As I am now finishing my 455 build, I am looking into carbs, I want to go with the Holley Aluminum Street Avenger but I am not sure if I should go with a 770 or 870



The specs are here:



455 .30 Over with KB Positions

Edelbrock RPM Heads

Edelbrock Performer Intake

CompCams Xtreme Energy Cam Shaft (Don't have the grind on me, but its a aggressive street/strip cam)

 

Need to know that and rear gear as well.

 

Ok so hear we go:

Heads: Stock with a Gasket Match

Pistons - KB icon Forged .30 Over (Running 10:1 Compression)

Cam:

Either the CompCams XE274H or XE284H

Specs of Cams as follows:

XE274H 1800-6000RPM
Peak HP - 447.7HP @ 5000RPM
Avg HP - 120.7HP
Peak Tourque - 561FTlbs @ 2500RPM
Ave Tourque - 185FTlbs

Lift - 0.520" Intake - 0.523" Exh
Duration at 0.050" - 230* Intake - 236* Exh

XE284H 2300-6500RPM
Peak HP - 460HP @ 5000RPM
Avg HP - 121.9HP
Peak Tourque - 540FTlbs @ 2500RPM
Ave Tourque - 182FTlbs

Lift - 0.541" Intake - 0.544" Exh
Duration at 0.050" - 240* Intake - 246* Exh


Which cam would you use, with which carb?

Thanks,

Jim

 

I had the 274H XE cam in my 69' cutlass with 3.73 rear/2400 stall converter, and pretty much the same engine as you except i had ported/polished C heads. I ran the 770 street avenger on mine, was more than enough carb in my opinion, would smoke the tires from 1st all the way through 3rd. The 870 cfm may be ok for the larger cam

 

Those average hp/tq numbers are awfully low.My dyno sheet had avg. tq of 523 ft/lb from 2500 to i think 5700. I'd have to look but I know that was avg tq. and peak tq was 540. Was that from an actual dyno sheet?

 

X2.
But seeing as how you have the Edelbrock heads why not use them and get a cam with duration more like the first but more lift like the second.
I could grind you something like a 232/240 at .050 with .568 lift on both, those heads will take .575 with the stock springs. I did something similar for my buddy's 455 Olds in a 79 T/A, ran sweet.

Jmo.

 

Those were the numberS from CompCams CamQuest I knew they seemed low