Oxnard Montalvo

I've been primarily a Chevy man my whole life, mostly small block Corvettes.
I feel that all the manufacturers made some beautiful cars at one time or another, I'd love to own many of them. In other words I'm not **** for any specific brand.
This brings me to my question, and prefaces it so I don't sound like I'm "dissin" Fords.

Any small block Chevy worth it's salt has a forged crank and four bolt mains. I realize the high end Ford motors do, but the run of the mill performance Ford small blocks don't. Why?

dcohen

because the mains werent the weak point in the block

it was the webbing, and even those really arent weak

a standard 302 block will handle 400 + hp with ease

cprstreetmachines

Yep. The blocks split long before a problem with the rotating assembly occirs. Some guys put down as much as 600+ HP on a stock bottom end, and the block goes.

67mustang302

Yeah, forged cranks + 4 bolt mains may have been common in some SBC's, but it's a common misconception that they were necessary for power, it was really overkill on Chevy's part. Regardless of 2 or 4 bolt, most factory blocks have the weak point in the main webbing and not the main itself. The cap and bolts that hold the mains on won't fail, but the whole main will rip off of the webbing if power is excessive or the tune is off. Also, even cast cranks are very strong, and can take more power than the block can, but what kills them is rpm. Cast iron has good compression strength, and the crank is primarily being compressed under power, hence power does kill it. But cast iron has poor tensile strength, and as the rpm increases the centrifugal force stretches the crank, and if it stretches too much it'll come apart. That's also why SFI flywheels aren't cast iron, it's not allowed because under high rpm they can come apart, so they have to be made from either forged aluminum or steel. Typically though high power comes with higher rpm, which is why most people think that cast cranks come apart under high power when it's really the rpm that's breaking it

Oxnard Montalvo

I know this is a strength issue.

I understood the four bolts were to keep the main cap bolts from stretching under RPM which would make it easier to spin a bearing.

Are ford bearings different?

dcohen

you would have to be turning insane rpm to have to worry about that, just use high quality main bolts

67mustang302

Yeah, if your main cap bolts are stretching under power, your bearings are the least of your concern

Colorado_Mustang

The Ford mains are a bit stronger than the Chevy mains. It has to due with the block design. Plus, you're comparing the Chevy's longer stroke to the 302's 3" stroke. That will make quite a difference.