, you could try something like sea foam to free them up but that would probably be a long shot.

[swedishsteel]

We bought a '55 bird a couple summers ago and it has/had a similar problem--cruising at road speed it had a very slight but distinguishable miss/flutter. It acted like a vacuum/spark advance leak to me but couldn't find the source. With the used parts we received along with the car is was obvious the previous owners had been trying to diagnos the problem. This winter we decided to pull the engine to replace the badly leaking rear seal and restore/clean the engine bay. When I disassembled the motor I noticed the gasket between the intake manifold and the thermo choke assembly was gone. The engine has been rebuilt and apparently that gasket was overlooked on reassembly. I don't have it back in the car yet, but I suspect that missing gasket could have been leaking vacuum and caused the uneven firing. Hope you find something simple like that. Good luck. Rod

[Oldmics]

Have not seen anyone mention a leak down test.
Are you in a position to preform that proceedure?
That would certainly address the compression/sealing questions.
Oldmics

[countrysquire]

I was helping my son with his car last night, so no updates other than I did check the timing chain and the play was 5/16".

I do plan on doing a leak-down test as part of my testing to decide how far to go while I have the motor out. That said, I'm on the slippery slope of "while the motor is out, why not do X". The time and expense of pulling it all the way down while it's on the engine stand is not great. If the cylinders are within spec, a simple hone and new set of rings is simple enough. Testing should tell me if I need to go that far, but my preference would be not to pull the heads and pistons if I don't need to. I will be installing a new timing set, and probably a new cam and lifters. We'll see what more testing tells me.

[Ole Don]

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On a Y block, the lifters go in from the bottom. The easiest way to replace the cam is with the engine on a stand, upside down, with the oil pan off. A grappling tool is used to pick the lifters out of their holes. Do NOT toss the lifters out. They have no moving parts, they can be reground and used again.

[Bruce Compton, Canada]

Bobby : I can't believe that you're thinking about removing and tearing down the engine before doing the most obvious check first. I've read and re-read all four pages of this post and lots of very informative input has been forwarded and may still have to be applied if necessary, but lately everyone seems to be focused on a camshaft problem. Your very first post stated that the engine was rebuilt, and the work done by a shop not familiar with Y blocks so I'd guess that there is probably an 80 percent chance that they used the later, and much more common intake gaskets. Right from your first post, all the symptoms including the vacuum gauge test point to an intake or carb vacuum leak. Both early and late intake sets LOOK very similar but are NOT interchangeable. The port size on the early Y block heads and intakes are about 3/16ths smaller in both directions, but either set of gaskets will appear to fit. You also stated that the heads were milled, which would also contribute to any misalignment issue. If the wrong gaskets are there you could have eight small vacuum leaks that would be difficult to discover with a propane test, especially the four bottom ports. You have already gone to a lot of work (removing the timing cover and adjusting the valves) in chasing this problem, so do yourself a favor and pull the intake. It's going to have to come off anyway even if the correct gaskets are there. Good luck (again) : Bruce

[countrysquire]

Thanks Bruce. I will definitely be pulling the intake and resealing it, and appreciate the advice about the proper gaskets.

[countrysquire]

Well, hmmm. OK. Had a little time this evening to look at the motor a little more. The dots on the cam & crank gears were at 3:00 with twelve pins between them, just as in the picture from a couple days ago. Used a piston stop and found exact TDC, then installed the degree wheel. Popped of the valve cover and noticed that the valves on #1 weren't loose, so the engine was on the exhaust stroke. Turned it 360 degrees and the cam gear dot was at 9:00, as you would expect. When I popped the distributor cap, I see that it was 180 degrees from #1. Turned it again to get the rotor pointed at #1 and that leaves the cam gear dot back at 9:00.

Can you install the cam in a Y block 180 out, or is it only possible to install the distributor that way, like on other motors? Either way, how could it run this good with something 180 out?

[countrysquire]

Am I correct in thinking that the rotor should be pointed at #1 when #1 is at TDC on the compression stroke (both valves closed)?

[Y-Blockhead]

Check your plug wires. Sounds to me that they just moved the plug wires on the cap to 'compensate' for their 'mistake'.

Now would be a good time to make it right but I don't believe that would change the way it runs…

[40cpe]

Originally Posted by countrysquire

Am I correct in thinking that the rotor should be pointed at #1 when #1 is at TDC on the compression stroke (both valves closed)?

Yes, the dist rotor should point to the plug wire that fires #1 cylinder when the #1 cylinder is at TDC. It doesn't matter where on the cap the wire is located as long as the firing order is correct.

[countrysquire]

Thanks. When standing at the passenger fender looking down at the distributor, should number 1 be at approximately 7:00?

[Bruce Compton, Canada]

Is this a trick question?

[countrysquire]

No trick question. That is how the cap fits, just trying to confirm everything and work on as few assumptions as possible.

[40cpe]

I have a Motors Manual, that is the position shown in the diagram. The clip for the cap is between #1 and the #5 wire, which is at the 6 o'clock position.

[Tinker]

https://www.fordbarn.com/forum/showthread.php?t=87855

http://www.vanpeltsales.com/FH_web/f...eup54-59V8.htm

[countrysquire]

Thanks. I've looked at the flathead info on Van Pelt's site a hundred times, but never noticed any Y block stuff.

[Tinker]

Really its about the tdc of 1 cyclinder and the rotor pointing at the 1 post. If a desired postion of the dizzy is needed or wanted. Pull it out and move it till it lines up. Can be a bear to line up the oilpump rod to the dizzy but you should be fine. On 57 and later y blocks the shaft is a hex, not sure what the earlier shafts are, maybe slotted.

[darrell]

you do know number 1 is on pass,side

[countrysquire]

Yes, 1,2,3,4 on passenger side. Isn't that true of all Ford V8s?

[darrell]

yes but sometimes people get thrown by the fact that cylinder is not the real front one.the flathead is the same.only old henry could come up with a firing like that.ford firihg orders really make no sense.

[countrysquire]

Cam overlap on all cylinders is the same, and it's about 5 degrees earlier than TDC. Also, it looks like there's about 2 degrees worth of slack in the chain. I wouldn't think that's enough to cause compression and vacuum issues. 6" of vacuum is pretty piss poor for a stock cam. I checked cylinder by cylinder per the firing order, 90 degrees at a time and the overlap followed on the cylinders per firing order. Measurements were taken with a metal ruler across the valve retainers, giving me two contact points on each valve.

When turning the engine by hand, you can hear the air blow into the oil pan pretty easily. Maybe the rings ain't as good as I hoped, but my experience doing that has been with new engines that I've built, so I'm sure they are tighter. I've not done a leakdown test yet, but I guess that will be next.

[countrysquire]

Cam overlap on all cylinders is the same, and it's about 5 degrees earlier than TDC. Also, it looks like there's about 2 degrees worth of slack in the chain. I wouldn't think that's enough to cause compression and vacuum issues. 6" of vacuum is pretty piss poor for a stock cam. I checked cylinder by cylinder per the firing order, 90 degrees at a time and the overlap followed on the cylinders per firing order. Measurements were taken with a metal ruler across the valve retainers, giving me two contact points on each valve.

When turning the engine by hand, you can hear the air blow into the oil pan pretty easily. Maybe the rings ain't as good as I hoped, but my experience doing that has been with new engines that I've built, so I'm sure they are tighter. I've not done a leakdown test yet, but I guess that will be next.

[countrysquire]

Finally had time to do a cam timing check this afternoon, and here's what i came up with:

Intake valve opens at 29° BTDC vs. Ford spec of 12° BTDC
Intake valve closes at 85° ABDC vs. Ford spec of 54°ABDC
Exhaust valve opens at 89° BBDC vs. Ford spec of 58° BBDC
Exhaust valve closes at 41° ATDC vs. Ford spec of 8° ATDC

All opening and closing measurements were taken at .020" to compensate for valve lash, dial indicator inside of pushrod cup.

The intake lobe center angle came out to 112°.

Intake valve lift measured .278" (.298" - .020") vs. Ford spec of .264"

Exhaust lift measured .281" (.301" - .020") vs. Ford spec of .262"

[countrysquire]

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Dang double post...

[Tinker]

Itll be interesting to see what happens with a timing gear and chain change. If your doing that in lieu of a total rebuild.

[darrell]

time to pull the cam and see what you have.

[scicala]

Originally Posted by countrysquire

Finally had time to do a cam timing check this afternoon, and here's what i came up with:

Intake valve opens at 29° BTDC vs. Ford spec of 12° BTDC
Intake valve closes at 85° ABDC vs. Ford spec of 54°ABDC
Exhaust valve opens at 89° BBDC vs. Ford spec of 58° BBDC
Exhaust valve closes at 41° ATDC vs. Ford spec of 8° ATDC

All opening and closing measurements were taken at .020" to compensate for valve lash, dial indicator inside of pushrod cup.

The intake lobe center angle came out to 112°.

Intake valve lift measured .278" (.298" - .020") vs. Ford spec of .264"

Exhaust lift measured .281" (.301" - .020") vs. Ford spec of .262"

Well, if all of you're measurements are correct, your cam has Intake specs of .428" lift at 294 degrees of duration, and the exhaust is .437" lift at 310 degrees of duration. I also assume the .278" and .281 lift measurements were cam lobe lift and not actual valve lift.
To me, this more than explains the low vacuum. Tons of duration and overlap. The lift isn't that radical, but the duration and centerline are for a pretty much all out racing cam for a Y-Block.

[Fordors]

Your specs show the Ford cam has a duration of 246* and the cam in your engine has 294*In. and 310*Ex. duration. Valve events of 29*IO+85*IC+180*= 294*. Next duration divided by two = 147* and subtracting 29* from that gives an intake centerline of 118*, not the 112* you saw. I think the .020 checking clearance you are using is too low a value and you are seeing errors in the timing events, and also, the use of the push rod cup can skew the readings. I think it would be better if you can take a direct reading from the top of the tappet. Initial lifter rise (your .020) is very slight per degree and for that fact it would be better to check valve events at .050. Most performance cam manufacturers will use .050 for the greater accuracy and the lower "effective duration" it will show.
Another thing I see is the dual pattern in your cam, 294* intake and 310* exhaust. True, specs given by Ford show variance in the timing between intake and exhaust but the duration is the same @ 294*, so the factory cam is set 2* advanced with a new chain and gears. You could have a dual pattern cam, I am not ruling that out, it may very well be.
I'm not saying your chain is good or bad, just that I would go back and check the cam at .050 and see what you get. At that point your intake centerline might coincide with the numbers. An IO event at 29*BTDC for a cam with 294* duration will have a c/l of 118*; if the c/l was at 112* for the same cam grind the IO event would have to be 35*BTDC. There is an error in your readings, but regardless, your low compression numbers may be due to the greater duration of a performance cam combined with stock pistons. Ole Don and Y-Blockhead both mentioned lower vacuum readings with aftermarket cams and I think that is also why you are seeing low vacuum.
Check cam specs at .050 before you do anything else and that may give some insight here. Possibly with those readings someone will have info on an aftermarket cam with like numbers.

[countrysquire]

Thanks, I'll check it at .050" and see what that shows.

[Oldmics]

Ford never used .050 for cam specifications in those early years.

To try and duplicate the factory specs your .020 measurements are probably pretty close

Unfortunatly I don't know where they checked for the 1955 cams.

I do have all the 56 and 57 cam check points (but that's no help)

I will say that based strictly on your lift measurements - its not a stock Y Block Ford camshaft from any era.

It is worth it to recheck at .050. Perhaps by posting up those measurements and IF its an Isky cam the pedigree can be disclosed.

Oldmics

[countrysquire]

Per the 1955 Ford shop manual:

Intake opens tappet lift @ degrees BTC - 12°@0.016
Intake closes tappet lift @ degrees ABC - 54°@0.019

Recommended valve lash is 0.018" hot.

I'm a little under the weather, so I didn't get a chance to check it at .050" yet, but will post the data once I do it and maybe we can figure out what's in there. I'm thinking that it's a case of mixing a big cam with stock compression ratio.

[Ole Don]

If you remove the cam, you can mail it to Comp Cams in TN. and for a very small fee, they put it on the cam doctor and get accurate measurements and make up a new cam card. Your measurements seem to be very good. Some companies give measurements at .050, and some at .020. You are in the ball park. The numbers you came up with is a wild - wild cam for so few cubic inches. With the correct valve springs, it should run to 7500 RPM's and make its best power between 4800 and 7000. The numbers are similar to the Iskenderian 505T I ran for two years. It didnt want to pull the car below about 2200 to 2500, but it 3500 it felt like it had a turbo. That was the engine I shifted at 7000. 287 HP in street trim on the chassis dyno on 91 octane with corn in it.

[jim galli]

You know that '56 - '57 rocker arms have a different lift ratio. Who knows what's in there. iirc those were the only 2 years with the better ratio, (also bigger ports,) as the 352 was the hot rod in '58 and the 292's were de-tuned to '55 numbers or less. Some of the Merc Y blocks kept the better heads and rockers for a couple more years? Maybe? It's all in a 1970's Hot Rod magazine article that I've kept somewhere in the rafters all these years.

Just googled it. September 1968 issue of Hot Rod mag. John Thawley wrote an article called "one more Y block" It has all the ECZ numbers and years of the stuff that flowed the best. Most of it 1956,57 If you can find that issue, it's excellent information. If not, let me know and I'll look for mine and maybe scan the stuff. Should be public by now.

[countrysquire]

Thanks Jim. Who knows what parts are on it? Once I have it out, I'll have a look at the casting numbers and at least figure out what the big pieces are.

I found an old link to the article that you mentioned:
http://www.oocities.org/yblockhead/OneMoreY_block.html

[jim galli]

Originally Posted by countrysquire

Thanks Jim. Who knows what parts are on it? Once I have it out, I'll have a look at the casting numbers and at least figure out what the big pieces are.

I found an old link to the article that you mentioned:
http://www.oocities.org/yblockhead/OneMoreY_block.html

That's the text, but the original article had a bunch of good sidebars with numbers and casting codes and duration of production. Dating myself. In 1968 I was only 16. Honest.

[countrysquire]

OK, leak tester built and it appears to work, based on a lot of correlation with the compression test. All the cylinders but two had between 25 & 35% leakdown. One cylinder only had 6%(!), and one had 75%. That one might have a problem. I went back and checked it again and got the same reading. Moving the crank back and forth made no difference, nor did tapping the valves. I followed that with a couple squirts of oil and retested. The pressure came out about 5 psi, but you could hear the air blowing through the oil. I guess this tells me that I better go ahead and open it up while it's out of the car.

[wellcraft17]

Well it looks as tho you have narrowed it down to camshaft and probably rings and I am assuming you will rering it and get a new stock cam providing the cyl. bores and crankshaft are good to go. You indicated the heads had recently had a valve job and I would put them back on but I would also check the valves seats for leakage prior to. Don't know if anyone still does this but we use to pour a little gas down the ports of the heads and look up in the cumbustion chambers and see if there was any seeping of gas around the head of the valve and seat after a valve job. Easy and quick way to check.

[countrysquire]

Yeah, I plan on doing a close inspection on everything while it's apart. Ordered a reground cam for Oregon Camshaft with a reground set of lifters. The cam is a stock '57 312 grind. Hopefully I will have the engine on the stand by this weekend.

[countrysquire]

OK, the engine is out and everything but the rotating assembly has been taken apart. Here's my initial observations while tearing it down.

• Relatively clean inside, piston tops have a bit of carbon, more than I would have expected.
• Flat top .060" over pistons, no ridge at the top of the cylinders, just a layer of carbon.
• The cylinder walls have a nice glaze, no crosshatching is visible.
• The cam is out, and it's labeled CRANE F-294-2. A search of Crane's website and a Google search don't come up with anything. I did find some stuff about an F-294 cam for an FE, but no telling if it has the same profile.
• Once I get the garage back in order, I will pull the bottom end apart, starting with #4 (the one with 75% leakdown). I'm guessing the ring lands are full of carbon, but we'll see.

[countrysquire]

#4 piston is out, but the rings weren't stuck like I was suspecting. However, the compression ring gap overlapped about 50%, so that should explain the leakdown for that cylinder.

I did a quick check on the bore and came up with 3.860", which can't be right. I don't have a bore gauge, so I have to do it with dividers and caliper, but that should be close enough for a rough measurement. I triple check, even changing calipers, but get the same reading. How could it be .110" over and be running .060 pistons? Could this be a 312? So I check and see the stock bore for a 312 is 3.800". Looking at McMaster's & Mummert's sites confirms that it's a 312. Casting number is ECZ-6015-C and it has ECZ main caps. The heads are the ECZ-G.

[40cpe]

It looks like you lucked up.

[countrysquire]

Yeah, normally I do something that rhymes with that!

[Tinker]

Pictures or it never hapened, ha ha.

Sounds like you have it pin pointed. Nice work!

[countrysquire]

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Now I'm curious to see how they lined up the other rings...

[sprink88]

THATS how the rings looked??? Wow

[40 Deluxe]

Be sure to check ring gap with the rings in the cylinders. Someone may have used 292 rings so the gaps are huge. Normally it does not matter where the ring gaps are because the gap area is so small and the rings constantly rotate in their grooves anyway. So the gaps will all line up and then move on, not lining up. Doesn't affect how the engine runs at all. You need to be concerned more with how well the rings are sealing against the cylinder walls as well as the ring lands (check for side wear on the rings).

[darrell]

with the ecz caps you do have a 312 but its common to bore a 292 to that size.the wristpin is in the same location so no problem.whoever did your engine was no pro.

[LOWRIDER]

X2 what 40 Deluxe said. Urban legend that it won't run correctly w/ the ring gaps lined up.

[countrysquire]

Measured gap on one of the compression rings on the #4 cylinder and it's .025", which is in Ford's spec range of .010 - .027", so they are the right rings.

[TedEaton]

Originally Posted by countrysquire

Now I'm curious to see how they lined up the other rings...

It's not unusual for the rings on a piston to be aligned once the engine has run for awhile. The rings do rotate normally and once the two compression rings align, they'll have a tendency to stay that way as it's the path of least resistance.