350 SBC Forged Crankshaft Questions

[Bigprairie1]

Does anyone have any info or experience with GM possibly putting forged crankshafts in any of the truck 350's? Particulary in the era of 1969-1975? To my understanding this would have been due to the heavy duty aspect of 'some' of these motors....but I'm not sure if it is/was just a rumour or whatever.
I know that unless the car engines were High performance (ie: Corvette's and a few others) they got the cast crank.
Again, I'm just talking the small blocks here...particularly the 350's...but also curious a little curious about the 327's and even the 307's?
I'm considering a fun workshop project so I'm wondering what my odds are of scoring a neat rebuildable engine....ideally with a forged crank to get started.
Any info would be appreciated
Many Thanks!!
BP

 

[DECK SWABBER 58]

Re: 350 SBC Forged Crankshaft Questions

I remember the truck small blocks always being more desirable because
they had four bolt main bearing caps versus two bolts on car blocks.
I think the cranks were still cast though unless it was something like
a 302 Z-28 camaro or maybe a corvette.

 

[BuzzStPoint]

Re: 350 SBC Forged Crankshaft Questions

Forged cranks are strong.. Period.
Will beat any cast crank you put in it..

But in my experience, the crank usually didn't cause any problems. usually the bearings and rods caused the engine to go south.

I wouldn't look for an engine with a forged crank. Buy one separate.

Unless you are looking at a 4bolt main. Then look for those. Even then, it's not necessary to get a forged crank. Almost indestructible.. With those engines, the weak point people skimp on is the rods. Or they buy a real cheap master kit and get the crap Japanese/china pistons. When they put a lot of power to it, they blow holes in the pistons.

 

[NSBCraig]

Re: 350 SBC Forged Crankshaft Questions

my 76' blazer had a 4 bolt 350 with a forged crank from the factory.

 

[mnypitboat]

Re: 350 SBC Forged Crankshaft Questions

Some had them, some didnt. I thought, at one time, that all 3/4 ton and bigger early 70s pickups had forged cranks and 4 bolt blocks, but after buying a 72 350 out of a 1 ton Chevy(I pulled it myself) I found out differantly. It was a regular old 2 bolt chevy 350. Nothing special.

 

[howlnmad]

Re: 350 SBC Forged Crankshaft Questions

Stick with the cast crank and go with quality bearings, rods, pistons and rings. The older small block 4 bolt main blocks had a casting number that ended in 0010.

 

[dolluper]

Re: 350 SBC Forged Crankshaft Questions

Here this will help you out a bit
Small Block Chevy Crankshaft Casting Numbers
[Years ][Casting] [CID] [Material ][Journal][ Rmain Seal] [ Applications]
1968-73 1130 307,327 cast large two all
1968-76 1181 350 cast large two all
2680 327 steel small two
2690 350 steel two
1968-69 3279 302 forged large two Z-28
1962-67 4577 327 forged small two -
1968-73 4672 307,327 cast large two -
1975-85 310514 350 - large two -
330550 350 steel two
1975-76 354431 262 cast large two Monza,Nova
1955-67 3727449 265,283 forged small two -
3729449 265 steel two
1962-67 3734627 327 forged small two -
1955-67 3735236 265,283 forged small two -
1957-63 3735263 283 forged small two -
1962-67 3782680 327 forged small two -
3814671 327 steel small two
1955-67 3815822 265,283 forged small two -
1957-65 3835236 283 forged small two -
1956-63 3836266 265,283 forged small two -
1963-67 3849847 283 cast small two -
1964-67 3876764 283 cast small two -
1964-67 3876768 283 cast small two -
3884577 327 steel small two
1967-76 3892690 350 cast large two -
1968-73 3911001 307,327 cast large two -
3911011 307,327 cast large two
3914672 327 steel large two
3923279 302 steel large two
1969-85 3932442 305,350 cast large two in 1979-82 267
1968-73 3941174 307,327 cast large two -
1968-69 3941178 302 forged large two Z-28
1969-85 3941182 350 forged large two Z28, Vette,truck, some nitrided
3941188 350 steel two
1964-67 3949847 283 - small two
3951130 327 steel large two
1970-80 3951529 400 cast XL mns two 3.76" stroke, ext. bal.
1986-on 14088526 305,350 cast large one
1986-on 14088532 350 forged - one truck
1986-on 14088535 305,350 cast large one all
86-88 14088552 350 forged one
///// NOTE/Small or Large is journal size........one or two is rearmain seal

 

[jeeperman]

Re: 350 SBC Forged Crankshaft Questions

In that list,
small or large two = large or small journals, two bolt main caps.
At the bottom is:
"large one"
What is that?

 

[bkwapisz]

Re: 350 SBC Forged Crankshaft Questions

In what I've heard unless you're putting some forced induction or some spray then the forged crank is nice, but not necessary. I'm in the process of building my umpteenth engine and this one will have a large turbo on it, and I DID use a forged crank. Never had one before and never had a problem personally. Maybe it's better to be safe than sorry or maybe I'm just lucky. I guess maybe it depends on the condition of the one you have and what you're going to do with it.

My $0.02 and by no means am I an expert. Good luck with your project.

 

[dolluper]

Re: 350 SBC Forged Crankshaft Questions

large journal ...1 rearmain seal....this site packs everything in no spaces

 

[ezbtr]

Re: 350 SBC Forged Crankshaft Questions

my 76' blazer had a 4 bolt 350 with a forged crank from the factory.

Believe mine did too, boy did it get up and go!

 

[Bigprairie1]

Re: 350 SBC Forged Crankshaft Questions

Here this will help you out a bit
Small Block Chevy Crankshaft Casting Numbers
[Years ][Casting] [CID] [Material ][Journal][ Rmain Seal] [ Applications]
1968-73 1130 307,327 cast large two all
1968-76 1181 350 cast large two all
2680 327 steel small two
2690 350 steel two
1968-69 3279 302 forged large two Z-28
1962-67 4577 327 forged small two -
1968-73 4672 307,327 cast large two -
1975-85 310514 350 - large two -
330550 350 steel two
1975-76 354431 262 cast large two Monza,Nova
1955-67 3727449 265,283 forged small two -
3729449 265 steel two
1962-67 3734627 327 forged small two -
1955-67 3735236 265,283 forged small two -
1957-63 3735263 283 forged small two -
1962-67 3782680 327 forged small two -
3814671 327 steel small two
1955-67 3815822 265,283 forged small two -
1957-65 3835236 283 forged small two -
1956-63 3836266 265,283 forged small two -
1963-67 3849847 283 cast small two -
1964-67 3876764 283 cast small two -
1964-67 3876768 283 cast small two -
3884577 327 steel small two
1967-76 3892690 350 cast large two -
1968-73 3911001 307,327 cast large two -
3911011 307,327 cast large two
3914672 327 steel large two
3923279 302 steel large two
1969-85 3932442 305,350 cast large two in 1979-82 267
1968-73 3941174 307,327 cast large two -
1968-69 3941178 302 forged large two Z-28
1969-85 3941182 350 forged large two Z28, Vette,truck, some nitrided
3941188 350 steel two
1964-67 3949847 283 - small two
3951130 327 steel large two
1970-80 3951529 400 cast XL mns two 3.76" stroke, ext. bal.
1986-on 14088526 305,350 cast large one
1986-on 14088532 350 forged - one truck
1986-on 14088535 305,350 cast large one all
86-88 14088552 350 forged one
///// NOTE/Small or Large is journal size........one or two is rearmain seal

Wow....ok, let me try to figure this out??
Now, is there anyway to find these numbers on the crank with it currently in the engine?
couple of important notes:
-the engine is out of 73' 3/4ton 4x4
-the engine is complete (carb on) and out of the vehicle
...so if any of the above part numbers are on a visible part of the crank I might be able to find it.
Anyone know where I might these numbers?
Thanks Again Guys!!
BP

 

[dolluper]

Re: 350 SBC Forged Crankshaft Questions

With the pan off look for a WIDE parting line running the length of the crank that would be a forged one if it's thin that's cast....as far as the numbers they could be anywhere depending on manufacter and year produced ...a good light and glasses all I can suggest..what are your block numbers it might be a big clue....post them maybe...69-73 truck 307's 3932371 and truck 350's 69-79..3970010 ....there are more let me know I have lots of info

 

[NSBCraig]

Re: 350 SBC Forged Crankshaft Questions

Believe mine did too, boy did it get up and go!

MIne was a rocket even with 38" Ground Hawgs.

Miss my truck.

 

[boomer2]

Re: 350 SBC Forged Crankshaft Questions

In what I've heard unless you're putting some forced induction or some spray then the forged crank is nice, but not necessary. I'm in the process of building my umpteenth engine and this one will have a large turbo on it, and I DID use a forged crank. Never had one before and never had a problem personally. Maybe it's better to be safe than sorry or maybe I'm just lucky. I guess maybe it depends on the condition of the one you have and what you're going to do with it.

My $0.02 and by no means am I an expert. Good luck with your project.

Keep the compression ratio down and use good rods.. ask me how I know.