Question about steel crankshafts

[Demonracer]

I acquired a SBM steel crankshaft & I was wondering how to tell the difference between a 340 shaft & a 360 shaft. Does anyone have a quick way to tell the difference?

 

[JBurch]

Well first of all a 360 crank is not gonna be steel, the main bearing journals of a 360 measure 2.81 inches, a 340 measure 2.50 inches.

 

[RustyRatRod]

Somehow, I don't think post#2 did it for you, so here is how you tell the difference.

 

[krazykuda]

360 has larger main bearing journals...

 

[Bodyperson]

Though the info here is correct...that aint a "340" steel crank

 

[RustyRatRod]

It's correct. At least it's as correct as you're gonna get for free.

 

[Bodyperson]

it's correct. At least it's as correct as you're gonna get for free.

lol

 

[pishta]

steel crank sings when struck, cast sort of doesnt. Now thats alot of help, eh? parting marks are a dead giveaway as the wide ones are steel, as well as the corners of the throws, hard corner is cast, rounded corner is forged. Well, here is another freebie: 340 cast (hard throw edges too) and a 340 forged (soft throw edges, wide part line)

 

[Bodyperson]

And large holes drilled in 'em to offset the weight of the 340's heavier connecting rods.

 

[Marcohotrod]

And large holes drilled in 'em to offset the weight of the 340's heavier connecting rods.

not, 340 and 360 and some 318s rods all weighed the same at around 725 grams. the 340s did have a heavier piston.