383 vs 406
05-05-2009, 05:37 PM
#1
Racer
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383 vs 406
I have a lead on a 350 4 bolt and a 406 2 bolt. I want the hp to be around 425 hp as a starting point for both engines. I know the 406 will probably have more torque than the 383, how much, I don't know. Which engine would you build for street driving?
05-05-2009, 05:57 PM
#2
Le Mans Master
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406 is 6% bigger " than 383. If you start from scratch ... It'll probably cost you a whole lot more than 6% more to build 406 than 383. But in a broad, general sense ... 406 has only 6% more potential than 383.
A good GM 400 block usually brings a lot more $ than a good GM 350 block.
there're many more 350 head gasket thickness/choices than 400 choices.
there're gazillions of 383 pistons; not near so many 406 choices. Typically, the more choices available, the lesser the avg cost is.
400/406 Heads ... steam holes or no steam holes $$$$ ????
350/383 ... N/A.
A good GM 400 block usually brings a lot more $ than a good GM 350 block.
there're many more 350 head gasket thickness/choices than 400 choices.
there're gazillions of 383 pistons; not near so many 406 choices. Typically, the more choices available, the lesser the avg cost is.
400/406 Heads ... steam holes or no steam holes $$$$ ????
350/383 ... N/A.
05-05-2009, 08:32 PM
#5
Race Director
05-05-2009, 09:25 PM
#7
Race Director
Clearancing the block took me a total of 3 hours. I'd do it again in a heartbeat for the extra power it brings. Regardless of a 350 block or 400 block. The small amount of time it takes is well worth the extra torque an HP. I was not in a rush anyway and wanted it correctly done. If anyone building a motor thinks clearancing a block is to much or to hard they should not be building the motor. It really is not hard to do at all.
05-05-2009, 10:33 PM
#8
Drifting
Clearancing the block took me a total of 3 hours. I'd do it again in a heartbeat for the extra power it brings. Regardless of a 350 block or 400 block. The small amount of time it takes is well worth the extra torque an HP. I was not in a rush anyway and wanted it correctly done. If anyone building a motor thinks clearancing a block is to much or to hard they should not be building the motor. It really is not hard to do at all.
05-05-2009, 10:36 PM
#9
Race Director
So would a machine shop charge the same for doing the same machine work to a 400ci block as a 350ci block with the added clearancing ?
05-05-2009, 10:48 PM
#10
Drifting
Most shops would charge to clearance the bottom of the cylinders as we haven't yet as we clearance all the blocks we do incase they ever change there mind later on.
05-06-2009, 04:06 PM
#14
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I've build over a dozen 406's (but for a corvette) and I would go with the 406. But you not only have to be concerned with the steam holes but the distance between cylinders is quite a bit less than with the 350/383 block. In racing we have burned the head gasket between cylinder 5 and 7 when using GM blocks. Currently we have a Dart block with Dart heads and have not hand any issues. I'm just a little leary of the GM blocks it very hard to find a good on these days.
