I just finished the break-in on a newly installed Compcams camshaft and lifters on my 69 302. After finishing the 30 minute break-in period and fine tuning of the car I noticed some lifter noise during the first drive. I pulled off the driver side valve cover to adjust and noticed that on #7 exhaust valve that the valve would not stay in the open position (I'm following the adjusting procedure that when the exhaust starts up then adjust the intake valve). The valve spring pushes against the push rod and it looks like the lifter lets down (not all the way, but some). Oil is coming out of that push rod just fine during operation.

So the question: is this normal or do I have a lifter failure in the works? Or should I give it some time for the lifter to possibly pump up to good hydraulic pressure?

Thanks everyone

Cam specs:
Gross valve lift: Intake .512, Ex .531
Duration @ .050: Intake 226, ext 234
lobe separation 111.0


Running with Edelbrock performer RPM heads, intake and 600cfm carb.

 

mmmm... "does not stay open".. not quite getting the concept...

if the engine stops in a position where the valve is open, valve spring pressuere will over time "colapse" the lifter, and the valve will move toward closed a little as the oil is pressed out of the lifter.

Might try useing a dial caliper to check for lift, etc.

 

This is lifter leak down, and sounds unusually fast. If you have Rhodes lifters, this is normal, they leak down immediately, faster than you describe.

The cycle rate even at idle should make this unlikely to be a problem. Of course, this is a good point to readjust the valves.

 

Thanks for the replies.

It looks like it was lifter leak down. I pulled the old valve covers off the shelf that I had cut the tops out of and ran the engine at idle. No problems with the lifters, but I did find one that was not quite snug. Problem solved.