Valve Lash Esky. Cam

D

David Lien

Member
Old Friend Passed on Six years ago. before he left he brought me a couple of boxes of stuff. Which did include a reground 77 B Isky cam from Isky. The cam was still in the Isky box with all reciets and Papers. Cam is a 21 A 42-48 Flathead ford. The Cam card lists the valve lash .014 Ex. and .008 on the In, Which seems a little tight to me on the Intake valve. I am a little old and behind the curve, Sooooooo. does this seem right to the members of this board??? First owner ordered the Cam in 2008. He was going to put the cam into an old Pickup truck engine he was working on. Thanks. David
 
Valve lash is .014 for intake and exhaust, cold.

217700 21-A FORD MERC VB 77-B SOLID .325 .311 260 .014
817700 8B~A 32-53 FLATHEAD 77-B SOLID .325 .311 260 .014
 

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glennpm said:
Valve lash is .014 for intake and exhaust, cold.

217700 21-A FORD MERC VB 77-B SOLID .325 .311 260 .014
817700 8B~A 32-53 FLATHEAD 77-B SOLID .325 .311 260 .014
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Perhaps I'm reading the chart that you provided wrong but doesn't it indicate the lash setting as being HOT ?
 
Hot is incorrect. Lashes are cold. Isky has confirmed this in the past. Next to impossible to do it hot on a flathead.


Glenn
 
Hello All I took Petes advice and just got off the phone with Isky's support Dept. They advised me that the .008 on the intake valve lash was indeed correct, and happens many times with a reground Cam. It has to do with the smaller base Circle and the valve timing. The support person was fun and educational for this old fellow to talk with. Thanks Pete and all that answered my post. David
 
This can become a whole new subject of discussion, albeit a dull one.
I have several original Isky spec sheets, advertisements and original cam tags for the 77B.
Some date back a LONG time.
The oldest shows, in. .011 and ex. .013.
Another shows, .012 and .014.
Another shows, .014 and .014.
And now I hear .008 and .014 is the rage.

All the same cam grind??? Who knows? Did they change the masters or the literature for some reason?

More than likely, some of the spec sheets were put out by companies that were in the cam grinding business and were bootlegging Isky grinds with a similar one that had slightly different clearances. This was and is a common practice. The extent some people will go to for deception is interesting sometimes. Back around the 60's or so, Isky started putting box car one time seals around his cams to show it was an original. This worked fairly well till one guy figured out how to duplicate the seals so that idea went down the drain.

One thing for sure, if in doubt, run the cam in question through a Cam Doctor or degree it in the engine you intend to run it in.
 
All I can add is that I have done more than a few solid lifter cams, and have not seen one yet that calls for a clearance of less than .010".
 
Also, who knows when your particular cam was ground . . . off of what masters. I would probably use the .011 and .013 numbers that Pete gave you. Or the .012 and .014 . . . either ones will work just fine and you'll never be able to tell any difference between the two. Like TUBMAN said, I've never seem specs that called for less than .010 . . .
 
David Lien said:
... They advised me that the .008 on the intake valve lash was indeed correct, and happens many times with a reground Cam. It has to do with the smaller base Circle and the valve timing. The support person was fun and educational for this old fellow to talk with. Thanks Pete and all that answered my post. David
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Hi David,

I question the Tech's comment on a reduced base circle being the reason for the lower gap of .008"

The valves are adjusted with the each valve adjusted, gaps set, when on the "heel" of the cam. If the base circle is reduced in order to accommodate the re-grind, the gap at the heel would increase over what is was for a a standard and larger base circle. New longer push rods will be required for the intake valves unless you will be using adjustable lifters.

If the desire was to increase the valve open duration or lift, a smaller gap at the heel would do this but is not a requirement due to the reduced base circle.(Note that this is NOT a safe gap for exhaust valves since the time the valve is seated and cooled would be decreased.)

I've never seen a Ford Flathead with an gaps less than .010" as mentioned above. see the attached chart for example. Yellow highlighting made by me in the past.

You mention that the cam came from Isky in 2008 so not that old. Did it come with a cam card?

I agree with Pete and B&S but would use .014 & .014" myself.

"Also, who knows when your particular cam was ground . . . off of what masters. I would probably use the .011 and .013 numbers that Pete gave you. Or the .012 and .014 . . . either ones will work just fine and you'll never be able to tell any difference between the two. Like TUBMAN said, I've never seem specs that called for less than .010 . . ."
 

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The base circle is not dependent on the clearance ramp or vice versa. The design of the cam determines each. One important parameter of the design is that it must fit the diameter of the lifter.
The base circle diameter of the early 77B is .950.
You can not determine the running clearance by the base circle diameter.
 
Way back in the first post, he says the cam card furnished lists .008" for intake side of the house. I've no idea if that is right or wrong, but, do they make mistakes like that?? I suppose typos happen from time to time.

Talk to Ed! He's still kicking around the shop from what I understand ..
 
For the record I have set a cam with zero lash but that was on my harley and they determined that the cylinders would expand enough to give the valve adequate seat time. Due to the ball and socket push rod design you cannot get a feeler gauge in there.
Hydraulic lifters typically run zero lash because the adjust to the environment. My understanding was that it is important that the valve be allowed to fully seat in order for it to cool. I would take the previous suggestions and go with the larger clearance. It will not change any performance you will notice and your valves will be happier.
It's nice to see someone look at a number and question it when it seems unusual. Even if it were right for some reason it is what makes a good mechanic who is thinking and not just blindly going along.
 
I agree with that, it's definitely a healthy mix of "That can't be right" for people who can read, or read between the lines.

Beware people who think they are smarter than the people who actually designed and built it, however. Maybe. But, that's sure not the way to bet.
 
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