Thread: Vortec heads

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I have a short block 400 sbc. I was thinking of using a set of vortec heads (906). Some say OK others told me the 906 heads would raise my compression to much. This is only for the street. I do wish to use pump fuel and have dependability when driving my classic. The stock 400 is only 150 horses. I would like a little more. Like I said this is a short block still on the skid. I have no intention of changing cams.
Thanks for your feed back
phil

I'd estimate the static compression ratio of a 400 with stock pistons and 906 heads at 10.8:1, too high for cast iron heads and pump gas. 76 cc heads would make a 9.6:1 SCR and would work better with pump gas. If you are planning a street motor, drill the heads for steam holes like the factory did.....
http://www.gregsengine.com/convertin...ds-to-400.html


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Thank you!

OK. Option 2. The Engine in my 1974 Avanti 2 is an SBC350 with casting code CJJ. I was given the 400 short block because the 350 was a little tired. The 350 (CJJ) codes out to be made in 1971 with 270 hp, a 4 barrel carb and standard trans. It has 441 heads.
If I freshen up this engine should I use the 441 heads or my 906 Vortec heads? Again I wish to use pump gas.
Thanks to all.

I don't have the numbers, but quite sure the 441's will outflow and outperform the 906's.... What are the valve sizes in the 441's? There's some really sharp SBC guys (I'm not one) on here, I'm sure they can give you some good advice on how to get a bit more out of them without wrapping up a bunch of $$$$$ in them!!!!

Pictures of the Avanti, PLEASE!!!!!!!!!

Originally Posted by Dave Severson

I don't have the numbers, but quite sure the 441's will outflow and outperform the 906's.... What are the valve sizes in the 441's? There's some really sharp SBC guys (I'm not one) on here, I'm sure they can give you some good advice on how to get a bit more out of them without wrapping up a bunch of $$$$$ in them!!!!

Pictures of the Avanti, PLEASE!!!!!!!!!

Hey Dave,
Thanks for your reply. Here are a couple of pics, I hope. I'm new here and not sure how things work.

Things work just like you thought they did! Cool Car! Thanks for the pics and good to see you here...

Originally Posted by Dave Severson

I don't have the numbers, but quite sure the 441's will outflow and outperform the 906's.... What are the valve sizes in the 441's? There's some really sharp SBC guys (I'm not one) on here, I'm sure they can give you some good advice on how to get a bit more out of them without wrapping up a bunch of $$$$$ in them!!!!

Pictures of the Avanti, PLEASE!!!!!!!!!

Hey Dave,
Thanks for your reply. Here are a couple of pics, I hope. I'm new here and not sure how things work.

This link may help.
Tech - 441 sb chevy heads
That Avante is awesome!

Originally Posted by Dave Severson

I don't have the numbers, but quite sure the 441's will outflow and outperform the 906's....

Ummmm, not quite Dave. The L31 heads are the best flowing production cast iron heads that Chevrolet Motor Div ever produced. The 441's don't even come close. Here's a decent tutorial.....
http://www.crankshaftcoalition.com/w..._cylinder_head
I've been told that the runners were patterned after the aluminum LT1 heads, but cast in iron instead of aluminum.

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