Summit racings engine kits, 400 sbc question

[55Willy]

I'm gonna be ordering my rebuild kit through them with thier federal mogul kits. I'm looking at them and I have 2 questions:

1-
why do the kits after 1976 not include pistons (mines a 78-79)

2-
what compression ration would you pick for a 6,000# suburban running 38-40's with a manual. also running hydro brakes so a big cam is not an issue.

 

[55Willy]

motor is a 400 with dart iron eagle heads with 72cc cambers. rollor rockers. gear drive timing kit. 670 truck avenger with a high rise open plane manifold.

 

[4X4HIGH]

Depends on what octane fuel you want to run and also how big the camshaft is going to be. On average though for pump gas and still friendly without detonation keep the CR around 9:1, little higher if you run premium fuel and have a larger cam.

 

[58 apache]

im runnin a 9.78:1 compression have to use premium. buy a balanced assembly.and dont skimp on gaskets. use fel pro performance.i have a 516 525@50 cam with power brakes and an auto lose the holley and get an edelbrock if this is going to be a dd

 

[58 apache]

http://www.youtube.com/watch?v=EAluv_tomys

 

[rjfguitar]

Take this from personal experience....

Go 9.1:1. I have a 406ci with 9.2:1 compression and have to run premium fuel. If I needed to pull a trailer that was any kind of decent weight (4K+) I had to dump in a bottle of octane booster to keep it from pinging. Granted, I live in California and out of state gas is probably better, but not that much.

400's love to ping, their cylinder temps are generally higher due to the lack of water jackets between the pistons, making them more vulnerable to detonation.

I'd give up 5-10HP to be able to not have to worry about detonation, regardless you'll probably need premium anyway.

 

[58 apache]

anything under 93 octane and i have to use an additive. i orig had 54cc combustion heads 10.5:1 i HAD to swap heads to run decent on the street im pushin the limit now with 64cc chambers and 9.78:1....i also had to do ALOT of timing curve adjustment and vac adv adj. before i found an acceptable combo

 

[55Willy]

I'll have to look at the cam card, it's the comp cam 4x4 extreme, 270 ish.

 

[55Willy]

Brand:COMP Cams
Product Line:COMP Cams Xtreme 4x4 Camshafts
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:1,800-6,000 RPM
Intake Duration at 050 inch Lift:226
Exhaust Duration at 050 inch Lift:234
Duration at 050 inch Lift:226 int./234 exh.
Advertised Intake Duration:270
Advertised Exhaust Duration:278
Advertised Duration:270 int./278 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.480 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.498 in.
Valve Lift with Factory Rocker Arm Ratio:0.480 int./0.498 exh.
liftLobe Separation (degrees):111
Intake Valve Lash:0.000 in.
Exhaust Valve Lash:0.000 in.
Computer Controlled Compatible:No
Grind Number:CS X4 270H-11

 

[Chevy305]

lose the holley and get an edelbrock if this is going to be a dd

Sorry, but if you want more power go Holley. Holley carbs have crazy tuneability built into them. It may take some time and pacients to set it up right, but once you do, I promise you it will be worth the effort.

I dd my truck with a Holley and I have no problems at all with it. Nor would I want another carb.

 

[Chevy305]

I like Lunati Voodoo cams the best:

Brand:Lunati
Product Line:Lunati Voodoo Cam and Lifter Kits
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:1,800-6,200 RPM
Intake Duration at 050 inch Lift:227
Exhaust Duration at 050 inch Lift:233
Duration at 050 inch Lift:227 int./233 exh.
Advertised Intake Duration:268
Advertised Exhaust Duration:276
Advertised Duration:268 int./276 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.489 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.504 in.
Valve Lift with Factory Rocker Arm Ratio:0.489 int./0.504 exh.
liftLobe Separation (degrees):110
Intake Valve Lash:0.000 in.
Exhaust Valve Lash:0.000 in.
Computer Controlled Compatible

Cam and Lifters, Hydraulic Flat Tappet, Advertised Duration 268/276, Lift .489/.504, Chevy, Small Block, Kit

• Check to make sure this part fits your application

Take your ride to the next dimension.
Unless you're a witch doctor, choosing the correct cam can be nightmare. These Voodoo cam and lifter kits by Lunati are the answer! The gurus at Lunati have taken cam design to another dimension with profiles never before utilized in cams. Only the world's best profiles are included in this line, making cam selection an easy choice. Voodoo incorporates 30 years of cam design experience with more recent developments in profiles, geometry, and tolerances to deliver the most aggressive ramp profiles ever used in hydraulic flat tappet cams. Asymmetrical lobe designs with slower closing sides set the valve down easy, to reduce noise and premature failure of the valvetrain. These cams deliver more "area under the curve", meaning more throttle response, quicker acceleration, more vacuum, and better efficiency, combined with maximum horsepower and torque. Matching lifters are included.

 

[kwissman]

The Lunati VooDoo cams were designed by Harold Brookshire who used to own Ultradyne cams. They will make a little more power than the Comp extreme series and are easier on the valve train. The Comp extreme are hard on valve train since they close the valve quick.