factory 400 block

[pl235c]

How much power can a factory 4 bolt main 400 block handle? looking to make 400 -450 hp and well over 500 lb ft of tq.

 

[StreetBu]

You'll be fine at that power level.

 

[grizwald]

i'm pretty much there now with what i've got and plan to get more out of it.

 

[84ta406]

At that power level you're fine. The factory 4 bolts were actually weaker than the 2 bolt main castings. I wouldnt try to push too much more unless you have a girdle in the lifter valley and possibly the mains as well. I'm sure theres more in the motor but you dont want to be sitting there with a ticking time bomb. What RPM do you plan to spin to?

 

[pl235c]

no higher than 6k

 

[lilbowtie]

After 3 years @520hp I developed a crack @ the bottom of #2 cyl. Going back together with a 2 bolt and hard block.

 

[grizwald]

After 3 years @520hp I developed a crack @ the bottom of #2 cyl. Going back together with a 2 bolt and hard block.

so your current block is 4 bolt main?

for the record, mine's a 2 bolt.

 

[84ta406]

Mines a 2 bolt as well and has seen 7000rpm a few times on the stock bottom end too! lol I dont recommend it either though.

The 4 bolts start to crack around the mains because theres not enough webbing around that area.

 

[grizwald]

i'm not as concerned about the bottom end as i am the fact that i have a hydraulic cam and stamped rockers with press-in studs. 6000 rpm even worries me a bit!

 

[84ta406]

Yeah that would worry me as well. Luckily I have a Hyd. roller with pro magnum rockers and 7/16" studs.