400 421 427?

[sstd595]

I have a new Dart 4.125" bore block and wondering what would be best. Should I run a 3.75", 3.875" or 4" stroke. This is bracket engine so need longevity. This will also be an 18 degree engine. Any help?

[Nosbaby]

any nitrous or power adder's?

[Mike Beck]

I would do the 3.875" stroke unless you want to spray a lot, then go shorter. A 414-421 SBC runs good, especially with 18 degree heads.

[sstd595]

No power adders. in the future it may have procharger, but not for awhile. Have much horsepower you think 13:1 18 degree 421 will make with good heads.

[Mike Beck]

Minimum of 650hp with no problem. Get the combo right, up to 750hp. Think more compression will be needed for a solid 750-800 though. Go post this in the engine section where more people will see this.

[KylePBZ]

421 seems to work out the best from what I've seen. Good balance of power and torque.

[sstd595]

Minimum of 650hp with no problem. Get the combo right, up to 750hp. Think more compression will be needed for a solid 750-800 though. Go post this in the engine section where more people will see this.

I would hope 650, my 23 degree engine 12.8:1 went 10.068 in 3100 lb. (at the time) car. That is about 700 horse I believe. This engine will have lightweight crank and possibly rods also. Mahle pistons most likely.

[z289sec]

We are making 700+ routinely with 13.5 to 1 415,421 combinations with a 23 degree head.

[KylePBZ]

No power adders. in the future it may have procharger, but not for awhile. Have much horsepower you think 13:1 18 degree 421 will make with good heads.


Mine is 13-1, "as cast" AFR 220's, average solid roller, 750 carb, etc.. It's doing about 625 maybe a little better. You should make really good power with the 18* stuff.