Valve lash for 59A style camshaft

[GB SISSON]

Originally Posted by RandyMettler

I am reading past posts for research. I believe I have the adjustable style tappets as they have an adjusting nut. I have noticed that some of the tappets nuts are quite loose. I read at least one post that stated this is a problem resulting from over adjusting and needs to be addressed. I looked for the "light in the lifters" by GB SISSON post but could not find it. I also web searched an found an article that stated tappets and cams are a matched set and it is not a good idea to just replace few tappets that are collapsed. It will eventually destroy the motor. I don't know if this is true and frankly don't know if flathead tappets can even collapse? I am new to all this. If the loose nut is a problem can I use green locktite for a fix? I read a post that suggested this as a fix. The other thing is when I am adjusting a verifying lash, some of the tappets have to be pried down with a screw driver to get the guage between the valve and tappet.

Below is a link to a site, if you haven't seen it before, that has a chart with comprehensive specification of just about every camshaft you can buy for any year flathead. Some of the listed specs are referenced from original ford drawings. Stock 37-48 78-6250 cam is listed at .011. and .015. This conflicts all the information I have read. I will call them after the holidays to verify where the drawings came from. This site goes very deep into cam design and function. Its worth a look.
I am thinking of setting lash bases on the site .012 and exhaust at .015

https://www.tildentechnologies.com/C...rformance.html

I remembered my post about the loose lifter threads was actually titled 'loose in the lifters'. I had it mixed up with an old out of date expression 'light in the loafers'.

[Drbrown]

JSeery's advice a way to go re tightening the thread fit. I also read someone used a punch to "upset" (disturb) the threads on the adjustable bolt to tighten the fit, but suspect that might produce more unpredictable results.

Regarding "prying down the tappets" to get a gauge in, the tappets obviously shouldn't fit too tight in their cores .... be sure they're not distorted and binding.

[RandyMettler]

Thank you JSerry for your help.

[RandyMettler]

Thanks JSerry and all others who have taken the time to give me help. The tappet intake lash reading before I adjusted them were all over the place. One was as high as 0.20

Regards, Randy

[Jim Brierley]

The small holes in each lifter boss are for inserting a drift punch into in order to keep the lifter from rotating while adjusting them. This is not usually done for a stock cam but I would measure the existing clearance and assume that is close to where it should be. Setting the exhausts too close might result in burnt valves, too loose will be noisy. Good luck!