Engine Brainstorming

[Brambles]

A few years back I had a engine built that I put into my truck but with the intention of later putting it in a car.

I now have the car so the motor is going to get changed a bit for more performance

As it sits now:

360 .030 over
.010/.010 crank
Recond Rods
keith black pistons for magnum heads
Magnum heads, exhausts ported with MP kit and intakes cleaned up
Bronze valve guides
Stock Valves
Chevy Springs/ Seats machined
Stock 1.6 magnum rocker arms
Balance rotating assembaly

Comp ratio is suppose to be roughly 9.4 - 9.5:1
"o" deck height with .040 gasket.

Comp cam extreme energy XE250H
MP dual plane magnum intake
edelbrock 600 cfm carb
1 5/8 flowtech ceramic headers

Need to run 93 with this combo since its in a 4x4 with 31x10.50's and 3.23's

Not sure what the HP level of this motor is but in the heavy truck it hauls pretty good.

I'm going to go over the motor again and finish the intake porting/polishing
Change the cam, new rings, bearings, check everything over because I don't trust the guy who built it. Also maybe install a new single plane intake and different carb.

I'm probably going to run a prepped 904, probably a 2500 - 2800 RPM stall and 3.91 gears in a 1970 Swinger.

What would you figure the best way to get 425 streetable HP out of this motor would be? What changes would you make ie: What cam etc.



Thanks

Brambles

 

[Coyote Jack]

I would think that you would want to get the compression up to about 10.5 to 1. A cam with a total lift of .512 using 1.6 rockers and duration in the 235 range should be enough. You can probably do it with the intake you have if it's an M1 and still retain the bottom end torque, if not, an Air Gap would be the way to go. A carb in the 750 cfm area would help a lot. Maybe a 780 Avenger.

That should get you pretty close.

Jack

 

[Brambles]

How much do you have to mill a magnum head to get 1 point in compression?


The intake is a Dual Plane M1, not sure if it will complement the package or choke it out, I seen some engine build comparo's where the M1Dual plane was decent for torque but the Singles and Performer RPM were much higher in HP.

How are the Demon carbs?

 

[Coyote Jack]

I'm not sure you could get a whole point of compression by shaving the heads. I'm not that technical savvy though.
As far as Demon carb's, I run a 650 Speed Demon. That would have about the same flow as a 720 Holley as they are measured differently. I am very happy with mine. You need a vacumn guage to set them up properly, but once you get it done, they work great.

Jack