Small Block & Big Block Chevy Specific Mouse & Rat Motor Discussion & Conversions

valve clearance

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Old Jun 29, 2009 | 01:26 PM
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Well as a few of you may remember i didn't want to have to check valve clearance....well the piston hit the valve man it exploded the piston!!!...lol just kidding. I've decided to check it. My dads friend at his work was nice enough to loan me his spring removal tool so I can put some checking springs on there. The cam and the rest of my parts should be here by tomorrow and then I'll check it. Hopefully I'm fine on clearance, I'll keep my fingers crossed and I'll let y'all know the results. BTW is it .080 on exhaust and .100 on intake or the opposite of that???
The last guy really messed up my motor. First it was a hyd. flat tappet with ONE solid lifter by mistake and it flattened the cam and shavings went everywhere. Second time was with that huge cam that he said would work fine. Thats why I've just decided to do it myself, so I'm really hoping that combo works out, It sure would make me happy, I've spent so much money on it for nothing. Maybe 3rd times a charm. Wish me luck i need it ha
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Old Jun 29, 2009 | 05:29 PM
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PTV clearance are opposite of what you have mentioned. That's a good rule of thumb. I ran Super Stock Hemi's alot tighter than this before turning to 9400RPM's. good luck.
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Old Jul 1, 2009 | 08:13 PM
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I think you'll be good and happy this time around and I'm glad you decided to do the right thing a check. Good luck and have fun!
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Old Jul 3, 2009 | 04:09 PM
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well turns out that it did not clear:/

but the good knews is its only guna be $100 to get the pistons fly-cut so thats not too much of a set back. i sure am glad i checked though. whewww that would have been a disaster!

i take it tuesday to get them cut so i should be close to being put together by the weekend, and ill post some pics when im done
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Old Jul 4, 2009 | 11:45 AM
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how much clearance did you have? if any.
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Old Jul 4, 2009 | 04:53 PM
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Originally Posted by android91chevy
well turns out that it did not clear:/

but the good knews is its only guna be $100 to get the pistons fly-cut so thats not too much of a set back. i sure am glad i checked though. whewww that would have been a disaster!

i take it tuesday to get them cut so i should be close to being put together by the weekend, and ill post some pics when im done
Just curious. Did you check it with the timing chain installed and roll the engine over by hand or did you bring the piston to TDC then the valve to max lift to measure? If you did it the second way, it's wrong. The piston is not at TDC at max lift, you need to check it with the cam coupled to the crank via the timing chain. I'm just surprised it didn't clear is all. Just trying to save you $100 and some compression, because bigger valve reliefs equals less compression which is what you were looking to increase in the first place!
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Old Jul 4, 2009 | 05:32 PM
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Originally Posted by kenSS
how much clearance did you have? if any.
it did not clear any, the intake valve made contact.
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Old Jul 4, 2009 | 05:38 PM
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Originally Posted by fast01
Just curious. Did you check it with the timing chain installed and roll the engine over by hand or did you bring the piston to TDC then the valve to max lift to measure? If you did it the second way, it's wrong. The piston is not at TDC at max lift, you need to check it with the cam coupled to the crank via the timing chain. I'm just surprised it didn't clear is all. Just trying to save you $100 and some compression, because bigger valve reliefs equals less compression which is what you were looking to increase in the first place!

no the timimg chain was installed along with the checking springs, and i rolled it over by hand....the intake is the only one that hit. it just barely touched on both sides of the valve relief, so if the relief was just a little bit wider it woulda cleared. but ya its really a bummer, how much compression do you think ill lose?
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Old Jul 5, 2009 | 12:47 PM
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Hmmm, after reading through your posts again, it sounds like you got bit by the bigger 2.05" valve. That's one thing I didn't think of when you told us which heads you were going with. .03" is a lot of clearance to lose, especially when the valve notches were most likely designed with a 2.02" valve in mind. In hind sight, a 2.02" valve probably would've fell dead center in the center of the valve relief (the deepest part) and clearance would've been fine. Oh well, no harm, no foul! As far as compression goes, you'll lose about .1 (1/10) of a point for every 1cc you increase the valve reliefs. Nothing too significant.
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