Compression ratio
05-22-2017, 06:16 AM
#1
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Car: 89 Camaro RS
Engine: 350 TPI
Transmission: 5 Speed
Compression ratio
I just picked up a 85 vette TPI 350. It has 76cc heads on it with a compression ratio of 9-1. What would my compression ratio go up to with 64cc or 58cc heads with the stock pistons? Just wondering if I'd be able to run regular gas.
Thanks
Thanks
05-22-2017, 07:23 AM
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Re: Compression ratio
Going from your baseline numbers, 64cc heads would put you at 10.2:1. 58cc would be 11:1.
Are your current heads iron? If it's running ok with those, then 64cc aluminum heads with a larger cam could work for you with premium fuel.
Are your current heads iron? If it's running ok with those, then 64cc aluminum heads with a larger cam could work for you with premium fuel.
05-22-2017, 07:41 AM
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Car: 89 Camaro RS
Engine: 350 TPI
Transmission: 5 Speed
Re: Compression ratio
Yes, current heads are iron. Engine runs good now. Thanks, I have a set of ported 416s I was thinking of putting on but I just want to be able to run regular gas lol
05-22-2017, 10:05 AM
#4
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Re: Compression ratio
Sell the 461 heads to someone who wants 45 year old tech and save for something better and modern
05-24-2017, 05:15 PM
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Re: Compression ratio
First off, how do you "know" what your CR is now? 
Once you get past that, and all of the uncertainties that go with it that pretty much mean that ANY AND EVERY compression number posted on the Internet is WRONG one way or another, you're into some whole other world.
If these other heads are 416, they are 58cc, and on a stock 85 Vette short block, will require racing or airplane fuel.
If they are 461, they lack the bolt hole bosses for accessories, meaning that there's nothing there to drill bolt holes INTO, and none of that stuff (alternator, PS, AC) will bolt back onto the front of the motor with those there.
Whatever they actually are, sounds like you should sell them to the next "greater fool" (yes, if there's any one thing I've learned from my 40-some years in this hobby, it's that there's ALWAYS a "greater fool") and buy something you can actually use.
Once you get past that, and all of the uncertainties that go with it that pretty much mean that ANY AND EVERY compression number posted on the Internet is WRONG one way or another, you're into some whole other world.
If these other heads are 416, they are 58cc, and on a stock 85 Vette short block, will require racing or airplane fuel.
If they are 461, they lack the bolt hole bosses for accessories, meaning that there's nothing there to drill bolt holes INTO, and none of that stuff (alternator, PS, AC) will bolt back onto the front of the motor with those there.
Whatever they actually are, sounds like you should sell them to the next "greater fool" (yes, if there's any one thing I've learned from my 40-some years in this hobby, it's that there's ALWAYS a "greater fool") and buy something you can actually use.
05-24-2017, 05:19 PM
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Car: 67 ******mobile
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Re: Compression ratio
x3 ditch both sets and get something that moves air
those swirl ports are garbage even with work.
those swirl ports are garbage even with work.