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Author Topic:   Checking Valve Clearance
o5racer
Member
posted September 21, 2003 06:51 PM
I was thinking about going up a little in cam lift for next year and was wondering what the best way to check piston to valve clearance.


ryan
Member
posted September 21, 2003 07:06 PM
I think you need to go down to a much smaller cam maybe around stock size. No need to try and go faster you are fine where you are at. lol


outlawstock17
Member
posted September 21, 2003 07:57 PM
check it with modeling clay. install a wad of clay in the valve notches on the piston, install the head, gasket, push rods and rockers lashed correctly and roll the engine over 2 revolutions and remove the head and look at the clay. you just need to do this on one cylinder.


o5racer
Member
posted September 22, 2003 12:22 AM
Funny Ryan. I thought about that but changed my mind.

I thought about the clay idea. I was reading somewhere about using real soft springs and a dial indicator. they checked how much farther the valve would open before it hit the piston. anybody got any info on this? how much clearance should i have?

dirtracer7
Member
posted September 22, 2003 06:54 AM
they say .100 without head gasket.


dirtbuster
Member
posted September 22, 2003 01:08 PM
I think the Chevy power book says 0.080 intake and 0.100 exhaust minimum, and i beleive that is with head gasket.

I have heard with good tight clearances on your bearings and cylinder walls you can shoot for .010 clearance for every 1000rpms.

sdhnc29
Member
posted September 22, 2003 01:40 PM
Yes it's simple . Use the light springs like you already mentioned , and an old head gasket that is already crushed . Take a dial indicator and set up on your exhaust valve , set it up on the retainer so the rocker can run on the tip of the valve like normal . Set up the rocker at zero lash . Turn the engine over by hand until you are on the overlap of the cam . At this point push the valve that your indicator is set up on down until it touches the piston . Watch your indicator , and rotate the engine until you find the tightest spot . Let the valve come back up , zero your indicator , compress the valve until it touches the piston , read how much valve to piston clearance you have , add your lash to this number and your done. Repeat this process on the intake valve . you should have a bare minimum of .080" intake valve to piston clearance , and a minimum of .110" on the exhaust . Be sure that your cam is degreed properly before checking .

Steve

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


o5racer
Member
posted September 23, 2003 03:32 AM
Thanks alot guys for your help.


nw15x
Member
posted March 10, 2004 09:02 PM
was reading this post and just want to confirm on the measurement. If I measure without gaskets and the .065 on intake and .075 on exhaust then I would add gasket thickness of .035 for a .100 intake/.110 for exhaust, then add .020 for lash and the final value is .120 intake/.130 exhaust. Steve is this correct based on your message...


sdhnc29
Member
posted March 10, 2004 11:10 PM
You are correct!

Steve

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780
Check out my other business at www.solemnvow.com A special thanks to jammin for the awesome job he has done for me on this site!!


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