What size carb on a BBC?

otrman · 09-07-2008, 08:42 AM

What size carb should I run on a stock 454 in a 87 3/4 ton Suburban 2wd ? Truck is used for towing.

198787silverado · 09-07-2008, 08:51 AM

i would say a 700 or a 750 edelbrock they are good for a little better fuel efficiency

75K30 · 09-07-2008, 08:51 AM

Which intake are you using? Some intakes will only accept the Holley Square Flange pattern, and other stock intakes may only accept the spread bores of a Quadrajet.
GM has had very god luck with Q-jets, and this might be the way to go for your application.
I am not a big believer in CFM calculators with regards to carb sizing. Too many additional variables come into play.
Gear selection, transmission, tire size, vehicle weight, timing, cam size, vacuum, are all factors in selecting a carb.
Probably want to stay away from double pumpers, with mechanical secondaries and stick with stock relpacement units with vacuum secondaries, or even the old faithful Q-jet.

198787silverado · 09-07-2008, 08:59 AM

yea i agree with 75k quadrajets can b good at times but i jst dnt trust em have had to many problems with them iv heard other peoplep have good luck with them

wild bill · 09-07-2008, 09:30 AM

my 1971 chevelle ,i put a well built quadrajet on it and it was great .put plug's in the primary and secondary jet well plug's to dry it up and a good rebuild ,re bushed the throttle shaft's with thin wall bronze liner's ,it idled perfect .

stumpuller454 · 09-07-2008, 01:39 PM

I`ve had extremly bad luck with quadrajets, only cause they were remand ones, they were very poorly inspected and warped so bad that the throttles would stick or would continuousy flood... went with a edelbrock (which is a q-jet design, but newer) and never looked back, very easy to setup and they run great right out of the box, would say minimum 700cfm, for stock to mild 454, then progress from there...

leolkfrm · 09-07-2008, 09:05 PM

What is or was on it? Min of 750, anything smaller will kill your towing. You will find just as many people like quads as hate them. I've always done my own rebuilds and have great luck with them. Depending on the source of your carb make sure the primaries are sized correctly

09-07-2008, 08:42 AM	#1
otrman Senior Member Join Date: Apr 2006 Posts: 53	What size carb on a BBC? What size carb should I run on a stock 454 in a 87 3/4 ton Suburban 2wd ? Truck is used for towing.

09-07-2008, 01:39 PM	#6
stumpuller454 Senior Member Join Date: Dec 2007 Location: Really FAR NORTH! Posts: 1,031	I`ve had extremly bad luck with quadrajets, only cause they were remand ones, they were very poorly inspected and warped so bad that the throttles would stick or would continuousy flood... went with a edelbrock (which is a q-jet design, but newer) and never looked back, very easy to setup and they run great right out of the box, would say minimum 700cfm, for stock to mild 454, then progress from there... __________________ Red seal certified Journeyman Automotive Mechanic *Supercharger comming soon!*

09-07-2008, 09:05 PM	#7
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 1,456	What is or was on it? Min of 750, anything smaller will kill your towing. You will find just as many people like quads as hate them. I've always done my own rebuilds and have great luck with them. Depending on the source of your carb make sure the primaries are sized correctly __________________ 4 wheels move the body 2 wheels move the soul

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09-07-2008, 08:51 AM	#2
198787silverado Full Member Join Date: Jan 2008 Location: illinoise Posts: 19	i would say a 700 or a 750 edelbrock they are good for a little better fuel efficiency

09-07-2008, 08:51 AM	#3
75K30 Senior Member Join Date: Jul 2006 Posts: 2,630	Which intake are you using? Some intakes will only accept the Holley Square Flange pattern, and other stock intakes may only accept the spread bores of a Quadrajet. GM has had very god luck with Q-jets, and this might be the way to go for your application. I am not a big believer in CFM calculators with regards to carb sizing. Too many additional variables come into play. Gear selection, transmission, tire size, vehicle weight, timing, cam size, vacuum, are all factors in selecting a carb. Probably want to stay away from double pumpers, with mechanical secondaries and stick with stock relpacement units with vacuum secondaries, or even the old faithful Q-jet.

09-07-2008, 08:59 AM	#4
198787silverado Full Member Join Date: Jan 2008 Location: illinoise Posts: 19	yea i agree with 75k quadrajets can b good at times but i jst dnt trust em have had to many problems with them iv heard other peoplep have good luck with them

09-07-2008, 09:30 AM	#5
wild bill Senior Member Join Date: Jul 2008 Location: davenport iowa 52806 Posts: 103	my 1971 chevelle ,i put a well built quadrajet on it and it was great .put plug's in the primary and secondary jet well plug's to dry it up and a good rebuild ,re bushed the throttle shaft's with thin wall bronze liner's ,it idled perfect .