434 SBC Build

[J Poissant]

Hello guys that know things about 400 stroker motors. I’m considering building a 434 Small block to replace the 425hp 360 sbc in my Camaro.
Goal is 520-550 hp and 6800-7000 capable.

HP for fun and the extra rpm to work well with my gearing on the typical autocross and longer tracks I run it on.

First questions:
I’ll be using a OE 400 block (have access to one that is virgin/ unbored). What clearancing is needed in the oil pan rail area for a 4” stroke? Special pan needed?

[srode]

I can't tell you much about the pan, but the GM block I have in my convertible was modified to build up to a 434 and there was relief work done the block to make room for the longer throw or counter weights (don't remember which). Are you planning on a aftermarket block or a GM 400? Also you may need to check for clearance on your cam lobes, might need to use a small base circle cam to make it work.

That said, you can get your HP goal with a 400 build I think. The one I built is 450 hp and 500ftlbs of torque and has a pretty flat torque curve. It's not a radical build at all, 10:1 compression and a mildly lopy cam. The 434 would be a great high torque platform, not so sure it would be a good choice for the RPM range you want.

[c3rocket]

I have a 434 dart block scat crank and rods afr heads runs good 652 hp I autocross with it all the time .

[Y-TRY]

FWIW - There are easier ways to make the power you’re looking for. You’re going to need 6” or longer rods, especially with a stock block. The cam will need small base circle to clear said rods, so you’ll need a good billet cam. That much stroke also requires pistons with shorter skirts so they’ll be rocking more. You’re going to make power but you’ll probably window the block at 7k.

It’s awesome you have that block but it’s going to be the weak link. IMHO a 377, with 6” rods, would be a great high rpm combo for that block, with less side-load on the cylinders and standard base circle cam. You have enough room to make it sturdy and stable enough for high winding. Like a DZ302 on steroids.

[c3rocket]

I like the idea of a 377 but to make over 500 hp would be a little radical .