drove the car home from Atlanta dragway, which is about a 180mile drive. got stuck in alittle traffic for about 30mins and stopped through macon on the way home to hangout with some friends so there was alittle bit of on and off during that trip. i also "played" alittle when i was in traffic and in town. got 20.5mpg

so i decided that i'd do my best this week to get good mileage. normally i can go about 3.5-4 days between fillups, which is about 180miles. (this is around town and highway mixed). so far i've gone 150miles and am JUST under a 1/2 a tank. this car is NO slouch either, which is why i'm so pleased.

worked over 750 double pumper
holley street dominator intake
worked 113 casting aluminum vette heads
crane solid cam 238*/248*@.050 .480"/.500"
comp Pro-magnum 1.5 roller rockers
hedman longtubes and 2.5" true duals
10.2:1 c/r
700r4 w/ lockup, but has a 10" 4000stall ATI converter
3.73's with 275/60/15 m/t ET Street Radials.

just thought i'd share my findings. i hope that with the upcoming road trips i have planned that i can net close to 23-25mpg on the highway given i don't get caught in too much traffic and don't make too many stops.

 

750cfm double pumper, solid cam, 3.73 gears and 20MPG? low 12sec ET, and low budget car.

So now you're setting mileage records to go with your incredible ets? Sooner or later you're going to get audited by the hotrod police

You should write a book.

 

Damn im hoping to get 18

 

 

i get like 12... on a good day... and if i even think about getting on it.... the gas gauge drops like a stop watch

 

I shouldn't comment here I get about 9mpg highway :-/ and i have lot smaller setup. I can get my carb setup right gerrrrr.

 

ok, update*

i got to 180miles on the tank and rolled by a gas station that was $.25 cheaper than anywhere else in the area, so i had to fill up and check the mileage. 15.99mpg, this is mixed driving city and highway. i'd still like to go on another road trip to see what kind of straight highway mileage i get cause i know i'd get around 23mpg.
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this is definitely still the case though when i get into the secondary side of the carb when i really want to lay into it. i can feel the secondaries under my foot when i stomp on it and i watch the tach go up, and the gas go down.

 

Single-tank calculations are rarely accurate, especially when the mileage is short. On my roadtrip in February, I had fill-ups with 27 mpg and 13 mpg. For the entire 1000-mile trip, it came out to 22 mpg.

 

 

you all suck(jk)

i get 5 mpg around town. i never tryied highway driving. i would imagine somewhere around 7mpg

 

7 mpg is pretty bad.

There was a guy locally here who bought a 1970 big block Corvette and decided he was going to drive it cross country. He averaged about 9 mpg, and by the time he got back he'd paid more in fuel than he had for the car originally.

 

wish i was getting that with my lt1. 17 no matter what i do. must be my tune. lol

 

i think that the bad gas mileage is do in part to the 950

 

That's really amazing, given your cam and gearing. I think the lockup converter is helping you tremendously, especially versus running a non-lockup 4000 stall unit!

Holleys can give good mileage, properly tuned and driven easy, but I doubt I could equal your results.

 

hmmm....i guess i just have the magical touch or something? lol!

 

actually one of the Mags i read... slips my mind but i seem to remember chevy hiperformance did an article on EFI MPG and throttle response with a carb...

all you need is time, patience, tools and parts( jets, air bleeds, etc ) and a $600 tuning software( wideband o2 and the such) lol and a laptop.... but it can be achieved

 

I'm so jealous. My bone stock LG4 and 2.73's don't get that.

And I think you're prolly 8 seconds faster than me in the 1/4

 

Didn't the L03 in your Stro get close to that in MPG, but like 10 seconds slower in the 1/4? JK.

BTW, mw66nova this shows that you have really spent the time to dial in your setup. Now if it only had EFI and you put the same effort into tuning it.

 

EFI would be cool, but the initial cost is why i haven't justified doing that yet.

 

wow.. i burnt 1/8 of a tank in 15 minutes on the highway today doing the speed limit. i'm guessing between 6 and 8 MPG... first time the car has been out since July tho... I'm thinking i need to tune the carb a bit better.. lol

 

Don't overlook centrifical, initial, and vacuum advance. Most of your fuel delivery at highway cruise is supplied by the idle mixture screws and off-idle passages.

 

yea it sucks having to fill it up after a long night, i dont have a working speedo or odometer but i cant imagine me getting double digits in gas... i also drive "more fun" when there is noone around on the roads...

 

I just put on a new carb, the old one wasnt working right. The car is quick, but man gas miliage sucks. I went across town and dumped a quarter of a tank. At $3.00 a gallon thats not good. I just heard gas hit a record 70. a barrel, so fill up. By the end of april $3.00 will look good.

 

you said it, I think it is all how people drive the car is how good their gas mileage will be, if you drive it like it is a quick car then it will be a quick car that is bad on gas, if you drive it like a slow car it will be a car that has the potential to be quick and get decent gas mileage...

 

Last time I did the calculations for my gas milage, I ended up with 12mpg doing all city driving. I drive like a granny most of the time. My only mods are the addition of Hooker 2055s, a Catco high flow cat and Hooker catback.

I think the EPA average for LG4s in 1985 was something like 15-17 mpg. I think I'm losing 3 to 4 mpg just because my carb is way out of whack. I've fixed just about everything I could think of that would cause bad milage, but the carb has been untouched since I bought the car (and I know the previous owner fiddled with it a lot, in an effort to keep it idling). Does is sound feasible that I am losing that much just because the carb is old and untuned?