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Old 10-28-2012, 08:27 PM
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Need Head advice for a supercharged build

I have a Chevy 350 in a 1980 Trans Am, I was originally planning on Supercharging it and I have a Weiand 142 supercharger. I'm just wanting to build a mild street car in the 400hp range.

I got the Weiand 142 since it goes on mostly stock engines without a problem. My 350 is a 72 Camaro block, with mostly stock internals. The guy I got it from said it was bored 30 over but I'm not sure about that. Now just a few days ago I found out the heads are off a 305 that was in an 86-92 Camaro. Casting number is 14101081

I'm thinking these would probably be horrible heads to supercharge with. Everyone says 305 heads on a 350 will raise the compression ratio way up.

If these won't work, what would be some decent cheap heads to go with the supercharger? Or could I get away with these heads if I just always run 93 octane and keep the timing in check? I was going to run the MSD ignition retard controller for the timing.

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Old 10-28-2012, 09:57 PM
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You need to find out the actual bore and piston-to deck height measurements so we can calculate your compression ratio. "305" heads aren't all bad either. With stock bottom end i wouldn't run much more than 4lbs of boost though.
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Old 10-28-2012, 11:10 PM
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You will need to get your static compression ratio down into the 8.0:1 to 8.5:1 if you want to take advantage of what a blower has to offer. You'll never get there with small chambers on a 350. An 18 cc dished piston and a 76 cc chamber will yield a SCR of 8.0:1.
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Old 10-28-2012, 11:34 PM
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what would be some decent cheap heads to go with the supercharger?

on a used engine? sounds like you are setting yourself up for a broken engine? Why not rebuild your engine and blue print it with good parts for reliability?aim for 350 horse then add that little blower and have an honest and reliable 470 horse daily driver that has a nice idle,good sound and fair economy if you can resist using all of the power???
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Old 10-30-2012, 03:00 PM
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Start by verifying the actual head casting number. Remove one of the valve covers and look.

To supercharge you want a low engine compression ratio. You want dished pistons and larger chamber heads
76cc. You can buy new aftermarket heads with a lrge chamber or use stock GM large chamber heads.
Avoid the 462624 and all 882 castngs.
Some of the better stock 76cc heads are the 441(x) ,, 487, 920 castings.
Do a google search for SBC head casting numbers.

A moderate duration blower froendly cam allows the blower to make its power
find a cam with 220 to 226 in and 230 to 240ex duration on a wider 112-114LSA.
EG isky cam 201271/281-12
EG:comp cams # 12-404-4
Eg crane cams #113801 or #113821
All these cams make good street power with the 142 blower on a 350..

Here is a new replacement style "S/R " large chamber head.
Dart Iron Eagle S/S Cylinder Heads 10024360A -

Here is a list of some good aluminum heads that wil make big big power
CHEVROLET 5.7L/350 Chevy small block Gen I Cylinder Heads - Assembled Cylinder Head Style - 200cc Intake Runner Volume (cc) - Aluminum Cylinder Head Material - Natural Cylinder Head Finish - 72 Combustion Chamber Volume (cc) - Straight Spark Plug Sty
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Old 10-30-2012, 03:02 PM
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Here is a Brodix IK200 head 70cc bolt on true hi perf head.

A 081 305 head has a small 58ccc ahmber and won;t work well for your purpose.
Compression ratio. too high.

if you are into porting you own heads you can make a decent power full street blower motor head
from a 920 casting or a 441 or 487 casting. should be able to rebuild for $500.
generous porting gets you generous horsepower. Don;t be shy.
Again avoid the crappy 462624 or 882 heads even if offered for free.

All the S/R type cast iron heads are a good new stock head base that gets real good with hand porting too.

You want dished pistons. if the motor has flat tops the cr will be marginally too high
which will limit the boost on pump gas. and power.

change to a -22cc dished 350 piston and large chanber heads for max supercharged boost and power on pump gas.
7.5 to 8:1 cr is best. Its worth it to get the cr right if you want reliable blown power on pump gas.

Here is a nice moderate Lunati street mechanical cam I like to run in this low compression 350 w 142 blower combo
Lunati #401A3LUN Build for a low 7.5;1 cr use a 2.33;1 blower drive ratio .. and a boost referenced 750-850 carb.
easy 490-500+hp with full ported 441 heads or good aftermarket aluminum (200cc port 2.02 valves 70++cc chamber) heads.
EG AFR #1036 75cc eliminators

Last edited by F-BIRD'88; 10-30-2012 at 03:20 PM.
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