piston/valve clearance question - Team Camaro Tech
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post #1 of 5 (permalink) Old Mar 12th, 10, 08:51 PM Thread Starter
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piston/valve clearance question

If I dont have any solid lifters is there another way to check valve to piston clearance? from what I hear I should be fine but I just want to be sure. Its a 350 with a comp 268xe cam and flat top pistons, and stock rockers. Thanks.

1967 coupe
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post #2 of 5 (permalink) Old Mar 12th, 10, 09:12 PM
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Re: piston/valve clearance question

I use a pair of very light "checking springs". They're just enough to hold the keepers in place but too weak to collapse the hydraulic lifters. Zero the dial indicator on the retainer and push the valve down till it touches the piston. You need to turn the motor and check the clearance every couple of degrees to find the minimum. Not as accurate as the clay on the piston method but you don't have to pull the head.
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post #3 of 5 (permalink) Old Mar 12th, 10, 10:47 PM Thread Starter
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Re: piston/valve clearance question

Thnaks for the reply.I'm in the middle of the rebuild right now so the heads are still off.

1967 coupe
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post #4 of 5 (permalink) Old Mar 13th, 10, 09:40 AM
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Re: piston/valve clearance question

The Valves are closet to the pistons upon opening and closing. When assembling the engine as in your case, mock the assembly using #1 cylinder, Spray WD40 on Valves and place a rolled bead of Pumbers Putty "X'd" across the the Valves Reliefs of the Pistons. Roll the engine over TWICE. Dissect the Putty with a Razor and measure with a Caliper.

When Checking P to V Clearance on an assembled Engines you use TEST Springs with a Dial Indicator on the Rocker Tip and Check the Clearance by pushing down on the Valve turning the Engine evey 2 degrees through TDC.

You should not have to worry about P to V Clearance with a 268 Cam; however, it is Duration that effects P to V Clearance as apposed to Lift. Advance and Retarding the Cam Position will Generally change the Clearance by .010" for Every 2 Degrees; such that, if you advance the cam by 2 degrees the Intake Valve will be .010" Closer and the Exhaust Valve .010" further.

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post #5 of 5 (permalink) Old Mar 13th, 10, 05:14 PM
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george
 
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Re: piston/valve clearance question

[QUOTE=Z15CAM;1393998]

When Checking P to V Clearance on an assembled Engines you use TEST Springs with a Dial Indicator on the Rocker Tip and Check the Clearance by pushing down on the Valve turning the Engine evey 2 degrees through TDC.

Just like to add..this measurement is taken during the overlap period +- 10* of tdc exhaust stroke.This is the only time both intake and exhaust valves are open at tdc.

George
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