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-   -   LT 1 350 valve to piston clearance (https://classracer.com/classforum/showthread.php?t=64801)

Kdw1403 01-01-2017 12:41 PM
LT 1 350 valve to piston clearance
 
What is minumun valve to piston clearance? i have .100 on intake and .60 on exhaust. I am a little nervous about exhaust side. Is it legal to cut the exhaust valve pocket on the piston just a little? nhra stocker

Bob Gullett 01-01-2017 01:14 PM
Re: LT 1 350 valve to piston clearance
 
Is that checked with checker springs or the regular springs?

Dan Fahey 01-01-2017 01:42 PM
Re: LT 1 350 valve to piston clearance
 
Quote:
Originally Posted by Kdw1403 (Post 523452)
What is minumun valve to piston clearance? i have .100 on intake and .60 on exhaust. I am a little nervous about exhaust side. Is it legal to cut the exhaust valve pocket on the piston just a little? nhra stocker
I do not think so.
265 55 Chevys sure wish they can notch their flat pistons to get some valve tolerance.

D

Ed Wright 01-01-2017 02:10 PM
Re: LT 1 350 valve to piston clearance
 
Quote:
Originally Posted by Dan Fahey (Post 523456)
I do not think so.
265 55 Chevys sure wish they can notch their flat pistons to get some valve tolerance.

D
Having raced 265" '55 & '56 Chevies, we damn sure flycut our flat top pistons for valve-to-Piston clearance. Mine was down 4 times by NHRA, three national records & once was protested, passed every time.

Alan Roehrich 01-01-2017 02:15 PM
Re: LT 1 350 valve to piston clearance
 
No, it is not legal to cut the valve reliefs on pistons in NHRA Stock Eliminator.

I would probably consider 0.060" piston to valve clearance on the exhaust to be the minimum safe clearance, if it was properly checked to begin with, and you have very good valvetrain control.

MR DERBY CITY 01-01-2017 02:29 PM
Re: LT 1 350 valve to piston clearance
 
Quote:
Originally Posted by Ed Wright (Post 523460)
Having raced 265" '55 & '56 Chevies, we damn sure flycut our flat top pistons for valve-to-Piston clearance. Mine was down 4 times by NHRA, three national records & once was protested, passed every time.
Ed, we are talking STOCK eliminator.....Alan is correct. I might add just watch yourself in the water....

Ed Wright 01-01-2017 03:44 PM
Re: LT 1 350 valve to piston clearance
 
Quote:
Originally Posted by MR DERBY CITY (Post 523463)
Ed, we are talking STOCK eliminator.....Alan is correct. I might add just watch yourself in the water....
I apologize. The Stock rules are different enough from when I ran Stock with that '56, I should have kept quite. About all he can do legaly is move the cam.

I don't get the remark about water?

TOSTO RACING 01-01-2017 03:55 PM
Re: LT 1 350 valve to piston clearance
 
I think he is referring to don't let it get away from you on a burnout. People tend to over rev a car in the water box.

As for vtp like Alan said above .060 .065 exh would be as tight as I've ever ran and it was okay for me. The intake is more forgiving. if I were you I'd advance the cam and get yourself some more exh clearance and less int in my opinion if you are worried about it .

Good luck with it.

Ed Wright 01-01-2017 04:01 PM
Re: LT 1 350 valve to piston clearance
 
Quote:
Originally Posted by TOSTO RACING (Post 523468)
I think he is referring to don't let it get away from you on a burnout. People tend to over rev a car in the water box.

As for vtp like Alan said above .060 .065 exh would be as tight as I've ever ran and it was okay for me. The intake is more forgiving. if I were you I'd advance the cam and get yourself some more exh clearance and less int in my opinion if you are worried about it .

Good luck with it.
Need to use a rev limiter in the water. I run .040" on the intake side a lot, have run .035" and they never touched. Had clean intake pockets. No carbon. I've never run less than .065" on the Ex side. Right now, mine has .040" & .070". Nothing touches.

Dan Fahey 01-01-2017 05:31 PM
Re: LT 1 350 valve to piston clearance
 
Curious. Why more Clearance on the Intake vs Exhaust. ?


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