Carb Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

KutThroatKustoms · 05-24-2004, 09:16 PM

Alright.. well with the crappy gas mileage we get and the crappy gas prices.

My dads truck has a 350/th350/3.08 gears, drove it ~40 miles today and used almost half a tank, driving it easy. Its old, carb is worn out, etc.

What do you guys recommend for good fuel economy and nothing that will be sluggish.

Edelbrock?

what is everyones opinions on the Road Demon JR 625?

thanks.

79BIG10 · 05-25-2004, 12:49 AM

I love my Edelbrock 1406 600cfm. It's easy to tune and easy on gas. I get 14 MPG on the highway.

aquasharkey · 05-25-2004, 02:01 AM

40 miles on a 1/2 tank! that's terrible! I was having similar problems on my Olds Cutlass with an Olds 350 with a 4bbl quadrajet (I know it's no chevy truck) but the mechanics are the same. check the timing first off. here's what you do. a timing light with an advance dial is the best to have. set it at base timing, remembering to take the vacuum line off the dist. and plug it (probably 8-10 degrees in your case) get someone to plug in the vacuum line back into the distributor while you're shining the light on the timing marks. the mark should jump out of sight, and the engine should speed up a bit. if it doesn't, check that the vacuum hose has vacuum at it and the vacuum advance diaphram is working. if it is, great. also very important, make sure the centrifigal advance is working. there's two ways of checking it. one is to take the distributor cap off and grab the rotor. it should move one way, and then quickly spring back when you let go. the other way is with the timing light again. It's easier if you unhook the vacuum advance(the vacuum hose to the distributor) you can see the marks better. watch your eyes and arms/ etc and get someone to rev it up. the timing line on the harmonic balancer should move around considerably with engine speed. if it doesn't work, you need to take the distributor apart and clean it.
also check the basics (plugs, air filter, tire pressure, etc.) then, if you're still having problems with fuel economy tackle the carb. check for a sunk float, stuck power valve, and leaking well plugs
My exeperiences show if you want fuel economy, stick with quadrajet (I consistantly get between 16-17 with my '75 chev with a newer 305, TH-350 trans w/o lock-up and 3.42:1 rear end)
I hope I helped a bit

05-24-2004, 09:16 PM	#1
KutThroatKustoms drag body or die Join Date: May 2004 Location: Redneck country Posts: 79	Carb Question Alright.. well with the crappy gas mileage we get and the crappy gas prices. My dads truck has a 350/th350/3.08 gears, drove it ~40 miles today and used almost half a tank, driving it easy. Its old, carb is worn out, etc. What do you guys recommend for good fuel economy and nothing that will be sluggish. Edelbrock? what is everyones opinions on the Road Demon JR 625? thanks. __________________ -Bobby-

05-25-2004, 12:49 AM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,774	I love my Edelbrock 1406 600cfm. It's easy to tune and easy on gas. I get 14 MPG on the highway. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

05-25-2004, 02:01 AM	#3
aquasharkey Registered User Join Date: May 2004 Posts: 22	40 miles on a 1/2 tank! that's terrible! I was having similar problems on my Olds Cutlass with an Olds 350 with a 4bbl quadrajet (I know it's no chevy truck) but the mechanics are the same. check the timing first off. here's what you do. a timing light with an advance dial is the best to have. set it at base timing, remembering to take the vacuum line off the dist. and plug it (probably 8-10 degrees in your case) get someone to plug in the vacuum line back into the distributor while you're shining the light on the timing marks. the mark should jump out of sight, and the engine should speed up a bit. if it doesn't, check that the vacuum hose has vacuum at it and the vacuum advance diaphram is working. if it is, great. also very important, make sure the centrifigal advance is working. there's two ways of checking it. one is to take the distributor cap off and grab the rotor. it should move one way, and then quickly spring back when you let go. the other way is with the timing light again. It's easier if you unhook the vacuum advance(the vacuum hose to the distributor) you can see the marks better. watch your eyes and arms/ etc and get someone to rev it up. the timing line on the harmonic balancer should move around considerably with engine speed. if it doesn't work, you need to take the distributor apart and clean it. also check the basics (plugs, air filter, tire pressure, etc.) then, if you're still having problems with fuel economy tackle the carb. check for a sunk float, stuck power valve, and leaking well plugs My exeperiences show if you want fuel economy, stick with quadrajet (I consistantly get between 16-17 with my '75 chev with a newer 305, TH-350 trans w/o lock-up and 3.42:1 rear end) I hope I helped a bit



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