Visit The Dirt Forum for More Information

Author Topic:   400 4bolt main
Dirt Full Roller

Total posts: 31
posted March 12, 2001 12:51 PM
I was wondering what people thought about using a 400 4bolt main. Its the only 400 i have and do you think i should maybe build a 377 from it, maybe buy using the 350 crank in it, it will relieve some pressure on the main caps and webing. or should i just build a 355. I am running an emod. thanks

Dirt Freak

Total posts: 219
posted March 16, 2001 02:57 AM
I'm not sure why you would build a 377 ? I have built several 377's over the years and would say they are a great motor, but a 377 will still pound the bottom of a 400 block out just as easy.........I think easier in the old days when you had to run a spacer bearing........with the full bearing now you have a little better deal. But with a spacer bearing the crank could realy get to whipping around in the block.
The biggest thing to break the bottom of the 400 block is compression.......a 350 crank is a little lighter, but not enough to save anything......compression is your friend in making power, but it's the same power that will break the webbing in the mains..............
Stock 400 block with stock caps live forever at 11.5 to 1 they also live a season or two at 12 to 1 if you go over that you NEED a 2 bolt block with splayed caps in my 15 years I've broke 2 stock forged cranks that were each 9-10 years old. We ran these motors 20 shows a season. I've broke 3 main caps in 377's.
Another thing to look at in a 377 is the parting line of the caps when you take the motor will see little lines where the cap is dancing around if you use the spacer bearings.........the caps that broke were all old stock caps.....we didn't lose anything when they broke. I found them when doing a freshen and we took the motor apart and installed after market caps.......
This has been what we have done in the past and why, I hope this helps you in some way........

Back to the Archives