im only gettin 8-12 mpg city. its terrible and i dont know why. my engine is nothin really spectacular.

heres what i got
1967 camaro ss. 350, th - 350 tranny. 2.02 heads, bored .030, holley 600 cfm carb, weiand intake(dual plane). uhhh 3.08 gears, no posi, no conveter.

i figured i should be aorund 15 mpg. im puttin in 3.73's and a eaton posi this friday. and then if im not getting any wheelspin at the track im puttin in a 10" 2800 conveter. i know itll kill my mpg a lil more. but im aimin for low 13's.

what can i do to get better gas milage. oh yeah i got a #70 jet in my carb. i know its a bit big. but i ran 2 tenths faster with a 70 than a 65. and it runs a lil better.

 

Well, the fact that your mileage sucks, and you were having cooling issues before, leads me to ask:

What are your initial and total timing numbers?
What octane gas are you running?

The gears should help out, but I wouldn't expect anything better than around 15 around town with a carb, depending on your driving habits.

 

Some cam specs may help.

 

8-12 mpg from a Holley isn't too bad. If gas mileage is that important, might I suggest a Q-jet?

 

how much would the q-jet hurt my performance tho? i run 91 octane, if i run 87 or 89 it detonanates on me when it gets hot. no problems with 91 yet.

 

Your mileage will be best with vacuum advance cannister hooked up to full time vacuum.

 

I hate Holleys... plain and simple. I've never heard of any problems with performance on well built small block and a 750-cfm Q-jet. The best part is just like the Ronco Cooker... "you set it, and forget it!"

Try that with a Holley.

 

properly tunes, a Q-jet won't hurt performance on a street car at all. I know of several guys on another board with pretty strong SB's running 12's and lower who won't run anything but a q-jet.

 

Jet builds some pretty nice Quadrajets. You can get them through summit or jegs. I wish I had spent the money to have gotten one when I was buying instead of the Edeltrash carb I'm running now, but I was hoping to have sold the car by now too.

 

Ok, I want to hear more... I was about to buy an Edlebrock Q-jet. Are they that bad?

Up until now, I've always just bought OEM rebuilt replacements for my street cars. If I needed anything trick, I'd just have them rebuilt professionally.

As for performance, a lot of people prefer Q-jets over Holleys because they're more reliable and are more consistant. Isn't that what you want for racing?

 

depends if you're going bracket or heads-up

Holleys aren't ALL bad, though. They do seem to have more things that can be more easily adjusted - the really fine-tune stuff like air bleeds and such. Might help a pro-level bracket team with good data logging be able to tune the car to a great variety of weather conditions quickly.
Of course, so many adjustments probably contribute to them falling OUT of tune more often...
Holleys also have a slight benefit for all-out WOT performance. Having 4 equal barrels theoretically leads to better fuel distribution, especially on a single-plane, or tunnel-ram. The Q-jet with small primaries and large secondaries would in theory tend to put more fuel to the rear cylinders. Of course, most of the time you're only on the primaries where you get the benefit of finer throttle response and better fuel economy that the small primary bores give.

Plus, a Q-jet just adds to the 'sleeper' look!

 

I was referring to Edeltrash's AFB style carbs. I you have a daily driver that you don't care about performance, this is the carb for you. For some reason the electric choke won't work on start up when it's cold. It works well after I've driven about 100 yards. Then it won't shut off until the engine gets up near 180*. So it keeps my idle high when I don't need it high.

I've never ran their quadrajets, but why would you pay $50- 100 more for an Edelbrock Q-jet (calibrated to OEM specs) over a Jet built Q-jet that you can get in 3 stages of performance?

 

Because I'm running a completely stock 327. I looked at the Jet built Q-jets, but they're probably more carb than I need.

 

Just get a stage 1.

 

nah, no such thing - you just don't have enough engine!