[performerrpm]

i dont know much about the earlier blocks, i googled some builds but alot of those threads went off topic.


can a 400 crank be machined down to fit the small journal? can they be bored to a 4.151 bore? theres one listed on market place near me but wasnt sure if its something i shoukd mess with.

this would just be something i threw my unwanted 400 parts at that i would like to see combined as a long block

with a good set of heads it seams like there could be some decent power made. dunno how competive it would be against other builds, i did read they are tough block

[tom s]

Might not be worth the effort,I think 55-58 take a diff bell and flywheel.Not sure about motor mounts.Jack might know more.Tom

[b-man]

No side mounts until 1959 389.

Bellhousing adapter needed for any modern automatic trans and slim pickings for manual bellhousings and flywheels.

Starter mounts to the bellhousing.

By the time you modify a 400 crank to fit you would probably have enough invested in it to just buy a 400 stroker crank and put it in a decent 400 block.

Seriously a pain, not an inexpensive endeavor.

Just build on a good later 400 block and leave that 370, even if you got it for free it’s still no bargain.

[Gary H]

One of the problems with the 370 engine is main bearing quality and availability. I actually have a 370 block and crank I'd sell. Looks to be a forged crank.

[performerrpm]

i thought it might be one of them great ideas i get thats actually not lol.... i guess ill let someone with a 50s pontiac snag it up

[694.1]

I have also wondered if a modern steel crank could be turned down to fit a 55/56 or 57/58 block.
Intriguing.

[b-man]

Originally Posted by 694.1

I have also wondered if a modern steel crank could be turned down to fit a 55/56 or 57/58 block.
Intriguing.

I’m sure it’s not beyond the capabilities of any good crankshaft shop, so long as the oil passage drillings in the mains don’t end up too far off center after turning them down.

But as already stated main bearings that are decent are few and far between, and turning down all the mains on a crank is costly too.

[Jack Gifford]

For those who might want the "tough" '58 block and only want a "400 size" engine, why not simply build a 382 c.i. like what I built for my '59 GMC (stock 3.62" stroke, 4.127" bore)? Not far from 400, with the advantage of a forged crank. Sorry, no dyno numbers... wish I could take you for a ride in the 3,900 pound truck though!
performerrpm: Most '58 blocks will bore to 4.151". The wall thickness of my particular block had some worrisome spots so I quit at 4.127".

[blueghoast]

I've got one that's bored and stroked to 428 ci.
It's in my 57 4-door right now, I'd be willing to let it go.

GT

[steve25]

There are plenty of other easier and cheaper ways to gain the high rpm Hp improvements of running a main bearing size that the 370 had..

[Bill Eveland]

There are transmission adapter kits available, Wilcap and Bendtsen, but 55-60 blocks are on their own for bolt pattern.