Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

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alnukem
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Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by alnukem »

Hi & Thanks! One of my Favorite Cars got the Engine Blown. It is a 79 L-82 Vette 3.70 Gear Stick car. I am not looking to be the fastest on the street, just a cool nostalgic ride that runs well. I am trying to decide whether a rebuilt .030 over L31 or a Dart 372. But, I want to run it on 87 Octane. I have a set of Edelbrock 170 E-Tec 64cc heads, but like the flow of the AFR Vortec heads. If I do the vortec block compression, it figures out to 9.4, with the 4.125" Dart bore, it figures out to 9.55. I am using forged pistons, good rods, shooting for "perfect quench", dual plane intake & it has a good cooling system with electric fans. The cam will be specced by Mike Jones. Is this too much compression for 87 Octane? Is one of these chambers more forgiviing? Thanks again!
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by F-BIRD'88 »

To run 87 octane you will need to run compromised some what retarded WOT timing at that CR.
If you want it to last.. There is no free lunch.
Real world operating conditions vary a lot on the street.

Good gas is like good motor oil. Pay me now or pay me later.
1980RS
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by 1980RS »

Since it blown application I would put the cam on a 114° LCA for sure to help with being able to run the low octane fuel.
Monza355
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by Monza355 »

1980RS wrote: Sat Sep 18, 2021 2:24 pm Since it blown application I would put the cam on a 114° LCA for sure to help with being able to run the low octane fuel.
I take it as the current engine is blown up.
He mentioned he has a dual plane intake on it
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by lefty o »

9.5:1 with aluminum heads on 87oct, its absolutely doable. wrong choice of cam can definately get you into trouble with it, but this is no where near a danger zone.
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by F-BIRD'88 »

So how much is Mike Jones going to need to lame down the camshaft to make this work?
Is that all it takes? Give it a less than or much less than optimum camshaft?

Get your 87 octane camshafts here. Hurry!
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Re: Compatability of 9.55 compression, AFR 65cc Chamber & 87 Octane?

Post by lefty o »

9.5:1 with an aluminum head, wont have to be very tame at all.
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