Ryan Thompson

Okay, I can't get my head around why everyone says to keep our Lifter / Shims in the same location. They are designed to move in a circular rotation, as not to be worn unevenly by the cam or valve repeated contact.

It doesn't make logical mechanical sense to me.

If someone can come up with a logical reasoning as to why it is a good idea to keep them in their original home please see question #2.

#2. What if you had a "bad Lifter / Shim" and needed to buy a "brand new one". Would you have to throw the whole engine away? What would happen mechanically?

My theory is this is logic from push rod motors and is just something passed along from shade tree mechanic to shade tree mechanic. Maybe I am way off base and the collective knowledge on this amazing site will enlighten me.

I have some that are pitted on top and have 32 nice ones from the bad engine to choose from. Planning on taking them all apart and cleaning them.

Here are some pictures of my progress. Maybe I should be posting this progress in 1 thread, but like the idea of seperate thoughts and questions for searchability. I am guessing I am not the only one to have questions on these maters.

Ryan Thompson

These aren't the bad ones.


I know I will need to JB Weld the pitted spot


Pic of the motor / engine tore down

Speedtoys

Its a strong best practice...every shim will look like an LP record album, but with totally different tracks on it than another...there is a per-lobe very individual wear pattern.

If you have to change one, its not the end of the earth, unless you had deeper problems with that cam lobe to begin with.

Mrmerlin

best bet is to have the head welded JB weld is a last resort for this surface.
NOTE read the WSM before you do anything to the head so you can see how much surface is available for cutting

lifter and cam lobes all wear into each other.

swapping them will change the wear curves of the parts thus making the wear increase rapidly.

Ryan Thompson

The spot that needs filled is not a sealing surface of the head. It is by a water jacket that hits the gasket and does not go through. A machine shop I trust said, I could just leave it as is or jb weld the pitted spot. JB weld is good to 550 degrees. This head shouldnt get over 230 degrees.

Speedtoys

"A machine shop I trust said, I could just leave it as is"

Question what you trust.

Ryan Thompson

Here are the lifter shims in question

GregBBRD

Like said above, the cam lobes and lifters "wear in" together. There will be tiny variations of wear on each individual lobe and lifter....not something you are going to see with you naked eyes or feel with your fingernail.

I mark each lifter and return it to it's original position when I re-assemble, instead of shuffling them like a deck of cards and sticking them anywhere. However, if I find a bad lifter (very rare) I will replace that lifter with a new lifter.....there's nothing else that can be done, in that case.

In your case, if you have pitted lifters, the cam lobes are also going to be bad (The lifters are much harder than the camshafts. Wear always starts with the cam lobe, which then damages the lifters), so it doesn't really matter what lifter you put on which lobe.

Mix and match as you please.

Sell it quick.

Speedtoys

But remember, now the world knows how you didn't fix it.

Ryan Thompson

https://rennlist.com/forums/928-foru...corrosion.html

I also found this thread to backup what the machine shop and my logic was telling me. Again, not a sealing surface.

Ryan Thompson

So by looking at the lifters in question, I should ascertain the cam is bad. Correct?
It is on one cam that all the lifters / shims are worn. I have an extra cam or whole head from the bad motor (owned 928 3 weeks and found torque tube pulling on thrust bearing killing motor) . Should I look to swap the cam and lifters to this head or whole head swap?

Ryan Thompson

One side of the head the lifters are not pretty. PLEASE see question before this pic.

Ryan Thompson

I saw a thread where someone wet sanded the shim top. Bad idea?

Now I am more concerned about my cam being bad.

The Forgotten On

Used cams are inexpensive, and if unavailable you can have your existing cams welded and ground. No biggie there.

I would avoid sanding the lifter as you will reduce cam lift among other things.

Ryan Thompson

How can you evaluate a cam? I bought this car with a motor that had thrust bearing failure and bought this donor motor. I have 2 extra cams available. Also, should I be buying new shims for this cam? Problem is I didn't number the old motor's shims to the cam to be able to reuse.

Thanks so much for your help!