407 sbc questions

[rocky08]

Need help on how to make power and torque out of this rotating assembly. I have a 400 sbc bored 30 over with a 3.75 stroke crank with 6in rods. The pistons are -16 cc inverted dome pistons that are 11.0 with 58cc heads and 10.3 with 64 cc heads. We have to run cast straight plug heads and a cast non high rise intake as well so limited on things we can do. I am thinking of using the rhs 50 cc with 200 runners ( maybe can angle mill or straight deck to try to boost compression) ? I run a Holley 4barrel carb so I need the intake to allow for that ( I hear that the holley to quadrajet adapter plates actually robs power is that true?) That's all I have for now so any suggestions and part numbers are greatly appreciated. Also we race on a 3/8 high banked track that is heavy most of the times if that helps. Again thanks

[stock car driver]

Need help on how to make power and torque out of this rotating assembly. I have a 400 sbc bored 30 over with a 3.75 stroke crank with 6in rods. The pistons are -16 cc inverted dome pistons that are 11.0 with 58cc heads and 10.3 with 64 cc heads. We have to run cast straight plug heads and a cast non high rise intake as well so limited on things we can do. I am thinking of using the rhs 50 cc with 200 runners ( maybe can angle mill or straight deck to try to boost compression) ? I run a Holley 4barrel carb so I need the intake to allow for that ( I hear that the holley to quadrajet adapter plates actually robs power is that true?) That's all I have for now so any suggestions and part numbers are greatly appreciated. Also we race on a 3/8 high banked track that is heavy most of the times if that helps. Again thanks


Do you have heads already? I would lean towards moving away from the dish piston myself and go for a flat top at least. If you have heads replacing the pistons may be cheaper over all.

fyi thats a 406!!

[hpontap]

What is the engine going in and any special rules you want to follow?
A 200 runner is pretty small for a 400" engine.

[rocky08]

I don't have heads yet all I have is the rotating assembly and block. Anybody ever deal with hvh on on heads and intake being cnc machined and port work? Going in pure stock but around here if you don't have at least 450 true horsepower with about the same torque you might as well stay home. Rules are cast motor -block,heads,intake.

[stock car driver]

I don't have heads yet all I have is the rotating assembly and block. Anybody ever deal with hvh on on heads and intake being cnc machined and port work? Going in pure stock but around here if you don't have at least 450 true horsepower with about the same torque you might as well stay home. Rules are cast motor -block,heads,intake.

For 450 hp with a 4 barrel as you mentioned all you need is a flat top 406 with double humps.

Im making 400 hp with 406s and a 350cfm 2 barrel pinto carb.

Cnc and port work is a easy way to spend money, its not needed.

200cc is the largest runner head I would consider.

[parrot69777]

With a 4 bbl carb and the right cam.....I would use 215's.

[DaveBauerSS6]

I would try to boost compression. Sounds like you got the pistons in the deal, I would cut the deck, thin head gaskets and last resort shave some off the heads. That's cheap HP.

The small 50cc heads are good. I would go with a 200 runner considering the port match issue. Sounds like you can port, but it will be tough to keep the velocity up with that big a transition. I would be careful on the cam choice. Might concider talking to engine builders in the area that build these motors. You did'nt mention what type cam. Looks like a open motor with a very restricted intake.

The intake / carb combo is interesting:

One way is a marine iron manifold with a square Holley. The manifolds can be found in the low rise design. Chevy made iron square intakes for the Hipo 327 in the mid 60's. Harder and more expensive to find, and I'm not sure if you could get more than 650 size on it without mods. Carb can be off the shelf racing otherwise.

The other way is Q jet iron intake and a spread bore type Holley. Manifolds are easy to find and the carb should go to a shop for a racing conversion.

I would not race a motor with a square Holley on a q jet manifold. I don't know of any efficient adapters to do that.

Good luck.

[parrot69777]

If you have to run a cast intake manifold.....and porting is not an issue.....buy a Brzezinski. Best money you ever spent for a cast iron intake.

[stock car driver]

If you have to run a cast intake manifold.....and porting is not an issue.....buy a Brzezinski. Best money you ever spent for a cast iron intake.

Thats awesome because the q jet I modify beat the brezinski I had in back to back on the chassis dyno! and mine is only $250.

The low cast iron intake with a holley pattern is a 2 barrel runner intake with a 4 barrel bolt patternt squeezed on top it flows worse than the q jet intakes and is not a performance piece at all.

The cheap mr gasket adaper from q jet to holley works fine if the q jet has had the plenum all cleaned out of the way.

[hpontap]

You should make 450/450 if you do your homework on the intake side of things. Get with a good cam grinder and he will turn you on to a restricted camshaft. The intake and heads are going to choke the engine once it comes up in rpm's. You should have plenty of mix velocity but it will run out of volume.