msbz_ls1

iTrader: (1)

Ok..my 86 Chevy Silverado has a 350, edelbrock intake, and edelbrock 4 barral carbuerater..the carburateur needs tuned BadlY!!..im getting about 7mpg if that.now days, is there any way an Amateur can kind of tune it...decently for a little bit better gas mileage..its driven me nuts..

Thanks for any who respond..

I just need a walkthrough on how to...tune it a lil bit...if i Shut the Truck off in park..it spitters and sputters...like its still running..i got to turn it off in Drive, then put it in park then turn the key to off..after it is shut off in park to get it to not spitter sputter, this is how badly it needs tuned!!!

Thanks Again..

facn8me

Go to edelbrock's web page. they have the directions availible.

Texas Terminator

spitter cough cough is cheap gas. sorry. it probably needs rebuilt more than anything. if it is the original carb, probably replaced. if there is much play in the linkage, ie: grab it and move it up and down, it needs replaced. make sure the choke pull off is working. floats are out of adjustment and the needle valve may be leaking too. don't you feel better now?

vanillagorilla

iTrader: (1)

They have very helpful and comprehensive tuning tips there. I wouldn't replace it though, not right away. First check to make sure your timing is where it needs to be (with the vacuum advance disconnected). If that's cool, check all your vacuum lines and look for leaks. That should be done first because its almost free, and you'll never be able to tune the carb if theres a vacuum leak.

Texas Terminator said some good things to check if it needs to be rebuilt. You can rebuild the edelbrock's because they're based of the Carter design and the Q-jet. They're very durable and they can run well for a long time. Rebuilds are easy to do and the kits are readily available.

A few questions though: Did it start running real rich all of the sudden? What was your gas mileage before? Have ever messed with it at all (idle mixture screws, rods, jets etc)?

02sierraz71_5.3

iTrader: (2)

If you dont have money for total rebuild get a good used carb from junkyard, the guys will have some they think are in good repair. if I remeber right theres an adjustment screw on the side of the card for the air to fuel mess with that. I could be wrong though I shore someone will correct me if I am. With the carb do a tune up plugs, wires and adjust timing. Look at the plugs when you take them out, look for any that are fouled and keep in mind the cylinder they came out of. That way you can clean them periodically and put them back in. checkout vacume hoses, egr etc.. they are probably cracked and leeking
all this stuff adds up to bad mileage and other problems.
Ive had some POS vehicles (not that yours is) and all you can really do is keep oil in them. I had a 66 I restored and it had the origional engine in it, I drove it from VA to CA and it made it, burning 3qts on the way at 90 mph.

those trucks new probably only got around 11 mpg anyway
hope this helps

cary00silve

What it's doing is called dieseling, the engine cylinders are running too hot and a creating their own spark (predetonation, pinging, etc.). You can either run better gas, or you can retard the timing a little bit. You may also want to pour some gm top engine cleaner in the carb. This will clean the carbon deposits and varnish which is built up in the cylinder head and maybe increasing compression ratios and hence causing it to diesel out. I have a 1985 blazer, and it's common for it to need adjusting every now and then. Go to www.coloradok5.com they have covered this subject many times just do a quick search.

nuzee

iTrader: (2)

The Edlebrock/Carter AFB carburetor is as fool-proof a carburetor to "get right" out on the market. Many times, they are good to go right-out-of-the-box. However, they are sensitive to high fuel pressure (>6psi) because high pressures can set the floats out of adjustment. It should be relatively simple to check your float adjustment by using Edelbrocks info.

Before blaming the carb for the poor performance, see if what I'm guessing is correct. The engine was having a hard time finding idle so you jacked the idle screw up. Now with the high idle, when you turn the motor off the engine "diesels". Even with the high idle, the engine does not pull smoothly at low rpms. You have to get to around 2000 rpm before the engine runs smooth. Is this correct? If it is, the cause for the poor idle/low rpm behavior is a vacuum leak. Either a hose or connection came loose or check the carb-to-manifold gasket. Another common area is the intake manifold-to-head gasket. Spray carb cleaner along these gaskets and see if you notice a change in the idle quality. If so, you found the problem.

Hope this helps!