I am trying to make sure I will not have any clearance issues. I allready have the heads on and I have just discovered that retainer/ seal measurements should be taken anytime you alter valvetrain. I have stock 081 heads on my 88 LB9 TPI 305. I bought comp cam 981 valve spring, comp cam 1.6 rockers and felpro intake positive style intake and umbrella type exhaust seals. When I measure with my dial indicator I have come up short of even the stock lift of .415 and .430. I come up about .080 short, the thickness of the o ring, I looked in my helm service manual and it shows that the o ring when in it's groove on the valve stem is actually inside the retainer. I tried to push the seal into the retainer with a small screwdriver with the open access of my checker spring and could not get it to go in. So my question is how is the proper way to measure this without the o ring on the stem as it was where it should be? Is the positive seal supposed to push the o ring in? How does the o ring get where it is supposed to be? Not sure what to do any help would be appreciated.

 

It's been a long time since I've used the o-ring seals but if I remember correctly, you install the springs, compress them, install the retainer then the o-ring and keepers then uncompress the springs. If you put the o-ring on before the retainer, they'll never seal properly.

The exhaust valves don't really need seals other than the o-rings. Oil will never leak down the guides when the engine is running and the o-rings will keep the minimal amount of oil off the valve when the engine is off.

the intake valve however does need the seals as oil can be pulled down the guide as the piston is pulling the air/fuel into the cylinder.

As for measuring stem seal to retainer clearance, the spring should be removed. Clearance should be less than total valve lift. Lobe lift times rocker ratio equals total lift. If using a solid lifter, subtract the lash.

 

Thanks you very much I just got the first one using the method you described and I pulled the umbrella, there wasn't one on when I pulled the heads apart. I am now confident the o rings will work as intended thank you very much