Lt4 crankshaft

[MPax]

I purchased a lt1, supposedly from an Impala ss, from craigslist. When I tore it down, I noticed that the crank has the lt4 rolled fillet. Was this common in ss impalas or did I just get lucky and maybe they ran out of standard shafts that day? Could that have been supercharged? Any thoughts appreciated!

[SSlowBoat]

I purchased a lt1, supposedly from an Impala ss, from craigslist. When I tore it down, I noticed that the crank has the lt4 rolled fillet. Was this common in ss impalas or did I just get lucky and maybe they ran out of standard shafts that day? Could that have been supercharged? Any thoughts appreciated!

Wat? Post a picture of said special fillet, I have numerous stock cranks laying around I'd like to compare it to

[MPax]

@TubbyFormy here you go. I'm including a pic of an old gen 1 crank for reference. I got to thinking today, I wonder if I was right about this crank. After closer look at the two, I think I am. What do ya'll think?

Gen 2 crank(lt4?) Notice the rounded corner where the bearing surface transitions to counterweight


Gen 1, notice the more abrupt ending at corner

[MPax]

P.s. you need to zoom in! Lol

[SSlowBoat]

Gen 2 lt1 stock crank. I'm not seeing much of a difference or what is making a "lt4" crank special. Looks the same as your "lt4" crank. Someone correct me if I'm wrong, but lt4 ' s just had 4 bolt mains

[firebird_1995]

You would need a fillet gage in order to measure that small of a difference. I can't see much of a difference either. You might try taking a flashlight and shining it against the fillet area, then take a picture of the shadow. Then you can compare the two and see if there's a difference

[MPax]

You are right, they do look alike. Up close in person there is a definite difference in the two I have, so I may have got to excited and jumped the gun. 4 bolts, yes. Also, they were made from a stronger, special nodular iron blend. My source on that is from Myron Cottrell's "how to build max performance Chevy lt1/Lt4 engines". It shows a picture of the two cranks side by side, but it's hard to distinguish. Thanx for your response.

[SSlowBoat]

You are right, they do look alike. Up close in person there is a definite difference in the two I have, so I may have got to excited and jumped the gun. 4 bolts, yes. Also, they were made from a stronger, special nodular iron blend. My source on that is from Myron Cottrell's "how to build max performance Chevy lt1/Lt4 engines". It shows a picture of the two cranks side by side, but it's hard to distinguish. Thanx for your response.

Ah I forgot that book, I have yet to purchase

[MPax]

It's a good book, I've learned a lot! Only flaw is that pic I'm talking about, hahaha!

[popo8]

Ah I forgot that book, I have yet to purchase

Have it on my shopping cart on ebat. 19 bucks.