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Piston to Valve Clearence Question

Posted By: 383BeepBeep

Piston to Valve Clearence Question - 10/29/09 05:44 PM

I know the rule of thumb is .080" for intake on a steel rod engine. Here is my problem/question. I took the 452 heads off of my 383 and put on a set of eddy 84cc heads. Did a valve/piston check with checking springs and dial indicator. Exhaust is fine. Intake is terrible at 5* ATDC to 10* ATDC. Now the way I see it the intake valve is chasing the piston, and shouldn't be a problem. Should I change my way of thinking or button her up? What do you guys think?
Posted By: DaytonaTurbo

Re: Piston to Valve Clearence Question - 10/29/09 06:07 PM

How did you check it? Did you install the cam and time it correctly, then do the clay on the top of the piston and rotate the crank? Because cam timing greatly affects p/v clearance.
Posted By: 383BeepBeep

Re: Piston to Valve Clearence Question - 10/29/09 06:27 PM

When the engine was first built the cam was installed straight up. I would prefer not to retard cam to make this work. All measurements are being done with checking springs and a dial indicator. The worst of the measurements is .010" @ 6* ATDC
Posted By: sg66mopar

Re: Piston to Valve Clearence Question - 10/29/09 06:32 PM

I you're running a roller cam you should check with the springs you'll run. Heavy roller cam springs can cause a lot of deflection in the valve train and your current numbers could go out the window.
Posted By: RapidRobert

Re: Piston to Valve Clearence Question - 10/29/09 07:02 PM

Quote:

What do you guys think?


With .080" being the mininmum at any point in the cycle, .010" is not acceptable. Not sure the best way out whether flycutting (enough cutting might change balance too far) A thicker gasket would cost CR (& possibly your quench). Smaller cam. When you solve it if your cam gear has (3) keyways I'd suggest checking the VP clearance in all three positions so later on if you experiment w cam timing the PV clearance will already be dealt with. I prefer light springs and a dial indicator rather than light springs and clay (less mess/more accurate & a direct reading) & check the radial clearance between the perimeter of the valve and the eyebrow in addition to the depth. Good luck & holler back with how it turns out.
Posted By: Dodgem

Re: Piston to Valve Clearence Question - 10/29/09 07:23 PM

Your not using clay?
I would check the degree on the cam. Is there no valve notches on your pistons??
Posted By: MoparforLife

Re: Piston to Valve Clearence Question - 10/29/09 07:33 PM

Quote:

Your not using clay?
I would check the degree on the cam. Is there no valve notches on your pistons??


The way he is doing it much more accurate than clay.
Posted By: 383BeepBeep

Re: Piston to Valve Clearence Question - 10/29/09 08:13 PM

Thanks guys for replying. As for the pistons, they are 2315's, which do not have reliefs in them. And this is a zero deck engine. I have decided to not use the eddy's right now. The 452's are going back on.
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