Question on cam gear marks

[Russ/40]

I have a V8 engine that just will not run correctly. I have rebuilt a few flatheads and never had a problem like this. Engine runs like the cam is way out of time. It does not sound like the typical flathead when cranking. No speed parts involved. 41 block with 8BA rotating assembly 3 3/16 bore.

When the cam and crank gear markings are matched, is number one supposed to be at TDC? Anyone run into mis-marked crank and or cam gears?

Engine, when cranking turns normal, then slows, then speeds up, then slows etc. like it is fighting an out of sync valve timeing. Runs with loud pops in exhaust with any throttle. Will idle well at low RPMs. Valve lash is 12 and 12.

Im tearing it back down. Comments on the valve timeing?

[tubman]

I believe that "GordonC" had this same exact problem. It took him a while to chase it down. See this thread : https://www.fordbarn.com/forum/showt...highlight=gear

[cadillac512]

Russ, one way to be sure the cam timing is correct: With the head off,when any piston is at tdc on the overlap stroke (exhaust valve closing while intake is opening) both valves for that cyl. should be open almost exactly the same amount.
Rotating the engine a bit either way will cause one valve to completely close...rotating the opposite way will cause the other valve to completely close.

This will be correct valve timing no matter what the marks say.


Terry

[Russ/40]

Thought I would add a few facts. I'm running a helmet '40 distributor, with the '40 pulley, so I have no pointer and cover to use as reference. I will use the ref photo and the zip tie for idc today.

[JSeery]

Russ, this is why it is a good idea to degree every cam when you install it. About the only way to know what you have and how it is installed.

[Russ/40]

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The cam is an Isky 77B that i have run before, so its not the cam. I did the zip tie today for tdc and changed the front cover and pully to the 8BA setup, and my tdc 's both matched perfectly. Not a cam issue after all.

Now the confession, I did the lash the Ford way originally, grinding stems. Unfortunately my grinding setup was difficult to implement. My goal was to set everything to .012" lash. Today I reviewed all the lash measurements and well, I'm humbled. Did not do a very decent job. I'll try posting a photo I took of all the lash specs as well as installed spring height numbers. The question is, is the data so bad as to make the engine run like sxxt.

I hope you can read this if not, I'll work on it. The 2 digit #s are the lash and the 4digit #s are the installed spring height.

My concerns, the installed height OK with stock springs and lastly are my lash numbers responsible for a VERY bad running motor. Please help this nit\wit!

[cadillac512]

Russ, the lash isn't great but it isn't the cause of the running problem. It may be a bit noisy on a few valves,but just a bit...can't make it run badly.
As for the spring heights,well, they are quite bad with .100" difference low to high. I need to look up the specs for stock height (can't remember darn it!) but they for sure should be closer than they are,and closer to the higher number than the lower. No spring pressure will sure run badly,but if it has any at all it should crank evenly.


Just looked it up; Spring ht valve closed 2.130" You do have the "long" springs, correct? Not the ones with "rotators" from '52-'53? And the proper retainers to suit?


Are you absolutely certain the plug wires are in the correct firing order? (probably so since that doesn't explain the weird cranking.)
I'd check compression with the throttle blocked wide open and all the plugs out. May be a couple valves not sealing.



Terry

[Russ/40]

Thank you for responding Terry.
100% sure the fireing order is set correctly. I am using the older stock spring components, not the rotators Also pertinent, I am running Chevy valves with the double set of grooves, and the locks are in position for the springs being the shortest. My measurements show the install height to be 5/16", shorter than what a stock flathead valve would bring. A compression check shows numbers 87lbs to 100lbs.
Any and all comments welcome. The engine now sits on a stand with heads and pan in place. Trying to decide if I should remove the heads and redo the valve train. I'm sure the installed height issue is do to some seats are pretty low.

[JSeery]

As I am sure you are aware, these are not good compression numbers for a new rebuild. Might do a leak down test and see if that tells you anything. Cam timing would lead to poor compression numbers, but so would ring issues. Or valve seat issues.

[Ronnie]

This is orientation for the grooves on a Chevy valve. Keeper goes in top groove as per picture.


R

[JSeery]

Also, are not spacers required with Chevy valves? I have always had to use a spacer.

[Ronnie]

I always use valve locks that are compensated .070" to shorten the installed height made by a couple of places available real easy.
https://www.alexsparts.com/locks-kee...75-down-locks/
comp cams also



R

[cadillac512]

If I subtract your lowest spring height of 1.854" from an in-spec height of 2.130" I get .276" difference, and that's shorter. Is the spring coil binding when the valve is fully open? If so, it'll destroy the cam...maybe pull the intake and have a look. If there is coil bind,the cam and lifters will need inspecting as well.


Terry ( I hope this isn't the case!)

[Russ/40]

No Terry, there is no coil bind. There would be I bet, if I was using rotators.

[Russ/40]

Originally Posted by Ronnie

I always use valve locks that are compensated .070" to shorten the installed height made by a couple of places available real easy.
https://www.alexsparts.com/locks-kee...75-down-locks/
comp cams also

R

Those are $9 each - ouch!

[bbrocksr]

Originally Posted by Russ/40

Those are $9 each - ouch!

$9.00 for a 1/2 set, not each.

$9.00 x 32 = $288.00, pretty spendy for a set of keepers.
Bill

[Ronnie]

Some past info here on springs.
https://www.fordbarn.com/forum/showthread.php?t=216777


R

[mfirth]

Russ i had an 8ba done 3 yrs ago and the new cam gear was mismarked. Dot was off by 2 teeth. Also had a new oil pump {both parts were Mellings}..... junk. Lower oil pressure than before rebuild. Others have had cam gear problems too...............

[Ronnie]

Did you talk to Melling about the items? they are a fine company and would help you out.



R

[Russ/40]

Originally Posted by Ronnie

Did you talk to Melling about the items? they are a fine company and would help you out.

R

I confirmed the cam is ok because I have run it before in another motor.

Compared to another, the cam gear is properly marked.

[Ronnie]

Good


R

[Ggmac]

Just a guess , a loose valve seat ? Valve guide broken ? Massive vacuum leak ?
You’ll figure it out . Probably around 2 am while sleeping . Some of my most hardest problems are solved that way .

[Ggmac]

Originally Posted by Russ/40

I confirmed the cam is ok because I have run it before in another motor.

Compared to another, the cam gear is properly marked.

Ive been thinking , what kind of cranking noise does it make with no spark ( removing coil wire ) is it the same strange cranking ? If not check for cap problems , carbon tracking offset internal posts , etc . If it does still crank strange, remove one plug at a time and with no spark , crank . Replace that plug and crank until you hopefully find one that stops the strange cranking . If one plug improves it but doesn’t eliminate it , mark that cyl and see if any others also improve it but doesn’t completely eliminate it . Then remove all the plugs that improved the cranking . Hopefully theres only one maybe 2 . Then its at least narrowed down .
Good luck , i hope this testing process makes sense ,
Gary

[Russ/40]

Gary, with all plugs removed it cranks like any other flat v8. When running, I have removed ignition from each plug and checked how it reacted and with throttle. All seemed to respond in a similar manner. Thanks for thinking about my problem. I'm putting it aside for a few days to put my thoughts together.

[Brian]

Russ, I've been following this thread. A bit hard to diagnose over the computer. However, the first thought I had, I haven't seen it mentioned, but a very useful diagnostic tool is a vacuum gauge. Such a device can be handy for pinpointing late valve timing, sticking valves, ign timing, etc....Can you possibly run it with a vac gauge hooked up?
My other thought; a blown out heat riser in the inlet manifold.

Good luck, Brian

[Russ/40]

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Hi Brian, the engine is partially torn down for visual inspection. I'm considering pulling the heads so i can check the rings for broken. When putting some of the pistons in, i had a problem with the multi-piece oil rings catching the upper detent left from pulling the original sleeves. I ended up using a thin wall steel sleeve as my ring compressor after putting a knife edge on the sleeve to get past that ridge at the cylinder top. This has been the "Engine from hell" since the very beginning. It was originally built by a shop, and I found a lot wrong with it, including a cylinder crack they missed. I put a low mileage 8ba crank in this '41 block at 3 3/16ths with std bearings with the intent of makeing a decent backup motor.

I really am interested in your blown heat riser suggestion. I will check that!

[Automotive Stud]

Originally Posted by Russ/40

I have a V8 engine that just will not run correctly. I have rebuilt a few flatheads and never had a problem like this. Engine runs like the cam is way out of time. It does not sound like the typical flathead when cranking. No speed parts involved. 41 block with 8BA rotating assembly 3 3/16 bore.

When the cam and crank gear markings are matched, is number one supposed to be at TDC? Anyone run into mis-marked crank and or cam gears?

Engine, when cranking turns normal, then slows, then speeds up, then slows etc. like it is fighting an out of sync valve timeing. Runs with loud pops in exhaust with any throttle. Will idle well at low RPMs. Valve lash is 12 and 12.

Im tearing it back down. Comments on the valve timeing?

I think you may have made an obvious mistake that nobody has caught yet. The timing marks on the cam and crank gears line up when the piston is at the top of the cylinder and the cam is at the beginning of the cycle, before the intake valve opens. The spark plug firing at TDC occurs at the end of the second stroke of the piston, so TDC for firing purposes occurs when the crank mark is straight up and the cam mark is straight up also. Look at this illustration and note that the colored wheel represents the camshaft. I don't think your cam is in wrong, I think your firing order is way out.

Edit: I was hoping this gif would be animated. You can see it move here: https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAD

[Ronnie]

This a cut and paste from Gofast 2017 Works well one turn of the cam and done.


R







Easiest method we've found is follow the firing order, set both valves on that cylinder that would be firing!

Two complete turns of the engine, you're done. Doesn't get any easier!

Thanks, Gary in N.Y.

P.S. This method will allow you to double-check the valves already set by spot-checking all the previously set valves. If any change is felt on any already adjusted simply re-set it at that point! __________________

[v8nut]

I have posted a pic of the cam and cam gear marks on my 1935 21 stud.. I took this picture after a very bad experience with this engine. As you can see the mark on the cam is very small and hard to see if you don't know what you are looking for. Earlier my engine rebuilder had an apprentice assemble the engine. He didn't know what he was doing and assembled (pressed on) the cam to cam gear miles off the the correct spot. Of course the engine did not run and it didn't take too long to figure what the problem was. As you probably can imagine it was a lot of work to fix it. I was not pleased. At some point later the design of the cam to cam gear assembly was changed to preclude the ability to make this mistake. Jim in San Jose

[Bored&Stroked]

Checking the cam timing with a degree wheel is never a bad idea - I always do this. BUT, unless the cam is manufactured incorrectly (or you want to alter the timing), and both gears are correctly manufactured, then all you do is put the crank in first, with the crank gear timing mark straight up, then put the cam in so the mark on it's gear aligns to the crank gear. Assuming you have a bolt-on cam gear, there is really nothing to think about as far as where the valves are located . . . just align the dang marks. As the cam gear is indexed to the cam bolts, it can't be installed incorrectly - so if the cam/crank gear marks are aligned, then you're good to go.

Validation: You can then install both valves on #1 cylinder, figure out where TDC is (you'll need a way to create a timing pointer and mark the crank pulley), then you can use a degree wheel and validate the cam timing. It is NOT uncommon to find that some of the aftermarket performance cams grinders - do not deliver cams that correctly match their timing tags. Even worse, in some cases you can't even advance/retard the cam to get them to a correct timing - as the lobes themselves are "off".

[Automotive Stud]

Originally Posted by Bored&Stroked

Assuming you have a bolt-on cam gear, there is really nothing to think about as far as where the valves are located . . . just align the dang marks. As the cam gear is indexed to the cam bolts, it can't be installed incorrectly - so if the cam/crank gear marks are aligned, then you're good to go.

Right, but if he also set the distributor at #1 TDC at this point, that's wrong. Both timing marks should be straight up, not facing each other, at the firing point.

[Bored&Stroked]

Originally Posted by Automotive Stud

Right, but if he also set the distributor at #1 TDC at this point, that's wrong. Both timing marks should be straight up, not facing each other, at the firing point.

Not to be a pain, but have you worked on one of these early flathead engines? The end of the cam has a t-slot in it, that is offset, so the distributor can only go on in one direction, it cannot be 180 degrees out of time, unless you incorrectly force it into the slot, which will break the casting when you turn it over.

Ford made this stuff really simple -- if you aligned the timing marks on the gears, then you should be good to go - as the distributor can be taken on/off the vehicle and the timing does not change - due to the indexed/offset t-slot. Hope this helps!

B&S

[Ronnie]

Automotive Stud When you put the cam in a flathead for the first time where are the timing marks at. Lined up cam mark at 6 o clock and crank mark at 12 o'clock or cam and crank both at 12 o'clock. Tell us.


R

[Automotive Stud]

Originally Posted by Bored&Stroked

Not to be a pain, but have you worked on one of these early flathead engines? The end of the cam has a t-slot in it, that is offset, so the distributor can only go on in one direction, it cannot be 180 degrees out of time, unless you incorrectly force it into the slot, which will break the casting when you turn it over.

Ford made this stuff really simple -- if you aligned the timing marks on the gears, then you should be good to go - as the distributor can be taken on/off the vehicle and the timing does not change - due to the indexed/offset t-slot. Hope this helps!

B&S

I read too quickly, I saw 8ba rotating assembly in his initial post and assumed 8ba type distributor also.

Originally Posted by Ronnie

Automotive Stud When you put the cam in a flathead for the first time where are the timing marks at. Lined up cam mark at 6 o clock and crank mark at 12 o'clock or cam and crank both at 12 o'clock. Tell us.


R

Yes that is correct, same as anything else.

[Ronnie]

Automotive Stud You are thinking the flathead tdc when cam is first in that it the same as what happens with a small block chevy. They are not the same. When marks are set up with a small bloc that is at tdc #1 cyl is at tdc exhaust and tdc #6 is at tdc compression. In a flathead when marks are at 6 cam and 12 crank the engine is at tdc compression # 1 no need to do anything.. In a small block some turn as you say to put it at #1 tdc compression that is up to the builder. That isn't really required if the dizzy is installed with the rotor pointing at #6 as the engine is already at compression on 6.You can wire starting with 6 and carry on from there or turn engine till rotor lines up with #1 and start plug wires from there.


R