What's the right carb with my engine setup?

[olds307 and 403]

Street Demon 625 cfm, if you want shiny new. It is a 3 barrel heavily based off the Carter Thermoquad the Carter AFB's replacement, which is the Edelbrock carb. Both carbs will be rich out of box, they are set up for 9+ to 1 350+ ci with bigger than stock cams. One guy put the Street Demon on a 8 to 1 350, got 14 mpg. After leaning it out, 19 mpg. It is very similar to Qjet, 20+ should be no problem with a properly tuned Street Demon. A stock late 70's 305 or 350 Qjet with the right linkage will be very close for your stock 305. I assume that intake is equal to the Performer RPM?

 

[pontiacgp]

Wow, I didn't realize you could get upwards of 25 with a rochester. Maybe I'll have to make the old manifold work and get a pre computer rochester.

I have a 5 speed with a .67 5th gear and 3.08 rear end. I kept it 60 to 65 mph for a 3 hour drive and I got 26.8 mpg.

 

[MrSony]

for a stock 305 a 500 cfm would work fine. A 305 at 6000 rpm needs less than a 500 cfm carb. When we ran in the super stock division we used the GM 602 crate which is a 350 and we were limited to a holley 500 cfm 2 barrel. The chip we had to run was a 6200 rpm and that carb never ran out of gas or power. That holley was a race version but it was only a 500 cfm. That being said I do not like holley carbs for the street. I have a Quadrajet with an adapter to fit my carb on a squarebore vortec intake. With my 355 I can get over 25 mph on the highway.

http://www.carburetion.com/calc.asp

25mph huh? I average 70 myself. 😛 😛

 

[pontiacgp]

25mph huh? I average 70 myself. 😛 😛

70?....you have a quadrajet on a moped?

 

[MrSony]

70?....you have a quadrajet on a moped?

mph.

 

[StreetStock#72]

my 'stock' 87 SS is rated 17/24mpg. I can 'hype-mile'* it to 24.5mpg at 62 mph

* flat ground, A/C off, windows up.

If I was in your (situation) car I'd go with a Holley 0-9895

 

[TURNA]

Wow, I didn't realize you could get upwards of 25 with a rochester. Maybe I'll have to make the old manifold work and get a pre computer rochester.

Dont hold your breath

my 'stock' 87 SS is rated 17/24mpg. I can 'hype-mile'* it to 24.5mpg at 62 mph

* flat ground, A/C off, windows up.

If I was in your (situation) car I'd go with a Holley 0-9895

Wont work with his intake

 

[slowestmonte]

After hearing about the MPG numbers you guys are getting, I think I may go back to the old CCC carb, I'll just have to get all new sensors and rebuild it, and I'll have to put the old manifold and distributor back on. Good thing I didn't cut any wires.

 

[pontiacgp]

mph.

what are your revs at 70mph

 

[MrSony]

what are your revs at 70mph

It was a joke man. You put 25mph instead of mpg.