Alaska442

How far can a G block 400 be bored?

I just purchased an eagle stoker kit minus the pistons so I need to research this a bit. 455 blocks are getting gone around here but I have 2 G blocks.
A

cutlassefi

You’ll need to have it sonic checked to be sure.
On another note, there’s a million small blocks out there and I have a stroker kit for them, making big block numbers in a smaller, more efficient package. Just saying.

Battenrunner

Not trying to sound mean here, but the 400G block is the most horrible Oldsmobile block to base any build on, unless you want it to appear with correct-numbers and engine for a restoration. If you need to stay with a 400G block for these reasons, have the block sonic-checked for wall thickness, and if it is thick enough, have it bored out as big as you can to find some off the shelf pistons to match the compression height and pin size required to work with an Eagle Stroker kit.

The 400G's small bore (3.87 inch) and the huge 455-sized-stroke of 4.250 inches already makes this a massively under-square engine and it is not known for making good power, no matter what heads you install on it, because cylinder head flow also corresponds with the bore size, meaning you can get more flow out of any head with a larger bore vs/ a smaller bore.

Do you want the engine to have a wide power band or to be a very low-rpm, torque engine for hauling heavy loads?

What is your intended use? Gear Ratio, Transmission?

If you can keep shopping around for a 425, or 455 engine base, you will be much happier, and remember, the Cam and the quality/flow numbers from the heads make a lot more difference than a big stroke on the crank. Either of these engines will easily outpower a stroker kit equipped 400G with a decent set of heads , a good intake (performer RPM)and even a relatively mild cam with 230-235 degrees of duration at .050.

Alaska442

Thanks. I was thinking of how far a g block could be bored To 455 specs if anyone has done this. I guess the casting is to thin.
Maybe sleeve it.