Finally some Cam Degree Numbers - Now what?

[Russ/40]

I'm back, and have no idea what I am supposed to make out of the numbers. Here they are. If you recall I have been reluctant to pull the heads, and it was suggested I degree the exhaust valve on number one.

Reconfirmed TDC and very repeatable.
The info I found on the 77B: Int and Exh durations 260* or 220* at .050"
Lobe separation 111*, lift .325* Lash .014".

I got: .050" open at 148*
Exhaust starts to open @ 120.5*
Exhaust starts to close @ 348.5*
Exhaust is closed at 9* ATDC
Exhaust Lash is .014"

Is this enough to get a feel for the cam location? What else need I do. Exhaust centerline?

[flatjack9]

I know I have degreed a 77B. When I get down to the shop I'll see what kind of numbers I have

[JSeery]

I assume you have the cam timing specs? It is not totally clear from what you posted what lift you are checking at. The spec is for .020 valve lift with zero valve/lifter clearance. There is a second set of specs for .050. Values are in BBDC and ATDC. Sorry, looks like they are measuring at .014 valve/lifter clearance (I would call and check on that one).

[flatjack9]

I think they measure from the base circle.

[Brian]

I think Jack is right, ie, they measure from base circle...
however, going by your numbers you have;
ex opens 59.58 BBDC
ex closes 9* ATDC
This gives a duration of 248.5* as opposed to their stated 260*
Looks like your opening is close, however the closing is too early.
The closing events are more important than the opening....so, if you retard the cam by the one tooth as I suggested earlier, the new figures will be;
open 51.5* BBDC
closes 17* ATDC
duration obviously remains the same @ 248.5*
Furthermore, by doing this the distributor timing will be knocked back 16* and will be near where it should be.
My opinion....
I would have checked both inlet and exhaust timing events during the initial assembly

[JSeery]

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Problem is if the valve lash is in there it will change the opening and closing events. I have always used zero valve lash, but the cam specs are a bit confusing on that.

[Bored&Stroked]

You should do it with zero lash - and use the .050 numbers (they tend to be more accurate). We have no idea as to how the opening ramps influence the timing - only way to figure it out is with the heads off and checking the timing of both valves - and I'd do both at .020 as well as .050 (to compare). Given your lash of .014, you can look at the .020 timing to get a rough idea as to how close you are.

Just from what you've posted, seems the cam does not truly have the duration that it was advertised with. Comparing .020 to .014 lift, the valve should open SOONER than the timing tag and close LATER - it closes quite early.

[JSeery]

Think I would stick a shim in between the lifter and the valve stem to get the valve lash out of the process.

[Bored&Stroked]

Originally Posted by JSeery

Think I would stick a shim in between the lifter and the valve stem to get the valve lash out of the process.

Or, if you have "adjustables", just back out the adjuster until you feel it tight against the valve (when the lifter is on the heel of the cam). Even if you go a bit too far, you've taken up the slack.

[Bored&Stroked]

Originally Posted by JSeery

Problem is if the valve lash is in there it will change the opening and closing events. I have always used zero valve lash, but the cam specs are a bit confusing on that.

The cam card clearly denotes what it SHOULD be - and that the checking clearance is 0. What he is probably going to find is that the cam does not match the card - which I've seen MANY times. If the grind itself is off, there is nothing he can do to "fix" it . . . he can advance/retard it, but that is it.

[JSeery]

Originally Posted by Bored&Stroked

The cam card clearly denotes what it SHOULD be - and that the checking clearance is 0.

That's the way I would read it as well (and the way I have always checked a cam). But I can see how it is somewhat confusing to then put a valve clearance in with the event specs.

[bbrocksr]

Originally Posted by Russ/40

I'm back, and have no idea what I am supposed to make out of the numbers. Here they are. If you recall I have been reluctant to pull the heads, and it was suggested I degree the exhaust valve on number one.

Reconfirmed TDC and very repeatable.
The info I found on the 77B: Int and Exh durations 260* or 220* at .050"
Lobe separation 111*, lift .325* Lash .014".

I got: .050" open at 148*
Exhaust starts to open @ 120.5*
Exhaust starts to close @ 348.5*
Exhaust is closed at 9* ATDC
Exhaust Lash is .014"

Is this enough to get a feel for the cam location? What else need I do. Exhaust centerline?

Russ, A 77B intake opens 19* btdc exhaust closes 19* atdc for a total of 38* overlap. So as Ron says if you split the overlap you're at tdc. Probably the best way to check valve opening and closing is to pull the intake manifold and put an indicator on the cam followers. Then you don't have to worry about valve lash. If when you split the overlap the piston is at tdc the cam is timed correctly.
Bill

[Bored&Stroked]

Bill has it correct - as this particular cam has the same exhaust lobe profile as the intake. There are other cams where the profiles are different and the split overlap method doesn't work - you actually have to know where a particular lobe is in relation to TDC . . . and hopefully the profile matches the CAM card.

[Russ/40]

Is the opinion the duration is 248 vs 260 due to the .014" lash? It seems logical to me. In any case, is the deviation from 260 durationan issue responsible for the extreme static advance I see at idle (.025*)?

I'm trying hard to follow all the observations and to make sense of it all.

Bill, I find your comment of using an indicator to track the followers from inside the valley interesting, but not practical, as I can't imagine accomplishing that with the heads on. That would be the parallel of how it would be done on an overhead valve engine. The lash compensation with a shim or lifter adjustment sounds reasonable to me.

I hope we are focusing on the way to use this cam and at the same time correct the overriding concern which is making the engine run reasonably well. Remember the cam ran well before in a different engine with different crank and cam gears.

You guys are great, sharing your knowledge with me, and I am learning a lot about cam timing. I think I'm close to the next thing that I must do to solve the problem, and that I think is to retard the cam. Should I recheck everything with zero lash at this point or would It be reasonable to back the cam. Off one tooth now?

[flatjack9]

I dug out an old profile I did of a 77B. Looking at 014 lift figures, I have the valve opening at 86 BBDC and closing at 25 ATDC. These numbers don't correlate will with advertised numbers and I measured .360 lift, so not real confident in this cam. Someone may have put a regrind on it.

[GOSFAST]

The only number you really need to properly degree the cam is the "ICL", this number tells the whole story! You don't check this with any lash included, it's normally done with the lifter riding on the #1 intake lobe and the dial indicator on the lifter!

Don't confuse this with the "LSA", two totally different animals!

I would not pay too much attention to the "events", it's difficult at best to dial in any cam with the "4" event numbers!

Thanks, Gary

P.S. Been using the "ICL" method for more than 55 years now in all our builds!

[bbrocksr]

Originally Posted by Russ/40

Is the opinion the duration is 248 vs 260 due to the .014" lash? It seems logical to me. In any case, is the deviation from 260 durationan issue responsible for the extreme static advance I see at idle (.025*)?

I'm trying hard to follow all the observations and to make sense of it all.

Bill, I find your comment of using an indicator to track the followers from inside the valley interesting, but not practical, as I can't imagine accomplishing that with the heads on. That would be the parallel of how it would be done on an overhead valve engine. The lash compensation with a shim or lifter adjustment sounds reasonable to me.

I hope we are focusing on the way to use this cam and at the same time correct the overriding concern which is making the engine run reasonably well. Remember the cam ran well before in a different engine with different crank and cam gears.

You guys are great, sharing your knowledge with me, and I am learning a lot about cam timing. I think I'm close to the next thing that I must do to solve the problem, and that I think is to retard the cam. Should I recheck everything with zero lash at this point or would It be reasonable to back the cam. Off one tooth now?

You should find out where you're at before you start retarding the cam.
Better verify the cam is timed wrong before you change it.
Bill

[bbrocksr]

Originally Posted by Russ/40

Is the opinion the duration is 248 vs 260 due to the .014" lash? It seems logical to me. In any case, is the deviation from 260 durationan issue responsible for the extreme static advance I see at idle (.025*)?

I'm trying hard to follow all the observations and to make sense of it all.

Bill, I find your comment of using an indicator to track the followers from inside the valley interesting, but not practical, as I can't imagine accomplishing that with the heads on. That would be the parallel of how it would be done on an overhead valve engine. The lash compensation with a shim or lifter adjustment sounds reasonable to me. , It's a lot more correct the overriding concern which is making the engine run reasonably well. Remember the cam ran well before in a different engine with different crank and cam gears.

You guys are great, sharing your knowledge with me, and I am learning a lot about cam timing. I think I'm close to the next thing that I must do to solve the problem, and that I think is to retard the cam. Should I recheck everything with zero lash at this point or would It be reasonable to back the cam. Off one tooth now?

Russ ' It's a lot more practical than retarding a cam when you don't know where it's at! You don't know for sure that it is a cam timing problem.
You should find out where you're at before you start retarding the cam.
Better verify the cam is timed wrong before you change it.
Bill

[flatjack9]

Originally Posted by GOSFAST

The only number you really need to properly degree the cam is the "ICL", this number tells the whole story! You don't check this with any lash included, it's normally done with the lifter riding on the #1 intake lobe and the dial indicator on the lifter!

Don't confuse this with the "LSA", two totally different animals!

I would not pay too much attention to the "events", it's difficult at best to dial in any cam with the "4" event numbers!

Thanks, Gary

P.S. Been using the "ICL" method for more than 55 years now in all our builds!

With the 77B, the exhaust c/l will be the same as the intake c/l. Isky says 111* for both. Also Isky specs their cam events at .020 lift. By using Russ/40 numbers, I come up with 120* c/l which would indicate the cam timing is off by one tooth,

[flatrod]

How is the compression? Retarding it will be losing compression, advancing it will add compression. It won't be much, maybe 20 pounds but its noticeable. Advancing it more than 4 degrees will start to lose compression again. Installing at the highest compression will be the best running, but that's a lot of dicking around to find it. I would go with a intake center line spec if you have it.

[bbrocksr]

Originally Posted by Russ/40

I'm back, and have no idea what I am supposed to make out of the numbers. Here they are. If you recall I have been reluctant to pull the heads, and it was suggested I degree the exhaust valve on number one.

Reconfirmed TDC and very repeatable.
The info I found on the 77B: Int and Exh durations 260* or 220* at .050"
Lobe separation 111*, lift .325* Lash .014".

I got: .050" open at 148*
Exhaust starts to open @ 120.5*
Exhaust starts to close @ 348.5*
Exhaust is closed at 9* ATDC
Exhaust Lash is .014"

Is this enough to get a feel for the cam location? What else need I do. Exhaust centerline?

Russ, In your numbers you say the exhaust closes at 9* ATDC, the 77B is supposed to close at 19* ATDC. That's 10* early, If you closed up the lash what would it close at?
Bill

[Russ/40]

Originally Posted by flatrod

How is the compression? Retarding it will be losing compression, advancing it will add compression. It won't be much, maybe 20 pounds but its noticeable. Advancing it more than 4 degrees will start to lose compression again. Installing at the highest compression will be the best running, but that's a lot of dicking around to find it. I would go with a intake center line spec if you have it.

flatrod, I repeat from an earlier post, the cam ran fine in my car a number of years ago. The cam now is in another engine. The engine will not time correctly with a setup stock helmet type Ford distributor. It static times at 25 degrees advance. At rpm it will advance to 35 degrees. The centerline is supposed to be 111 degrees both intake and exhaust. As flatjack9 states, the centerline or lobe center is at 120 degrees, so, if the 77b is the same lobe center int and exh, the cam is ok, but its not timed correctly, which corresponds with my original complaint regarding where the static timing is

Compression is low, about 85lbs. Probably due to extreme advance.

bbrocksr, - since I am using a dial indicator on the valve head, in my way of thinking the lash is of no concern, as I am taking it out of the equation by measuring only valve movement.

[frnkeore]

I assume that your working with a bolt on cam gear and not a press on?

If so, this is how you can time the cam. turn the engine, until the valve are both open, the same amount. You can do that with 2 indicators or, you can use a straight edge, across them, if the margins are the same (indicators preferred).

Then, with the #1 piston at TDC, slide the cam gear into place, on the cam. If the holes line up, the cam will be set, at or very close to "split overlap" or the other term, is "straight up".

If it doesn't line up, you'll have to off set it, to get the correct timing.

Nothing new, I learned this from Chet Herbert (of roller cam fame), when I was very young.

[Ol' Ron]

I've never given mush thought to the 77B cam as it quite mild and doesn't offer much in performance. With todays prices I would think that spending 500$ bucks on a cam Assy, you might consider the application alittel better. The stock EB cam might work just as well, or a Max #1might give bette rpreformance. If you want a Rump- Rump cam just pull out the choke alittle bit and you have a free L-100
Gramps.

[Russ/40]

Originally Posted by Ol' Ron

I've never given mush thought to the 77B cam as it quite mild and doesn't offer much in performance. With todays prices I would think that spending 500$ bucks on a cam Assy, you might consider the application alittel better. The stock EB cam might work just as well, or a Max #1might give bette rpreformance. If you want a Rump- Rump cam just pull out the choke alittle bit and you have a free L-100
Gramps.

Thanks Ron. I'm trying to utilize a cam that's been sitting for a number of years. Not trying for any performance over stock, just trying to get another one running. I seem to have come upon a erroneously marked cam gear

[Ol' Ron]

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The 77B would be a nice cam for a street blower system.

[Russ/40]

Originally Posted by Ol' Ron

The 77B would be a nice cam for a street blower system.

I'd have to be a LOT smarter to even consider that!

[Ronnie]

Originally Posted by Russ/40

Thanks Ron. I'm trying to utilize a cam that's been sitting for a number of years. Not trying for any performance over stock, just trying to get another one running. I seem to have come upon a erroneously marked cam gear

Where did the gear come from and how long have you owned it.


R

[Russ/40]

Originally Posted by Ronnie

Where did the gear come from and how long have you owned it.


R

The gear came from a stash of apparently used V8 parts I bought over 10 years ago.

The cam came from a motor I ran in my '40 years ago.

[Ol' Ron]

SOUNDS LIKE A GOOD PLAN. nOTHING VENTURED, NOTHING GAINED. Good luck.
Gramps

[JSeery]

Easiest thing at this point, at least in my mind, would be to replace the timing gear or try moving it a notch over and recheck the valve timing.

[Ol' Ron]

Back in the day whenyou had to buy your way out of a problem, we slotted the cam holes and used ster washers under the hold doew locking plate, Cams never moved.. Skipping a tooth is 16 degs I think.
Gramps

[flatjack9]

8 degrees

[Bored&Stroked]

Depends "which" degrees you're all talking about. Crank versus cam . . .

[Ol' Ron]

??????????????????

[Bored&Stroked]

Originally Posted by Ol' Ron

??????????????????

While one cam-gear tooth is approximately 8 degrees of cam timing, the crank turns at twice the speed, so it is 16 on the crank.

360 / 44 = 8.18 (cam gear has 44 teeth)
360 / 22 = 16.36 (crank gear has 22 teeth)

So if you move the cam one tooth in either direction, you're changing the timing events on the cam by 16 crankshaft degrees (which is where all the timing numbers come from - a degree wheel on the crank).

I kind of doubt that he needs to move it that much - he probably needs a "tweener" - something in the middle. So, I'd try a new cam gear first (to see if it was somehow indexed wrong on the bolt holes). If that doesn't work, then you either custom drill a cam gear (on a mill with the correct tooling), or you come up with a method of increasing the bolt hole size and using some "offset" cam bolt-bushing sleeves (like we used to do before we had adjustable timing chains on SBCs).

Hope this makes sense . . .

B&S

[Ol' Ron]

And the ster washers worked just fine.

[JSeery]

Originally Posted by Bored&Stroked

I kind of doubt that he needs to move it that much - he probably needs a "tweener" - something in the middle.
B&S

From Ross's original post on this topic:

"Side distributor timing set for 1/2 increment advance, like every other flathead I've had which was correct. Net is again 25 degrees advance at idle. Vacuum brake is screwed all the way in, but will still advance to about 35 degrees with RPM."

This is off quite a bit, sounds close to one tooth of the cam gear to me, maybe two.

[flatjack9]

Not 2.

[Ronnie]

go here



https://www.fordbarn.com/forum/showt...66#post1935866


Read the first post he states he checked cam gear and it was ok. Now current post is backtracking. Info has changed since then!!!



R

[JSeery]

Originally Posted by Ronnie

go here

https://www.fordbarn.com/forum/showt...66#post1935866

Read the first post he states he checked cam gear and it was ok. Now current post is backtracking. Info has changed since then!!!
R

He checked that the mark on the cam gear lined up with the mark on the crank gear. The current question is if the cam gear is mismarked.

[Ronnie]

Originally Posted by JSeery

He checked that the mark on the cam gear lined up with the mark on the crank gear. The current question is if the cam gear is mismarked.

Cut and paste tells me he checked that


"After comparing the cam gear with another, matching bolt patterns and matching marks. I left the cam and crank gears in place. The cam itself has been run in another motor so I was convinced the cam itself is a good 77B."

[Bored&Stroked]

Just some numbers to ponder: His readings show the exhaust closing at 9 ATDC - with .014 lash. The cam card specifies 19 degrees ATDC - with zero lash. So you can assume that with zero lash, it will close LATER than 9 degrees . . . probably a couple more.

So, with some guesstimating, maybe 11 - 12 degrees afterwards. So, that means you need about 8 more crankshaft degrees (retarded) to get it to 19 . . . hence my thinking that he'll need a "tweener". From his original numbers, I doubt a whole tooth will get him where the cam card says it should be.

To backup a bit, we don't know WHAT mechanical problem is causing his issue - could be the crank gear, could be the cam gear, could be how the cam was ground, advance issue (timing) can also be related to the cam slot location . . . or a combination of all of these.

To me, one has to pull the heads, zero the lash, get a dial indicator, use a mag base and a good degree wheel - and start from there. Only then will he be able to truly figure out the accurate "as is" cam timing - then you go from there.

I'd do this before undertaking any sort of "fix". With that said, one can do the "catch me screw me" method of just trying stuff - but I've never found that to be terribly successful and also one never truly knows what the root cause was in the first place.

Best of luck!
B&S

[Ronnie]

Yup x 2 ^


R

[Russ/40]

I appreciate the lesson in cam checking, but as the process has unfolded, I don't understand why more attention wasn't paid to the fact this cam ran fine in an earlier installation. It simply came down to "what caused the static timing to be so advanced. It wasn't the cam, demonstrated by prior use, but the cam was off time. The cam gear was the only component with which I had no prior use experience.

I generated the numbers requested for the cam which were actually quite relevant and helpfull, as both Int and Exh had the same lobe center, so a decent set of exhaust numbers said a lot. I am happy I did not succumb to pulling the heads again as it made no sense to do so with the info that was obtainable from the exhaust valve, and the cam history.

I did learn a lot from you guys, and I thank you for your time analyzing what info I was able to provide. Special thanks to "flatjack9" for coming up with the solution to the problem. His recommendation to retard the cam one tooth brought the timing right down to where it is supposed to be. The timing gear was miss-marked. I pulled the cam gear, advanced the crank one tooth, put the gear back on and walla, timing perfect. It runs great too.

I must add. I have become a believer in the wisdom of checking a cam early in a build.

[Zeke3]

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I enjoyed following along on your ordeal, glad to hear you were able to resolve the cam timing issue. I better buy a degree wheel.

[Brian]

Glad to hear you finally took my advice....you could've had this sorted weeks ago!

[JSeery]

Originally Posted by Russ/40

I appreciate the lesson in cam checking, but as the process has unfolded, I don't understand why more attention wasn't paid to the fact this cam ran fine in an earlier installation. It simply came down to "what caused the static timing to be so advanced. It wasn't the cam, demonstrated by prior use, but the cam was off time. The cam gear was the only component with which I had no prior use experience.

I generated the numbers requested for the cam which were actually quite relevant and helpfull, as both Int and Exh had the same lobe center, so a decent set of exhaust numbers said a lot. I am happy I did not succumb to pulling the heads again as it made no sense to do so with the info that was obtainable from the exhaust valve, and the cam history.

I did learn a lot from you guys, and I thank you for your time analyzing what info I was able to provide. Special thanks to "flatjack9" for coming up with the solution to the problem. His recommendation to retard the cam one tooth brought the timing right down to where it is supposed to be. The timing gear was miss-marked. I pulled the cam gear, advanced the crank one tooth, put the gear back on and walla, timing perfect. It runs great too.

I must add. I have become a believer in the wisdom of checking a cam early in a build.

Way to go Russ!!!