What 350 sbc heads to choose for 87 octane - Hot Rod Forum : Hotrodders Bulletin Board
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Old 09-18-2008, 07:22 PM
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What 350 sbc heads to choose for 87 octane

Hello guys I am trying to figure out what heads wise for combustion chamber size to get to run on 87 octane. I am going to build a 350 next year and here is my build so far.

I am going with a 350 4 bolt with a cast steel crank and forged rods with hypereutectic flat top 4 valve relief pistons. The cam I am looking at is a comp xtreme engergy xr 270 with 218//224 duration @50 with 495/502 lift. The intake will be a weiand street warrior intake with a idle to 5500 rpm range.

The heads I was looking at was the world product SR heads. They come in either 76cc or 67cc combustion chambers. Summit also makes iron heads almost the same with 64cc comubstion chambers and I am wanting to make around 325 hp and be able to run on 87 octane. With the 64 cc I would be around 9:8 to 1 and with 76cc I believe it would be around 8:7 to 1.

What would be the right ones to get? Thanks Eric

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Old 09-18-2008, 07:32 PM
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check out the 70cc Edelbrock aluminum performer head.

what is the piston deck height? -0.020" can add as much as 4cc to the chamber.

gears, stall, car weight, environmental conditions, and cooling system performance also determine detonation sensitivity.
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Old 09-18-2008, 07:41 PM
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check out this site

http://www.projectpontiac.com/ppsite...nt/view/16/30/

shoot for 9.25:1 cr with that cam which should make around 7.3 dcr.

A friend of mine runs 87 octane with a compcam 260 and 9.4:1 cr, 2.87 gear, stock stall, 3000 pounds, and runs hot (200F). Pings every once in awhile.
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Old 09-18-2008, 07:53 PM
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Well it will be in a 96 s10 with be with a 350 turbo tranny with a 2100 stall converter with either 3.42 or 3.73 gears. Its whats in the s10 from factory rear end wise. I am figuring that is whats in it. It will be my daily driver to work and back. Thank Eric
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Old 09-18-2008, 09:46 PM
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You can't go wrong with a set of vortec heads, they work well with 87 octane on my camaro. I have the XE-262 (218/224 @ .050") and 9.3:1 compression, I only run 87 octane. Never runs hot or pings either but I would say if it happens to you that would be because of other problems!
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Old 09-18-2008, 10:42 PM
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Eric, one of the ways to control detonation (pinging) in a motor is to minimize the distance from the top of the piston crown to the underside of the cylinder head with the piston at top dead center. This dimension is called squish by some people, quench by others, but it means basically the same thing in the context of measuring the space between the piston and the head.
Read this tutorial from Speed-O-Motive and pay particular attention to "quench"....
http://www.speedomotive.com/t-showbymodel.aspx
These guys have been building motors since I was a kid and they know what they're talking about.

Oh and Eric, don't choose the cam before you have everything else nailed down. It makes you look like a noob.
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Old 09-20-2008, 09:20 AM
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Why use an octane rating as a center point for a build? Sure you can build it to run on 87 octane with some bathtub chambered heads and an itty bitty cam but you may not be happy with the end result. There are prolly 80 or so heads you can choose from for the sbc. The Vortec is a good suggestion in any case. Think hard about what you really want, about your trade offs and what you want to accomplish before you make any decisions. Sometimes we are penny-wise and dollar-foolish JMO
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