Questions and Answers
Camshaft Geometry
Q. Dear Vincent: For the first time ever, I'm rebuilding an engine. It's an 1982 Buick 231. My wife has even taken an interest and is working with me through each step. I'm installing a slightly high performance cam, and with the non-adjustable rockers.
I'm worried about valve train geometry. In order to degree the cam and check piston to valve clearance, I've disassembled two of my old hydraulic lifters and put washers in them for accurate measurements with all the precision instruments I've accrued. Upon tightening down the rocker shaft, I notice that there is absolutely no lash at all, and I'm afraid if I tighten down the shaft bolts all the way, I'll damage something.
Could you enlighten me on the proper procedure to check out valve train geometry on this type of engine. (The cam is a Comp Cams 252H grind with .425" lift).
Thank you so much, Joe
A. To be honest with you Joe, I never worried about valve geometry. I have always used the proper camshaft for the engine I'm working on and let the engineers worry about that. Even if you do get a measurement there's nothing you can do to change it.
The most important thing to worry about is the lift, you don't want it to exceed the lift of the stock camshaft. If it does, you run the risk of the pistons hitting the valves and that can ruin your whole day. All high performance cams do is alter the when the valves open and the duration they are open.
By putting washers inside the hydraulic lifters you are basically making them manually adjustable and some clearance is required. By how much, in this case, is not known. The hydraulic lifters will take up the clearance automatically, hence the term "self adjusting".
If you have the correct camshaft and lifters for the engine you should be okay.
Additional Information provided courtesy of ALLDATA
