I was trying to measure my Piston to valve clearance this weekend on the solid roller I am putting in.

I tried putting piston at TDC, and zero lashing. Then I pushed down the valve against a checker spring and inserted .100 thickness of feeler gauges.

That really didnt work because they kept falling out while i was rotating the engine and were rubbing not only on the stem, but also retainer.

I next went to TDC, and inserted the feeler gauges first (.100" worth) and zero lashed it. I then removed the feeler gauges, counting turns of the lock nut on the rocker arm to get back to true zero lash. I then added that many turns past zero lash opening the valve (should have been .100 more open).

Here is the question. I only measured 3/4 a turn for .100 of an inch on my rocker nut.

On shoebox's site, for 7/16 studs he has a 1/2 flat = .00416, 6 flats per rotation.
.00416 x 2 = 1 flat = .00832
.00832 x 6 flats = 1 rotation = .04992

Using his numbers would mean 2 full turns for .100" . I cant imagine I would have been that far off.

 

Did you put some clay or playdoh in the piston valve reliefs and spin the motor over? If you measure that thickness after you do it you will be pretty close. RMRE has a really in depth way of doing it but it requires special valves and a ton of work.

Bret

 

Put the clay in the v reliefs and make smooth with the top of piston. Put oil or baby powder on the clay(to keep it from sticking to valve). adjust valves,roll engine twice,remove head,cut clay and measure and that is your P/V clearance..080 I-.100 E min.

 

Heads are still on the car. Trying to avoid pulling them to do the clay method.

 

Ok,put a degree wheel on it and start at 40*BTDC and check it every degree like you were with the soft springs and a dial indicator and pushing on them until ya reach 40*ATDC.This is with both valves adjusted and both with soft springs.
Do it two rev's to get the overlap cycle ,and make sure ya find "0" correctly.

 

OK that makes sense.

Where is the best place to set up the tip of the dial indicator? On the flat (non concaved) part of a retainer?

 

Yea, any place that will give ya the measurement the valve travels to the piston.

 

thank you larry and bret

 

Anytime