Pulling vac @ wot on blower motor.
 

Need some help with this one. Got around to hooking up my vac gauge (under the carb) to my blower and found out I am pulling about 1 1/2 inch vac at wot. I have been trying to dial the jetting in and have gotten pretty much there, plugs look good but I am thinking I should see 0 vac at wot. Thinking the carb is under sized. It was an 850 done by Nickerson in Bristol, Pa. It is supposed to be flowing 920/950? I'm thinking I need a 1050. Its a Chevy 496/502 heads 8.5-1
Im getting 5700/5800 with a 24/3 bm and 5200 with a 27/3 bmp. What do you guys think?

Anyone run a quick fuel carb? looking at a 1050.

There is no way you can pull vacuum at WOT if you have boost from the supercharger.

Unless the supercharger belt is off!

He did say "hooking up my vac gauge (under the carb)" so he can pull a vacuum if the carb is too small.
Go here and use the formula to see if the carb big enough, probably not if you are running 5lbs or more in your 502.

http://goodvibesracing.com/Carb_Service.htm

1.5 INCH under the carb is the norm.

Vacuum under the carb on a roots blower is normal. That's why theres all the talk about ''boost referencing" the power valve. You don't need a bigger carb, you need a bigger blower and carb! Then you'll pull that 27p to 5800. :)

Griff, To funny...... If I were checking at the manifold then no I would not see vac. Below the carb/top of the blower yes.Thanks SFO for the heads up. I talked to the guys at Quick Fuel today. They said that what I'm seeing is ok. They think even with a 1050 I might see slight vac. They mentioned if I were in the 3 range then I should be concerned. At that point the carb would be a big restrictor plate. Others say I should see 0 vac. A 920 cfm carb "should be able to feed a 600hp motor" but I was just concerned when I saw the vac being that I never had a blower before........

Not so sure you would get 0 but maybe close like 0.5 but I wouldn't think that is a problem. Couldn't the air cleaner cause this? just a thought

Thanks MT. Maybe next year. Heres a question. I was going to get my 27 worked to try and get a few more rpm. I would like to be at 5400. Do you think that's the way to go or just grab a 26