Thread: 350 chev vs. 400 chev

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Originally Posted by racemaster

Reduced base circle cams? By that you mean there are special cams for the 400? I have a retro-fit roller cam for a 350, but if I cant use it then the price of improvement just went up. I have read of cracking problems with the stock heads but I also have some good 350 heads, should I put them on instead? How about you stop beating around the bush?

400's used a 5.565" center-to-center connecting rod, which cleared the camshaft lobes. When you build a 400, you would normally use a 5.7" or 6.000" connecting rod because there are more piston choices with those rods. Problem is, these 5.7" and 6.000" rods will interfere with the lobes of the cam. Aftermarket rod makers, such as Scat, make rods that will clear the cam or you can use a cam with a smaller diameter base circle to clear the rods.

A 400 bored to 406 and with the right cam and a good set of aftermarket aluminum heads will easily make 500 hp. Any head used on a 400 needs to be drilled for steam holes if the motor is to be operated at street rpm's. 400's used for racing would make enough rpm's to keep the steam pockets in the block flushed out without using steam holes in the heads.
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