I was thinking 850 seeing as how they came STOCK with 850 q-jets. The 600 holley on it right now seems to really be killing it at high rpms. I'm running an auto....you guys think I should go vacuum secondary or Dp?

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Nice car: 1988 Formula 355, mildly ported/polished Vortec heads, RPM intake, Comp Cams Extreme 268 cam, 650 Holley double pumper, 5-speed/3.73 Richmond gears, and N02 on the way
Old 1/4mile: 13.5@105mph

Evil Car: 78 Pontiac Grand Prix, 500inch caddy motor, edlebrock intake, 600 holley, B@M TH350 tranny, 16inch Iroc-Z rims, blacked out chrome, soon to run 10's...

There's no replacement for displacement!

 

It really depends on rpms and what the engine is going to be used for. If you use the formulas available to determine cfm requirements for an engine, it may be happy with a 750. CID has nothing to do with carb CFM. Prostock cars with 500 CID have 2 1050's. My 383 uses a 850. 358 nascar engines may only use 500 cfm (guessing since I know it's a small number).

Since you're planning on running 10's, an 850 may be perfect or it may be too small. A 1050 may be better suited for the engine.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

 

Here you go.
CFM=CID*RPM*VE/3456

So my engine at max peak HP RPM would be 6500, Performer RPM intake with a VE of (.95 or 95% Volumetric Efficency), and CID of 357CIN.
I need a 638 CFM Carb, hince I needed a carb >= 638CFM.

Hey Stephen broke any roller clutches lately ?
Hey I've put about 200 miles on my TH350 w/B&M ManualPak, and works like a charm, give one a try !!! I also used a hardened steel race, beyond that I keep the units front end play tight.


Ron C. Terry



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'82 Trans Am
'81 Camaro Z-28
'94 Vette LT1 Coupe

 

Gee I wish it was as cheap as a roller clutch. Check the racing forum. I blew up the engine.

The VE of an engine is difficult to determine. Most street engines don't get much above 95% while a race engine can go to 110% or higher. That's why a small race engine can use huge carbs.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas

Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

[This message has been edited by Stephen 87 IROC (edited September 17, 2000).]

 

I'd put a 850 on that caddy.