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Better mileage without sacrificing power

swanthog

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swanthog Enthusiast

swanthog

Posted
Posted

Hello, all.

 

I'm preparing to take a lot of road trips this year in my '77 K10. It has a 350 with a 4-barrel Quadrajet. I want to haul my camper and possibly pull another car while vacationing.

 

As we all know, gas prices are outrageous.

 

I was thinking of ways to improve my fuel efficiency without sacrificing any power. One thought I had was that I'd pick up a stock 2-barrel intake manifold and carb.

 

Keeping in mind that I'm running a stock 350, will installing the 2-barrell rob me of much towing/pulling power?

 

Where can I find this manifold and carb? How much can I expect to pay?

 

What are some other low cost alternatives to improving my fuel efficiency?

 

Thank you,

Larry S.

Colorado Kid Enthusiast

Colorado Kid

Posted
Posted

TYpically 4 barrels actually got better MPG than 2 barrels because the smaller primary bores provide better carburetion up to their flow limit, with the big secondaries and their rich jets only opening at virtually wide open throttle. A 2 barrel has bigger bores than the 4 barrel primaries, so it doens't have as good control on the low end, but can't flow as much air as the secondaries on a 4 barrel so it loses out on power too. The only real advantage of 2 barrels was that they were cheap and simple.

 

The only resonalble things you can do for fuel economy on a '79 K-10 is make sure everything is ship shape. Plugs, wires, TIMING, rebuild the Q-jet if you think it needs it, new air filter, throw away the catalytic converter if it's still there,(Dual exhaust is probably worth the effort) keep the tire pressures up and drive it slow. Even when you do all that it'll never do much over 13 MPG highway, cause that's all we ever got from them when they were new and the speed limit was 55 MPH. With a camper and a car in tow you'll be lucky to get 8 MPG. For your use swapping in an RV cam would probably be good . . . more power and possibly a little better MPG under load to boot, but not enough gas savings to pay for the cam.

 

A carburetted 350 in a full size truck with 4 wheel drive and no overdrive, hauling a camper and towing is just plain going to use a lot of gas . . . it's also going to spend a lot of time in the slow lane.

swanthog Enthusiast

swanthog

Posted
  • Author
Posted

Yikes! Ok, it sounds like the 2-barrel idea is out.

 

Yeah, I have hedman headers and dual 2 1/2" exhaust flowing through 2 glass packs. I don't have cats. A funny thing about that: the only reason my muffler guy built the exhaust without the cats was that his book showed that that the truck didn't have them in stock form. This seems odd to me for a '77.

 

I also have new plugs and wires. For the plugs, I went with NGK's because they are shorter and provide better clearance for the headers. For the wires, I went with some high temp 8mm racing wires from Napa. My headers were burning the insulation on the last, lesser, set.

 

I've rebuilt the carb using the kit from Napa. The only problem I have with the carb now is that it revs really high when cold and takes a long time to come down to idle. I usually have to rev it a time or two before it will.

 

--Larry S.

Rookie Enthusiast

Rookie

Posted
Posted

Bingo To the Colorado Kid You nailed that one. The rochester should do you fine but if you do upgrad i'd suggest a edlebrock part number 1406 600 cfm it should do nicely and it should bolt right to your factory manifold.

  • 4 weeks later...
snoman Senior Enthusiast

snoman

Posted
Posted
Throw the Quadajunk away and buy a eldebrock. Just a suggestion!!! :lol:

Very bad advise. If you want gas mileage keep the quadrajet as they were designed with that in mind. 77 were kinda smoggies and had lower compression and retarded timing and weak cams and that is the main reason for poor mileage not carb. (I have been driving for over 30 years so I remember when those truck were new) You might check out a adter market cam. I had good luck with competion cams 252 and 260 back then and I believe they still make them now. IF trailer is heavy and you have 4.10 gears go for 260, otherwise try 252.

citydriver Enthusiast

citydriver

Posted
Posted

A properly set-up Quadrajet WILL BEAT a Holley any day :puke:

You can adjust the Cold Idle setting on that Carb if its too high..there should be 2 screws,1 for Base Idle and another for Cold Idle that seats on the Choke Cam when cold.

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