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Old 06-18-2008, 07:28 AM
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How much hp with these changes to my SBC?

Currently running 76cc GM iron heads (462624 casting) with H618CP domed pistons and Performer RPM cam. Current CR is 9.38:1 and quench area is 0.063". Heads are currently off and I'm considering one of the following options...

#1 Mill heads (just to be sure they're 100% flat) and install Felpro 1094 gaskets (0.015" compressed). New CR will be 9.9:1 and quench area will be 0.040"

#2 Replace heads with Edelbrock Performer RPM with 70cc chambers and install with Felpro 1094 gaskets. New CR would be 10.7:1 and quench area would be 0.040"

How much extra do you think I'd gain with both options. New heads aren't cheap, so I don't want to go that route if the gain is going to be relatively small. From the very helpful folks on here, I now know that newer/better heads like Vortecs or the newer Dart heads aren't suitable for my application due to heart/kidney-shaped chambers and my domed pistons.

Thanks,
Ian.

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Old 06-18-2008, 10:29 AM
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1.21 giga-watts???!!!!
 
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far better to go with the new heads. Easy 30-40 HP. milling heads might net you 10 HP. Can't remember the exact HP increase per point rise in compression but it aint much.
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Old 06-19-2008, 11:41 PM
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Ditto. You might not even notice the difference just milling the old heads would make, but the RPM heads would give it a serious kick in the pants.
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Old 06-20-2008, 12:40 PM
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If you're getting edelbrock heads, I would spend a little more and get the AFR heads. Better head in my opinion.
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Old 06-20-2008, 04:17 PM
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1.21 giga-watts???!!!!
 
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Edelbrock heads are truly underrated. They make good power for the dough. AFR's are beautiful heads but I doubt you'll notice a lot of difference on the street and you'll save $500 bucks. The heads I would get if I had the dough right now are the Bowtie Vortec 180 cc heads. Or the Edelbrock E-tecs. All of the aftermarket heads are good and on street engine probably within 10 HP of each other. Pick the brand you like.
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Old 06-20-2008, 05:41 PM
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I'm probably gonna get flamed for this (be gentle), but I've decided to keep my existing heads. Just gonna bump the CR and quench up a bit with the 1094 gaskets. Yes, Edelbrock heads would prob give me +30hp or so, but they're also $1,600 over here and the car is quick enough as it is for the street (esp. as it only weighs ~2,400lbs). After talking to the orig. engine builder, if I decide that I need more power, I'll pull the engine (or buy a cut-out) and build it from scratch with a full roller valvetrain, I or H-beam rods, etc.

Thanks for all your advice guys.

Cheers,
Ian.
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Old 06-20-2008, 06:20 PM
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Be carefully before you make up your mind to quickly. If I remember right they are some of the most crack prone heads Chevy ever made. I don't know if I would spend any money on them.

Jordon
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Old 06-20-2008, 06:23 PM
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Quote:
Originally Posted by xxllmm4
Be carefully before you make up your mind to quickly. If I remember right they are some of the most crack prone heads Chevy ever made. I don't know if I would spend any money on them.

Jordon
I'm not spending any money on them (other than just a few $$ to get them milled). If they crack, I'll upgrade.
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