Mark A Shields

I have an Edelbrock 600cfm carb. I just put new wires and spark plugs in because the carb would backfire when started and put underload even if warmed up. Thought maybe it could be crossfiring. That wasn't it. Now someone also told me that it could be running lean. How do I correct this. Do I do this buy the 2 screws for air/fuel mixture.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

Jer82Z28

It could possibly be a lean condition thats cause your backfires
if you want to change jets/metering rods you will need to buy the carb kit, which includes several different sizes of jets and metering rods. before you do that though, make sure your aircleaner is clean, and also your fuel filter. If you want, you can play around with the accelerator pump, there is a linkage to it from the throttle linkage, there is an arm that pushes down into the carb as you press the gas, there are three holes in it. move the linkage up a hole to add more fuel when you step on the gas. that might solve your problem.

Damon

The 2 screws you refer to, Mark, are the idle mixture screws. Yes, you can and should play with them to get the best idle possible.

Start them an even number of turns out from fully seated (like maybe 3 turns). Get the engine fully warmed up, make sure the choke is fully open and then start adjusting the screws 1/4 turn at a time. Make sure you do this evenly side-to-side. Go leaner until the idle slows and then back it off about 1/2 turn. That'll get you in the ballpark.

If your popping or hesitation happens above idle speeds though, adjsuting the idle mixture screws won't help. For that you need to dig into the carb and start playing with jets and such.

Mark A Shields

I read in the carb. manual trouble shooting area that it could be to a choke problem. I don't know **** about working on cars so I'll have someone look to see if the choke needs adjusting.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

MightyMouseMtr

Was it running good before you put the carb on? IMO most of time it's not the carb that makes it backfire out of the carb. It's usually you have the distributor off.

Also when you look at the vacuum can on the distributor is it pointing barely to the back of the passenger tire?

Email me since I don't get around here if you want me to take you through it.

MikeS

Do you have the instruction manual that came with you carb? If not, I am pretty sure they have them online at edelbrock's web site. It covers everything from checking/adjusting the choke and floats, to changing jets and metering rods. I'm not sure what the problem is, but it is an easy carb to work on. I'd reccomend reading that manual. I think it explains the carbs pretty well, even if it doesn't help with your specific problem.