302 blocks cracking in half?

[bullitt boy]

Was talking to a guy driving a Vette last night . He was telling me about the 302 blocks being two piece or something and that they had a habit of cracking in half.anyone ever hear of this?

 

[94tbird]

this is not 2005 tech, moved to chit chat. And If he was referring to the old 5.0 blocks then yes they were prone to cracking with upwards of 500hp

 

[1FastS197]

bound to be talking about the old pushrod motors... and yes the 347 strokers would crack in half... 331 mostly held good...

 

[spedly]

bound to be talking about the old pushrod motors... and yes the 347 strokers would crack in half... 331 mostly held good...

No no the 347 burned oil. They all cracked in half. If your going to do more then bolt-ons you need a dart block

 

[19COBRA93]

It doesn't matter if they're strokers, or which stroker, or stock stroke... Some of them didn't seem to like anything over 500 hp. Others lasted. It's really no different than what the 3V stock shortblock guys go through. Some hold, some don't. Except instead of rods snapping and destroying everything, it's the block that literally splits right down the center.

I personally cracked a main on a single turbo setup making just over 520 rwh, but on another stock block I made way over 600 rwh and ran mid 10's with no problems.

Just like the 3V's, it's a combination of RPM, and HP that decides when they let go. I kept the rev's down on my turbo car (93 cobra), and I'm sure that helped it live under a lot of hp (622rwh, 734rwt -stock block).

 

[Bingo]

It doesn't matter if they're strokers, or which stroker, or stock stroke... Some of them didn't seem to like anything over 500 hp. Others lasted. It's really no different than what the 3V stock shortblock guys go through. Some hold, some don't. Except instead of rods snapping and destroying everything, it's the block that literally splits right down the center.

I personally cracked a main on a single turbo setup making just over 520 rwh, but on another stock block I made way over 600 rwh and ran mid 10's with no problems.

Just like the 3V's, it's a combination of RPM, and HP that decides when they let go. I kept the rev's down on my turbo car (93 cobra), and I'm sure that helped it live under a lot of hp (622rwh, 734rwt -stock block).

I've never heard of a block failure on an S197 (unless you consider a rod making a hole in the block a 'block failure').

 

[US-1]

I personally cracked a main on a single turbo setup making just over 520 rwh, but on another stock block I made way over 600 rwh and ran mid 10's with no problems.

I can't tell you how many of them we've split with N/A combinations. I know we put three of them in Suzanne Towe's car during the '07 season. Low 11 second N/A setup with a C4.

I broke two of them back to back in my Fairmont. Literally. Fourth run on the first one, took it out, built a new one, broke it on the first run out of the trailer. Said screw it and put the Cleveland in the car.

 

[1FastS197]

It doesn't matter if they're strokers, or which stroker, or stock stroke... Some of them didn't seem to like anything over 500 hp. Others lasted. It's really no different than what the 3V stock shortblock guys go through. Some hold, some don't. Except instead of rods snapping and destroying everything, it's the block that literally splits right down the center.

I personally cracked a main on a single turbo setup making just over 520 rwh, but on another stock block I made way over 600 rwh and ran mid 10's with no problems.

Just like the 3V's, it's a combination of RPM, and HP that decides when they let go. I kept the rev's down on my turbo car (93 cobra), and I'm sure that helped it live under a lot of hp (622rwh, 734rwt -stock block).

my machinest said that the 347 was a little to much bore for the block and the pistons would want to push outward more... this put pressure on the center of the block... and inturn splitting one straight down the middle... but i have never got a 302 to make anywhere near 500hp... pretty sure it would have the same affect... me personally, i have never split one but i have seen them first hand and help remove the carnage... it was a 347 and that was what our machinest said he thought... they do split right down the center... Boss block is the way to go... actually i retract that... a windsor based motor is the way to go but thats just my opinion...

 

[19COBRA93]

I've never heard of a block failure on an S197 (unless you consider a rod making a hole in the block a 'block failure').

I wasn't referring to block failure on the S197, I was referring to rod failure happening at roughly the same hp level as the blocks splitting on the old 302 blocks.

I can't tell you how many of them we've split with N/A combinations. I know we put three of them in Suzanne Towe's car during the '07 season. Low 11 second N/A setup with a C4.

I'll bet your were spinning them way past 6000.

my machinest said that the 347 was a little to much bore for the block and the pistons would want to push outward more... this put pressure on the center of the block... and inturn splitting one straight down the middle... but i have never got a 302 to make anywhere near 500hp... pretty sure it would have the same affect... me personally, i have never split one but i have seen them first hand and help remove the carnage... it was a 347 and that was what our machinest said he thought... they do split right down the center... Boss block is the way to go... actually i retract that... a windsor based motor is the way to go but thats just my opinion...

Piston bore makes no difference. FWIW, a 347, 331, and 306 all have the same 4.030 bore size. My turbo car was a .040 over stock 302. The rod length on the strokers could contribute I'd imagine, but the cracks/splits start at the mains (crank), not the top of the motor. They basically split from the bottom up (or center like you mentioned).

Anyway, there's no question the stock 302 blocks are crap. It's a gamble anytime you start really pushing one. Definitely the 4 bolt blocks are a great upgrade. And, FWIW, the 351's will do the same thing, just at a higher level.

 

[1FastS197]

Piston bore makes no difference. FWIW, a 347, 331, and 306 all have the same 4.030 bore size. My turbo car was a .040 over stock 302. The rod length on the strokers could contribute I'd imagine, but the cracks/splits start at the mains (crank), not the top of the motor. They basically split from the bottom up (or center like you mentioned).

Anyway, there's no question the stock 302 blocks are crap. It's a gamble anytime you start really pushing one. Definitely the 4 bolt blocks are a great upgrade. And, FWIW, the 351's will do the same thing, just at a higher level.

oh yeah man... thats what i was try'n to say on the rod length... he said when you add the extra length of the rod and bore size of the piston it wants to push out... sorry, i suck at try'n to explain whats rolling around upstairs...

 

[US-1]

I'll bet your were spinning them way past 6000.

Why hell yeah.


I also spun the Clevelands up there too. We'd go 8600 rpm usually. Never screwed up a block on those things though.