Need help from the flathead gurus...? Valve clearance issue

[crazycasey]

Hey there,

I'm assembling a '49 Ford flathead V8 engine. It's my first flathead build; I bought the usual books, and I've felt fairly confident in the build so far.

I'm running an Isky 88 cam, reground from my stock core, stock hollow bodied lifters, and Chevy valves, and now I'm adjusting the valves. I set all the intakes at 0.011" and all the exhausts at 0.014". Except for one. The number 4 exhaust valve is at 0.014" when I assemble it in the block, but then I crank the engine over and check it again, and it's at 0.016", and again and I'm at 0.020", and so on and so forth. It'll grow all the way to about 0.030".

I'm kind of at my wits end. The cam looks good. The lifter appears to be in good shape, spinning it in a pair of calipers it appears to be perfectly square top to bottom. Valve, guide, spring, locks, and retainer are all new and look good. The only thing I didn't replace is the little crows foot that holds the guide in the block, but it appears to be seating properly and in good shape. What am I missing!?

Thanks for the help. I've gotta call it a night. Hope somebody can point me in the right direction.

[crazycasey]

I think I've got to set a dial indicator on top of the valve, and see if the head of the valve is moving as my clearance increases. It doesn't look like it's moving. I'd think I could see 0.015" with the naked eye.

[51 MERC-CT]

Assuming that you are taking the reading when the cam is in it's correct position. A 'sticky' valve guide could cause this. When it is at it's widest gap, tap down on the valve to see if the gap changes. If not then it's most likely a problem below the valve such as in the lifter or cam area.

[chap52]

I recently had an issue where the gap would lessen after turning the engine a couple of times and rechecking. Found that the lifter was not settling on the cam as it should. So I always make sure that I push down on a lifter to be sure it is seated before I adjust it.
I am sure you are adjusting the exhaust valve just as the intake valve closes, right?
Don't get discouraged. You'll get it.

[Walt Dupont--Me.]

I had a cam ground years ago, who ever ground it didn't cut the meat between the lobes and the lifters would ride up on that meat, had to sent the cam back. Also the cam will ride ahead with out the front cover on. I just take a piece metal and drill a 5/16 hole in it and bolt it to front so the cam will ride against the piece of metal. SO, make sure the lifters are rideing in the center of the cam lobes.

[Walt Dupont--Me.]

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I spend alot of time ajusting valves, good thing I don't punch a clock. I usually ajust them about .002 tight and hook them all up, spin the cam over a few times, now check clearance one at a time, usually have to grind .001 or .002 it takes a long time but they will be perfect, I hate to have one valve going tick tick tick. Walt

[crazycasey]

Originally Posted by 51 MERC-CT

Assuming that you are taking the reading when the cam is in it's correct position. A 'sticky' valve guide could cause this. When it is at it's widest gap, tap down on the valve to see if the gap changes. If not then it's most likely a problem below the valve such as in the lifter or cam area.

I think this has got to be what's happening, but what's the fix!? Shouldn't the spring hold the guide tight against the block? Anyway, I'll get out there in a little bit and check as you suggested, just not sure what to do from there.

Originally Posted by chap52

I recently had an issue where the gap would lessen after turning the engine a couple of times and rechecking. Found that the lifter was not settling on the cam as it should. So I always make sure that I push down on a lifter to be sure it is seated before I adjust it.
I am sure you are adjusting the exhaust valve just as the intake valve closes, right?
Don't get discouraged. You'll get it.

Thanks. Yes, I am using the EOIC method. And I am pushing down on the lifters.

Originally Posted by Walt Dupont--Me.

I had a cam ground years ago, who ever ground it didn't cut the meat between the lobes and the lifters would ride up on that meat, had to sent the cam back. Also the cam will ride ahead with out the front cover on. I just take a piece metal and drill a 5/16 hole in it and bolt it to front so the cam will ride against the piece of metal. SO, make sure the lifters are rideing in the center of the cam lobes.

Thanks for the suggestions. If the first idea doesn't fix it, I'll yank the cam and scrutinize it more closely. I'll also do your suggestion with the piece of metal to keep the cam from walking.

Thanks for all the support you guys. I'll check back this afternoon.

[GOSFAST]

Originally Posted by Walt Dupont--Me.

I spend alot of time ajusting valves, good thing I don't punch a clock. I usually ajust them about .002 tight and hook them all up, spin the cam over a few times, now check clearance one at a time, usually have to grind .001 or .002 it takes a long time but they will be perfect, I hate to have one valve going tick tick tick. Walt

Hi Walt, this is really some excellent advice, good post. Doesn't get any more accurate! While moving forward go back sporadically and check the already finished ones.

With this in mind I would just add one note, get this procedure totally finished BEFORE the crank/pistons/rods are installed. Much, much easier!

(Add) On most street rides we normally set them at .010" and .012" cold. We do pay attention to the cam-grinders recommendations however, but in the end we do make the final call.

Thanks, Gary in N.Y.

P.S. On a side note, it is one more reason to use the adjustable lifter platform, this is an area where "grinding-in" the clearances would really be difficult with a non-adjustable valve train. If you DON"T do these builds regularly the adjustables are the way only to go in my opinion. Also, with the non-adjustable platform should you "miss" one it becomes a major issue, worst case scenario with the adjustables is a fairly simple intake removal.

[crazycasey]

Are all the hollow bodied lifters the same diameter? I know they vary in length by several thousands of an inch. Perhaps I can find a longer lifter if I HAVE in fact gone too far on this wandering valve.

[rotorwrench]

This may have no bearing but I figured I would add it any way. A lot of the current manufacture cam followers are kind of an unknown.The follower face is profiled in such a way that there could be some inconsistencies with the process depending on what equipment is used in the manufacture of these parts namely the radius and how accurate the machining is. The follower may have a tendency to rotate in operation which might bring this to light but I wouldn't think it would make that large difference in the clearances. A worn follower might also be a problem due to uneven wear. Hardness could also be in question.

[JSeery]

"I think this has got to be what's happening, but what's the fix!? Shouldn't the spring hold the guide tight against the block? Anyway, I'll get out there in a little bit and check as you suggested, just not sure what to do from there."

Believe he is referring to the valve being sticky in the guide and not returning to the same position every time. Lightly tap the center of the valve to assure it is seated when you check clearance. Something has to be moving to get difference readings and it about has to be the valve in the guide or the lifter riding on something on the cam.

[JSeery]

Originally Posted by crazycasey

Are all the hollow bodied lifters the same diameter? I know they vary in length by several thousands of an inch. Perhaps I can find a longer lifter if I HAVE in fact gone too far on this wandering valve.

IF that is the case, that is not the best way to resolve it. Use a cap on the valve stem, or weld up the valve stem, etc.

[flatjack9]

I would lean more to the possibility that the lifter is a little sticky in the bore and not always returning to the same position.

[flatheadmurre]

If it´s just a couple of thousands that is missing touch it up in the valvegrinder.
If its a lot to short a lashcap.
You have checked so the valve is straight...stuff get dropped and may have been damaged ?

[crazycasey]

Originally Posted by JSeery

IF that is the case, that is not the best way to resolve it. Use a cap on the valve stem, or weld up the valve stem, etc.

Just curious why? I mean, I've got lifters in this motor ranging all the way from 1.699" to 1.740". That's a lot of range, and maybe it's not ideal, but it's what's in there. The one that's in the #4 exhaust bore is pretty short...a longer lifter would fix my problem. Just curious. I value everyone's input, I'm just the type to always ask "why".

Thank you!

[crazycasey]

Ok, well, I feel like a moron. The camshaft was walking, leading to ALL of my inconsistency. Now my valve clearances are WAY out of whack. I've got to make up 0.014" on the #4 exhaust. i can switch some lifters around and get within 0.005". Can I take that one valve back to the machine shop, have them touch up the valve face, and then re-lap it into the seat? I've already hand lapped ALL of the valves into the respective seats. Thanks again for all the advice.

[Mart]

Hey, at least you found what was causing it. We're all on a voyage of discovery every day.

Mart.

[chap52]

Finding the issue is a lot better than chasing several possibilities. Good news!

[GOSFAST]

Originally Posted by crazycasey

I got talked out of the adjustable lifters by the machine shop. He used a Chevy valve that was less expensive, but he said that there wasn't enough hardness in the tip of the valve to use IT with an adjustable lifter.

Hi Casey, that's the "lamest" excuse I've ever heard in my entire life of engine building, really?? That is strictly a sales pitch in my book, and you can tell whoever told you that, I said so! Not your fault at all, but very lame on him! An adjustable lifter, a stock length Ford valve, a good set of OEM springs, and all your problems disappear! Would've been so easy!

[QUOTE=crazycasey;1356530]Ok, well, I feel like a moron. The camshaft was walking, leading to ALL of my inconsistency. Now my valve clearances are WAY out of whack. I've got to make up 0.014" on the #4 exhaust. i can switch some lifters around and get within 0.005". Can I take that one valve back to the machine shop, have them touch up the valve face, and then re-lap it into the seat? I've already hand lapped ALL of the valves into the respective seats. Thanks again for all the advice.[/QUOTE]

I'm assuming you haven't gotten anywhere near the spring hgt/pressure requirements yet? I've posted up here many times against using the Chevy length valves and am in the middle (still) of setting up an "adjustable spring-seat-register" to deal with this very issue. Comp Cam's is holding us up at the moment with mfg the necessary spring seat locators for the Flathead guides.

Thanks, Gary in N.Y.

P.S. I would regroup and come up with some very accurate numbers and pay closer attention to the final installed spring hgts at the same time. Another "major" issue may be lurking! There's so much info to be gotten from this site I can't foresee having any real substantial problems! The available amount of knowledge up here is really immeasurable. "Good Luck"

[Greg58]

I had a similar problem on mine, I replaced a valve, guide and lifter a few years back and used the wrong clearance. Somehow I came up with .030 instead of .014. I got feed up with the tap and turned a valve lash cap down to .016 and installed it, all I took off was the intake. It sounds much better now