Quick PTV question????

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Jan 13, 2008 | 10:41 PM

CriminiSS

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Quick PTV question????

Hey guys, I am currently running PRC 5.3 2.5's and a TR230(230/224 .575/.563 111 LSA) and was wondering if I would run into PTV problems if I deck the heads .010 and use the cometic .040 gasket. The intake valve is a 2.02 if that helps. Any advice would be great and thanks!

Also wondering what the Part # for the cometic I need. its 3.910 bore correct?

Tom

Last edited by CriminiSS; Jan 14, 2008 at 01:26 AM.

Jan 14, 2008 | 08:05 AM

CriminiSS

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Can anybody help here? How about a .045 gasket and .010 off the head

Jan 14, 2008 | 08:14 AM

jshelton2006

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can you measure ptv clearance now??? if so just subtract about .30" from it and if that gives enough clearance you should probably be fine, but should still check it after milling the heads. 3.910 bore is correct.

Jan 14, 2008 | 08:42 AM

BOWTIE

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I would not think so, but you should check. that would most likely be right on the limit for the intake (for the .080 recomended clearance), the exhaust should clear easy. Do you know how much advance your cam has or what you plan to install it at. If I remember reading it correctly, the more you advance the cam the closer the intake will be.

Jan 14, 2008 | 01:35 PM

JPH

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Quote:

Originally Posted by CriminiSS

Order a Cometic #C5475-040 (2) that is 3.910/.040 and as far as your PTV is concerned, it should clear, but you will need to check it though. Your milled heads, thinner head gaskets, aftermarket valves worry me a little, but it should clear.

Jan 14, 2008 | 06:31 PM

CriminiSS

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Thanks for the help guys. I just ordered the .040 Cometic but have yet to mill my heads. I probably wont do it just to be on the safe side.

Jan 14, 2008 | 08:46 PM

hammertime

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Quote:

Originally Posted by CriminiSS

Thanks for the help guys. I just ordered the .040 Cometic but have yet to mill my heads. I probably wont do it just to be on the safe side.

How thick are the gasket you are currently running. Stock MLS are usually about .053, so milling .010 and removing .013 from the gasket leaves you a little more than was stated above.

Rather than rely on someone to give a yah or nay answer, it is advisable to measure the clearance you have now, since you are not changing cams or ICL. You just need a degree wheel, an adjustable pushrod, checking springs and a dial indicator. Pull your plugs and unbolt all the rockers. Replace the #1 intake and exhaust valvesprings with the checking springs (but really the intake is the only place where you should have any problems with that cam!)

Setup the adjustable pushrod at your current length - current lifter preload to see where you end up. Then starting about 20* BTDC, use the dial indicator to measure how far the valve is from the piston by depressing the retainer. Keep track of the results, and measure every two degrees or so until 20* ATDC. We're looking for .080 minimum intake clearance and .100 exhaust. Really, to accomodate the milling and thinner gaskets, you want .105/.125.

Also, while you are going through all this trouble, if you've had any valvetrain noise (the sewing machine sound we always hear about) it may not be a bad idea to see if your pushrods are/will be the proper length. Ideally, your proposal adds .023 lifter preload without changing the pushrod, but you'll have the necessary tools out to verify.