Question on cam gear marks
 

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?

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

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.

Re: Question on cam gear marks
 

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.

Re: Question on cam gear marks
 

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!

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

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.

Re: Question on cam gear marks
 

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.

Re: Question on cam gear marks
 

http://www.autoblueprint.com/Article...ingCutaWay.jpg This is orientation for the grooves on a Chevy valve. Keeper goes in top groove as per picture.


R

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

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!):(

Re: Question on cam gear marks
 

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

Re: Question on cam gear marks
 

Those are $9 each - ouch!

Re: Question on cam gear marks
 

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

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

Re: Question on cam gear marks
 

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


R

Re: Question on cam gear marks
 

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...............

Re: Question on cam gear marks
 

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



R

Re: Question on cam gear marks
 

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

Compared to another, the cam gear is properly marked.