Stock Cranking Compression

car9fan · 01-01-2006, 10:42 AM

Can someone tell me whats the normal/stock cranking compression is for a 302, Thanks Ronnie

Gearhead999 · 01-01-2006, 03:00 PM

It really depends on the year. Cranking speed, compression ratios and cam timing effects the total PSI.

I'd look for something in the area of 125-150 PSI. More important is the variance between cylinders. Should be 10-15% maximum. And any cylinder way off, like everything is 130-135 PSI and one hole is 90 PSI. That's not good. Then you have to determine, why?? Squirt some oil and do it again. See if it comes up. If it does you have a ring problem, if not its a valve problem, etc.

Good luck, Happy New Year !!!

car9fan · 01-01-2006, 05:54 PM

Thanks i got 165-170 psi on all cid.s but the motor is suppose to have 10.1 compresion, Thanks Ronnie

Gearhead999 · 01-02-2006, 03:53 PM

Sounds OK to me. Compression ratio isn't a factory because of valve timing, which will bleed static pressure off.

car9fan · 01-02-2006, 05:19 PM

I had to buy a new short block and it was supposed to have 10.1 compression but i thought it have more cranking psi., Thanks for the reply, Ronnie

01-01-2006, 10:42 AM	#1
car9fan CAR9FAN Join Date: Mar 2004 Location: m.d Posts: 103	Stock Cranking Compression Can someone tell me whats the normal/stock cranking compression is for a 302, Thanks Ronnie __________________ MY HOME PAGE

01-01-2006, 03:00 PM	#2
Gearhead999 Registered Member Join Date: Sep 1998 Location: Oviedo, FL Posts: 992	Re: Stock Cranking Compression It really depends on the year. Cranking speed, compression ratios and cam timing effects the total PSI. I'd look for something in the area of 125-150 PSI. More important is the variance between cylinders. Should be 10-15% maximum. And any cylinder way off, like everything is 130-135 PSI and one hole is 90 PSI. That's not good. Then you have to determine, why?? Squirt some oil and do it again. See if it comes up. If it does you have a ring problem, if not its a valve problem, etc. Good luck, Happy New Year !!! __________________ "Support our Troops" Dave 1968 Cougar 2004 Thunderbird 2007 F150 Harley-Davidson, SuperCrew 1986 LTD 1997 Ranger 1992 Honda Civic

01-01-2006, 05:54 PM	#3
car9fan CAR9FAN Join Date: Mar 2004 Location: m.d Posts: 103	Re: Stock Cranking Compression Thanks i got 165-170 psi on all cid.s but the motor is suppose to have 10.1 compresion, Thanks Ronnie __________________ MY HOME PAGE

01-02-2006, 03:53 PM	#4
Gearhead999 Registered Member Join Date: Sep 1998 Location: Oviedo, FL Posts: 992	Re: Stock Cranking Compression Sounds OK to me. Compression ratio isn't a factory because of valve timing, which will bleed static pressure off. __________________ "Support our Troops" Dave 1968 Cougar 2004 Thunderbird 2007 F150 Harley-Davidson, SuperCrew 1986 LTD 1997 Ranger 1992 Honda Civic

01-02-2006, 05:19 PM	#5
car9fan CAR9FAN Join Date: Mar 2004 Location: m.d Posts: 103	Re: Stock Cranking Compression I had to buy a new short block and it was supposed to have 10.1 compression but i thought it have more cranking psi., Thanks for the reply, Ronnie __________________ MY HOME PAGE

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