Chevrolet Camaro 1967-2002 - MPG Estimate

I'm lookin for my first car and i have my eye on an '87 IROC and its perfect. The only problem though is it has an aftermarket 4 barrell carb, and im not lookin to race it or anything. Just wanna street car. So its an 87 IROC with a 305-V4 (V4? 4V? i dont know what its called) and i was just wanting to know what kinda gas milage ill be lookin at with this beast? If the gas is gonna be outrageous, how much to put a 2 barrell carb in there? Thanks in advance!

mileage will be better with 4 barrel than with a 2 barrel carb when secondaries are not open, so there is no point in going with a 2 barrel, other than that i don't know

So about what speed will all 4 kick in? or is it different depending on which carb youre workin with? Also, overall, would it be even worth the trouble with this car if i just want to run it as a regular car (no racing)?

It's not about mph to get teh secondaries to kick in, it's gas petal. mash the gas past a certain point, the secondaries kick in.

Gas milage on a carbed 87 Iroc? My guess, 15mpg if you are luckey.

you can get a little better mileage than that, 18 perhaps

you can get a little better mileage than that, 18 perhaps

My main route everyday is has a speed limit of 50 mph so you think the milage would be less than 18 with a 4 barrel?

you might get surprisingly good mileage at 50mph, if it's the car you want, you won't care if the mileage is a little worse than you thought it was going to be, my truck gets 12 :)

It's not about mph to get teh secondaries to kick in, it's gas petal. mash the gas past a certain point, the secondaries kick in.

Gas milage on a carbed 87 Iroc? My guess, 15mpg if you are luckey.

It depends if the carb is vacuum or manual (push of the petal) secondaries... if it is a double pumper holly (manual) then expect pretty bad mileage, if it is a vac. secondary 600 or so holly (vacuum secondaries hardly ever engage... LOL) you might get by with 18... The best i have had out of a carb fuel mileage wise would have to be a good built quadrajet... primaries are very small on a 600 (and keep your foot out of the secondaries of course) I got around 20 MPG in my old 77 nova. I liked my Q-jet, but if you get the right holly they can be great too. I had always had a problem with idling rich on my holly 600 (never could figure it out...)


It all depends on the carb man, all I can say is if it has manual secondaries, keep ur foot out of it if you want good mileage. :cool:

Thanks guys you all are being very helpful. So I wanna see a vacuum carb in this thing if i hope for decent mileage? From the way the guy sounds i highly doubt he would know what kind it is. Is there a big distinction between a manual and vacuum carb so i can see( or have the guy see) what kind it is? Its about 60 miles away so i cant exactly walk up the road and shoot the breeze with the dude.

Thanks guys you all are being very helpful. So I wanna see a vacuum carb in this thing if i hope for decent mileage? From the way the guy sounds i highly doubt he would know what kind it is. Is there a big distinction between a manual and vacuum carb so i can see( or have the guy see) what kind it is? Its about 60 miles away so i cant exactly walk up the road and shoot the breeze with the dude.

If you are tough enough to keep your foot out of the secondaries, then I would suggest a manual secondary carb... (for that extra performance when you need it :cool:) the two get around the same mileage, manuals maybe better... depends on the conditions... lol

I sure did not buy my car for the gas mileage. I had a stock 84 with a 305/4-barrel carb and it got about 15MPH. My current LS1 gets less than that but I have a heavy right foot.

Good luck.

Bill