What size carb size?

Plug his info into Holley's interactive carb selection program
http://www.holley.com/applications/CarburetorSelector/CarbSelection.asp and what do know, his carb is one of the ones recommended. However, 950's are generally race calibrated which might be part of the "loads up a bunch on the street" problem.

Two suggestions and a comment:
1. Holley 750 vacuum secondary would be much crisper on the street and off the line.
2. Shorter duration cam will lower the ET dramatically. The 60' time is slow IMHO.

Now on to carb size. IF you are racing dynos then bigger is better. Lower restriction in the intake allows better cylinder filling equals more hp. For this reason the cubic inches times rpm over 3456 equation doesn't work for race cars. It will result in a 1.5" depression across the carb. I remember dyno tests where the intake depression or vacuum was measured and the hp kept increasing as they lowered it to 1/2 inchby running larger and larger carbs.

Plain and simple the reason one drives a smaller carb on the street is what happens at part throttle. If you get the primaries too large the carb signal is weak and metering goes to heck. This is the rationale behind the Q-jet and Thermoquad.

It is possible to run a larger carb on the street if you use the right booster to get decent signal. I'd say Holley tech people or a good Holley tuner might be able to help the OP keep the 950HP carb and increase drivability, too. And on the Holley HP carbs the boosters are changeable.

R.

I have no personal experience with the 950 hp but everything i've heard about them has been positive. It's really not that big anyway. It's essentially a 750 mb with radiused entry combined with a 850 bp. Plus, dual plane intakes are more tolerant of big carbs. You may need more initial timing. That cam is pretty hot for a street 400. I would say your problem has more to do with cam, ignition or carb tuning than carb cfm. Are the plugs fouling? You might try leaning out the primaries. I sure wouldn't go changing out the carb just yet. Oh, that cam would probably like more converter than what you have.

Thanks for all the feedback guys. That 12.35 was my best pass in late October at Pittsbirgh Raceway Park year before last with very cool dry temps. Since then I ran a bunch last year and it's run fairly consistently at 12.50 - 12.60 in all temps and air conditions. I thought this was a fair ET given the combo - really not that much displacement and fairly low compression. I need to find out what the comp ratio is given that I'm only guessing? It was also suggested buy some of the guys at PRP that I put another converter in - they thought a Turbo Action Model 38 would wake it up?

Primary focus for the car this year is street so I will try some of the whats been suggested to get it to behave a bit better with the current setup including carb. Should be getting back to the track more later this year and next year so all I was hoping to do I guess was get it into the 11's without a major engine revamp?