9formula4

OK don't beat on me for this because it is JUST a question.

Is it possible to put a 4.000" stroke crank into an LT1? Is there anyone that makes a 4.000" stroke crank for an SBC with a 1 pc seal?

Please answer this with respect NO FLAMING or down talk as it is JUST a question.

Thanks guys/gals,

Jeremy

96capricemgr

Only 1 piece rear main 4" stroke I have heard of was a cheap CAT one that would probably work better as a boat anchor than crankshft.

Guys have put 4" stoke 2 piece rear main cranks in using the readily available rear main adapters.

ulakovic22

Never actually put a 4" stroke into an LT1 block before, but I would imagine that clearancing the block would be a lot of work. Probably have to use block fill on the lower part that way when you grind into the water passages it won't leak. Might also have to consider any cam to rod clearance issues as well as piston skirt to crank clearance. I'm sure it can be done, just not sure how expensive it would be.

SS MPSTR

..or how much gain vs. investment/work you'd actually get out of it.

ulakovic22

With common bores you are looking at 402, 408 or 414 cu. in. Piston selection shouldn't be that bad as your compression height would still be around 1.2 depending on your block deck height, standard is 9.2, but they aren't always square so.... I figure it's just going to take a lot of machine work, grinding and a little extra money to buy better aftermarket parts to take advantage of the extra CID.

Edit: Sorry, the zero is missing, it's 9.020 standard and with a 5.7 rod it's a 1.32 CH and since the blocks are rarely square if it is decked a little, you will still be around a 1.2 as stated above. When you get into 1" CH, that's Nascar territory and you won't find much off the shelf.

captaindbol

The 4" stroke can, will and does work. Eagle and others sell a 1pc crank. It's about 30hp better than a 383 along with some healthy torque but only with good heads. This is a very popular combo with the small block fords but they have a much taller deck and the cam isn't in the way. There is no way its worth the time and effort in a sbc especially with the budget parts most guys are running. If you want to run $1200 Oliver rods and a .880 base circle cam then there will be a lot less clearance work to be done. If you need more power than a 383 with GOOD HEADS can put out then its time to step up to a aftermarket block anyway. You also end up with a compression height of 1" since STOCK DECK is theoretically 9.025 not 9.2 as stated above. This has a crowded ring pack, short skirt that has almost no support at bdc. That and there is the lack of material needed to put a dish in the piston. Your looking at ~12-1 compression with a 64cc small block head. Just some observations from someone who has been there and done that. I do this for a living and can not justify the added cost to the customer. If you have a bridgeport mill, buy some decent parts and are willing to risk scrapping a block in the learning process and can do all the work on your own time then it might be worthwhile. You still need some good heads to end up with anything other than a badass truck motor.

11secgen

how about the 3.96 stroke?everybody already makes pistons for that

marshall93z

3.875 for a 396???

rskrause

Listen to the Captain.

Rich

jakesz28

I would just stick to the 383(3.75 stroke) and spend your extra money on a solid roller cam and single plane w/fast ecm.













(Just giving you a hard time.)

11secgen

oh yeah, my bad i was thinking 3.875.