Box Stock

compression release "new" problem and solution.

S

sergeantclone

New member
Ok, found an odd compression release problem/solution and thought I had better post it for future searches....

valve lash wrong?.....Nope,
side cover gasket to thick?.....Nope,
timing wrong?.....Nope,

So guess what....The lash cap for the exhaust was sitting just a bit higher in to the "billet" spring retainer then the top of the valve stem, when it should have been sitting on the stem it self. So there was .030 play when the valve was being held open buy the release on the cam, and the pressure from the the piston would hold the valve closed. I had to shave down the lash cap.
 
There are two different valve lash caps being used in these engines,And guess what one does interfere with the keepers (IE pushes on the keepers not the valve stem)
 
The way that the valve rotator works is exactly as you have explained so there is nothing technically wrong. As the cap is pushed down it unloads the spring from the valve allowing vibrations to reposition the valve on the seat. The part you call a lash cap is actually referred to as a valve rotator. Now it may be sitting higher in the billet retainer if I remember correctly there is usually .010-.015" difference. In reality the cap should not be contacting the tip of the valve.
 
This is true in the non- positive type or release type valve rotators but with a Billet Aluminum retainer I feel this is a place where unnecessary wear could start and I don't think on these engines we have to worry about carbon building on the valve seats But you are 100% correct in their operation and in their intended applications they seem to work,but you must agree they are in no way as efficient as positive rotators
 
yep...it was the wrong lash cap. just a bit to wide and it was sitting on the billet retainer, not the keepers or stem. when I had the head off and I pushed in on the rocker arm, the valve had lots of free play. All is good now.
 
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