I have a 89 iroc Z 5.7 tpi 700 trans,all stock.Were the 350 blocks 2 or 4 bolt mains,and is there anyway to tell with the motor in the car?I cant get to the casting # there's too much in the way.

 

if its stock, 99% sure its a 2 bolt, if you cant get to the numbers, the only way to know is to pull of the oil pan, not a easy thing to do in the car

 

I wouldn't lose sleep over it either way. If it's just for bragging rights, call it a 4 bolt and leave it at that.

 

my 89 iroc had a 4 bolt block in it, but it was rebuilt so i dont know if it was the original motor or not, the only real way to know is to pull it out and check cause even if u have the block number it usually says 2 or 4 bolt on the discription.....y do u ask it doesnt make it more powerful or anythin....

 

"Officially", all iron head L98 motors were two bolt, and alum. head L98 were 4 bolt. I've never seen any documentation showing otherwise.

un"Officially" several people have reported their iron head L98 motor's have had 4 bolt mains. This isn't too surprising actually. It's GM afterall.

 

Yeah, who cares. Its stock. So much other crap will fail around the mains before its ever time to address them. The 4 bolts are just holding the crank in place if **** gets hecktic which it basically will never do witha stock engine. My CK1500 has two bolt main with headers, and exhaust, plust I floor it as much as possible.

 

Just wanted to thank evryone for the info,the reason I was wanting to know ,I'am gonna drop a 383 with a carb in it and a friend of mine wants to buy the motor.I know that a 2 bolt's not gonna hurt anything ,but he's 17 and everything's gotta be a 4 bolt.

 

The simplest way is write down the block numbers and then look on Mortec.com

 

Yup, check the number

 

aparently yall have never used this feature, most of them say 2 or 4 bolt mains.......so even then u still have to pull the pan.....that is the only way to know for sure....

 

Maybe the one that matches up to his block number doesn't say 2 or 4 bolt. I would rather him do a simple check on the numbers vs. pulling an oil pan. If it were my car/engine, I would want to know the numbers regardless.

 

im just stating there is only one way to be sure and that is to pull the pan, if hes gonna build a 383 hell have to pull the pan too, i doubt he has one of the rare blocks that are listed as 4 bolt only.....ive had countless 350 blocks and everytime i run the number it says 2 or 4 bolt mains....i just use the mortec info now to identify the stock cid of a block....its a 2 part process in my opinion, look at number then pull the pan, 1 with out the other is only a half truth....

 

Note to him splayed 4 bolts (aftermarket) are much much stronger than 2 bolt or factory straight 4 bolt caps.

 

My buddy picked me up a 350 motor, I checked the numbers and then pulled the pan to verify. Turned out to be a 4 bolt. He later told me it was out of a Chevy bus.

 

I appreciate all the feedback,what you guys are saying I understand,The 383 I'am building is on a 70's block as a foundation.The motor in the car is gonna get sold,I can't get to the casting #'s with it in the car.I'am just new to the third gen thing.This is my first project thats younger than I am, and plans are already in the works for a whole boatload o mods.