Gas mileage???

[bluex]

What do you guys get?

With my somewhat stock (bigger cam and headers) 350 (.040) and the TH350/3.08's I got around 10 MPG.

What can I look for out of the new setup in my sig? (361/700R4/3.08). The motor has flat top pistions (4 valve reliefs), 882 heads 224/224 summit cam, edel performer rpm and a 1406 600 carb. It has a 'vette stall in it supposed to be around 2k stall.

Is 15-16 too much to ask???

Thanks
Paul

[Destructo]

I get about 12 with my 85 K10 mostly highway driving, Its pretty low compression with a mild cam, weiand intake, headers and exhaust along with some recurving and higher output ignition. Thats with running my 700r4 in 3rd gear on the highway because with my Q-Jet not running properly it wouldn't make enough power to cruise on the highway in OD.

[aliencheyenne]

You need to swap gears. 3.08 with a 700R will be a dog in 4th.

[TIMSPEED]

Originally Posted by aliencheyenne

You need to swap gears. 3.08 with a 700R will be a dog in 4th.

Maybe..but the 1st gear launch will be GREAT! (700R4 has a 3.06 first gear, as opposed to the TH350's 2.5x)
With my truck, I get about 12mpg. Truck is in sig, Goodwrench 350 crate motor, TH350, 3.42 gears, 28" tires, all city driving.

[76sierraclassic]

I checked mine after a short highway trip this past weekend and it right at 15 mpg. I have a '76 GMC Sierra Classic Longbed with a tired 100% stock 350/th350 with a 4bbl Q-jet with 140,000 miles on it. I don't know what gear ratio I have in the rear end though. To get that kind of mileage (which I was totally impressed with) I drove it fairly conservatively. I ran about 60-65 mph (hit 70 occasionally) and took it easy when it came to passing other cars.

I figure that my "normal" in-town driving is going to be around 13-14 mpg.

Mike

[bluex]

Originally Posted by aliencheyenne

You need to swap gears. 3.08 with a 700R will be a dog in 4th.

Thats the plan, but right now I'm broke from building the motor. Eventually I want to go through the rear, new gears (3.42 or 3.55), and posi and new bearings all around. That will be a while though, and if I like it with the 3.08's they might just stay!!

76> I wish I could have gotten that kind of mileage with my old setup. My truck was a longbed too and I know that there was no way it was getting any better than 12. Must be a huge difference between our driving styles!

[76sierraclassic]

Originally Posted by bluex

76> I wish I could have gotten that kind of mileage with my old setup. My truck was a longbed too and I know that there was no way it was getting any better than 12. Must be a huge difference between our driving styles!

Well, with the # of miles on mine, and the lack of funds should something happen, I have to take it a little bit easy. I already have a lifter clacking, and a decent oil leak somewhere, so I have to keep the RPM's and speed down a little...oh, well.

Mike

[Grande Rojo]

8-12mpg but mostly 8

[piecesparts]

My son has an 86 chevy with a 350 and a 700 R4. The truck originally had a 305 with a 350C tranny and 3.08 gears. The gear ratio with the 700R4 created a mess. The truck ran down the highway at 1900 RPM (70 MPH). The cruise control was always kicking down to get the thing up a hill. The gas mileage was a strong 12 MPG. We put 3.73 gears into the rear end and brought the RPMs to 2500 at 70 MPH and gained 2 MPG, since the engine is now in a good power curve and the cruise works normally. I myself have an 84 GMC pickup with a 383 stroker motor, 700R4 tranny, and 3.73 gears. This engine is good for 400 HP and I get 15 MPG, so there is a good thing about being in the curve. By the way both trucks run on 28" tire diameters.

[GMC1tondually4dr]

Gear the truck to stay in the fattest part of its torque curve, Don't gear it for top end, figure at what rpm the engine is working at mostly, then gear it for that. All passenger vehicles are geared for a compromise, you can narrow that down to mostly city ,mostly highway or whatever.

Just my .02

CCDually

[cliffsta]

i get a measely 12 - 14 MPG in my 1980 C10 with a 305. But i think it might be better than that cause i spend a lot of time in the driveway warming in up so it will run. is that bad for a 305 MPG wise?

[piecesparts]

Define a lot of time. There is nothing wrong with warming a motor up, but don't overdo it, a few minutes in the summer to get the oil through the motor and then drive. Winter will be a little different, but once again, don't overdo it. If it takes a lot of time to get it warm enough to drive then there is probably more wrong with your motor than gas mileage. Measely 12-14 MPG is a standard for most trucks. You have a 4000 lb brick wall that you are driving, and in the 80s the efficiency was marginal compared to today's motors. The smog pump, EGR, catalitic converter (when installed), exhaust system, shoe box (carburetor) and the electronic ignition were all prehistoric to some of the better designs of today. The 305 power curve is different than the 350 and the truck is probably geared with 3.08 gears and a "350C" transmission. The 350C is a inefficient upgrade to the standard 350 transmission with a lockup converter. If the lock up feature is not working right the engine will use more gas.

[Bill W]

78 chevy 4x4, SM465, 3.73, 31 inch tires. 14 miles per gallon.

Bill

[alpha_male0203]

i get around 10 to 12 around

[Russell]

Getting around 11 with my truck running like a peice of crap...

[screwballl]

Originally Posted by 76sierraclassic

I checked mine after a short highway trip this past weekend and it right at 15 mpg. I have a '76 GMC Sierra Classic Longbed with a tired 100% stock 350/th350 with a 4bbl Q-jet with 140,000 miles on it. I don't know what gear ratio I have in the rear end though. To get that kind of mileage (which I was totally impressed with) I drove it fairly conservatively. I ran about 60-65 mph (hit 70 occasionally) and took it easy when it came to passing other cars.

I figure that my "normal" in-town driving is going to be around 13-14 mpg.

Mike

wow your stats sound very similar to mine. with ym 76GMC c1500 LB, i have the stock 4bbl rochester on a tired 350 and around town i average 15mpg.. i think my carb is running a little lean tho

[Jonboy]

87 350/700/3.42's and I have been averaging 16.5-17, which is a ton better than I was expecting. I do drive interstate a lot, though.

[1980 Chevy]

I've got a 454 with Holley 750 carb. 8 mpg.

[cliffsta]

not long warmup, just everyday before i start driving it i gotta warm it up for like 2-3 minutes, revving it and holding a little gas, but once its been started for the day it prrrrrrs like a kitten, except for that leaky muffler and clogged cat converter. (see my other post entitled carb, cam and timing) And since i drive it almost everyday thats probably 10 minutes a week im sitting in the drivway in park giving it gas. But hey man i'm not complaining about 12-14, i love my truck.