Square Engine

[JimBobonthefarm]

I've got something I've been kicking around for a while now but not really seriously and thought I'd run it by you.

I've still got the old 305 out of the '85 Chevy Silverado I had back in the early '90's (swapped in a 350). I've been told, fairly recently, that I could rebuild this engine with a 400 crank and create what's known as a "square engine" (not sure what the displacement would be) and that these engines run really good.

Anyone here heard of this or tried it? What's the expected torque/HP if I were to swap it into my '95 Tahoe with the TBI etc.?

[75-K5]

A square engine means the bore and stroke are the same. A 305 has a 3.74" bore and a 400 crank will have a 3.75" stroke. Not completely square but close. A small overbore on a 305 block will make it closer to square.

[joakwin]

a 327 is pretty much a square engine also

427 is another one too

laters

[Diamond Jim]

Square engines, because they usually have a longer stroke tend to produce more torque lower down. Over square engines (more bore than stroke) tend to produce more hp at higher rpms. Under square engines (more stroke than bore) are typically diesel engines found in big trucks, that produce even more torque at very low rpms. (Modern big truck diesels produce there power at less than 2100 rpms, and usually are run at about 1500-1600 rpm highway speed).

Example: When racing on a short circle tracks, where the engine size is about 305 ci and stock size parts have to be used, race teams will use an engine based on the 3.48 inch stroke crank (267/305/350 engines) to get low rpm torque. On longer tracks they use a 3.00 inch stroke crank (265/283/302 engine) to get rpm hp.

If they cant make up their mind, or are confused, I guess they use the 3.10 inch stroke crank (262 engine) or the 3.25 inch stroke crank (307/327 engine).

And that's the truth this early in the morning!

[vic_V8]

the cubes would be 335

[BossHogg 77]

If you used the standard 3.74" bore of the 305, you'd get 330 cu.in. With a .030" overbore, you'd have a 335 - still not as big as the 350 that's (probably) in the Tahoe now. Like the saying goes, there's no replacement for displacement...

[tdrumm]

A 400 crank may not just drop into a 305 block. You might have to machine the crank mains or run oversize bearings. I'm not sure what the main size is on a 305 v. 400 off the top of my head. Also bet on a set of custom rods to make it all work together. Also the 305 might be internally balanced, and the 400 externally. I believe they both use two piece rear main seals. A lot of work for a small cube engine handicapped by the 305's small bores.

[tdrumm]

A 400 crank may not just drop into a 305 block. You might have to machine the crank mains or run oversize bearings. I'm not sure what the main size is on a 305 v. 400 off the top of my head. Bet on a set of custom rods to make it all work together. Also the 305 might be internally balanced, and the 400 externally. I believe they both use two piece rear main seals. A lot of work for a small cube engine handicapped by the 305's small bores.

[chevy6998]

A 400 crank may not just drop into a 305 block. You might have to machine the crank mains or run oversize bearings. I'm not sure what the main size is on a 305 v. 400 off the top of my head. Bet on a set of custom rods to make it all work together. Also the 305 might be internally balanced, and the 400 externally. I believe they both use two piece rear main seals. A lot of work for a small cube engine handicapped by the 305's small bores.

Im pretty sure youd have to machine it the blocks fo a 305 and 350 are the same right!? Anywho its would be the same procedure for a 383 stroker, aka 350 with a 400 crank.

[2nd Time Round]

Im pretty sure youd have to machine it the blocks fo a 305 and 350 are the same right!? Anywho its would be the same procedure for a 383 stroker, aka 350 with a 400 crank.

Yeah the 305 and 350 mains are the same size, 2.45" vs. the 400's 2.65" mains.

[JimBobonthefarm]

Just found this post: Strokin a 305 Questions....

It's hel(l) on a newbie to find something on an established board that hasn't already been thoroughly dealt with.

Thanks for the replies. I was just thinking that motor is in a garage on a stand and could be worked on while I drive and could possibly come close to the 5.3 that's in my dad's truck and runs like a speckled arsed ape.

[02Z]

Just go ahead and drop a 496 in it. That's what the new 8.1 liters are...4.25 bore 4.25 stroke. That would make that Tahoe scream.

[JimBobonthefarm]

Screamers are good.