Edelbrock carb question

[68Stepbed]

OK, I finally got tired of my Q-jet staying screwed up all the time so I installed a new 1406 Edelbrock carb on my 305 in my 86 GMC. It runs alot better, but I don't have a good idle. I'm still using the stock air cleaner and stock intake with a carb adapter. The ESC system has been disconnected from the stock distributor and the A and C wires have been looped. I'm gonna try readjusting the A/F mixture screws and playing with idle speed adjustments. I might even try flipping the air cleaner lid over to see if it helps.

Can anyone with experience with this help me? Am I gonna have to use an open filter air cleaner setup? Do I need to swap to a regular distributor?

Any help will be greatly appreciated.

[79BIG10]

What port do you have your HEI connected to on the front of the carb? You need to connect it to the lower port. This will give you full vacuum. Also if you have a vacuum gauge you might want to check to see what it looks like. If you have a leak this will cause the truck to run rough. With a adpater these can cause one. Adjust your timing first to what it should be depending on your engine then try checking the HEI vacuum hose to check for the leaks. This will also help you tune the engine better to create the best vacuum and tune the carb better.

One more thing is you might want to get a tuning kit from Summit or Jeg's. Some local shops have them as well. These are great in fine tuning the carb to what it's needing. Sometimes the springs come in too early late and the rods/jets are the wrong size. This kit elimintates all that.

[HOGDADDY]

I have an 86 also with same carb and I would recomend changing distributors.

[SSC's76]

What exactly is the idle doing, high low?

You can try the full manifold vacuum source for your advance or if your running the full source try the ported. Make certain you have no vacuum leaks or EGR problems before getting gung ho into the carb.

[68Stepbed]

I've got the idle mostly worked out. I need to put a vacuum guage on it to set the idle and mixture screws more accurately. The dist. is next to be changed when I get time.

My main problem has been pinging. Every time I fix something to stop the pinging, it comes back a few days later. I thought the carb would fix it since the dist. has been looped, but apperently not.

I'm gonna have to get a tune-up kit and tune the carb down. It's running too rich. I knew it would be, but I bought the 600 cfm because plans are to install a 383-RV if the 305 ever dies. If not for that, I would've bought a 500 cfm carb.

I really appreciate all the info, guys.

[lurch115]

was the edelbrock new or used when you bought it?? snd the general setting for the idle mixture screws is to turn them in untill they start to slow the motor down and then back them out untill it smooths back out and go another half turn. and as for the distributor..i would change it out with an older vacuum advance style distributor....but if and when you do that make sure that the port you run the advance off of does not pull any vacuum at idle, but does when you rev the motor a little....should be on the lower passager side of the front of the carb.

[lurch115]

the vacuum advance isn't supose to have vacuum at idle...

[68Stepbed]

lurch115, the carb is new. The vac. advance is hooked to ported vacuum.

I also have a new problem, deiseling when I shut it off. Timing is set at 4* initial at idle. I have to turn the idle down to the point it isn't smooth to keep it from deiseling, but it still does shortly. It just acts like it's not burning all the fuel.

Oh Yeah, the gas mileage really sucks now compared to the Q-jet.

[72C203503ONTHETREE]

Sounds like you have a vacuum leak somewhere. Deiseling is caused by too high an idle(you tried fixing that), or hot spots in the combustion chamber which sounds like your problem since you have been running rich and you probably have carbon buildup in your combustion chambers. Try running a can of Berrymans carb cleaner down the carb while the engine is hot and running. Rev it up then pour the can in as fast as you can down both primary barrels until it dies then let it sit a while. That will loosen up the carbon and get rid of it the next time you start it up. GM sells stuff called Top End cleaner that works even better but its not cheap, the Berrymans is cheaper and works almost as well. It worked for me at least in many cars. Have you changed plugs, wires, etc.? May want to try that out to.

[68Stepbed]

I've run 2 cans of thr GM Top Engine cleaner through the engine because I figured carbon was the culprit. I've also run a can of Seafoam. Everything I do only fixes it temporarily.
The truck had a tune-up before I bought it. I just bought some colder plugs(R43TS). I'll get them changed later and see what happens.

I just put the new carb on it last Wednesday, so the carbon buildup from running rich shouldn't be a problem yet, assuming the GM top end stuff cleaned the carbon before.

[72C203503ONTHETREE]

You getting full power from your coil? Maybe the secondary ignition system is weak and cant fire the plugs hot enough to burn the fuel.

[lurch115]

try setting the timing at 6 or 8 degrees.....if that doesn't help, go out to 10 degrees...4 degrees is not usually enough of an advance so what could be happening is that you are getting hot spots from the later sparking and when you shut it off it is igniting unburnt fuel...and with the psark plugs...i'd stick with an R45TS, as i ran into a problem a few months ago because the parts store gave me the R43TS's and they fouled out because they were too low of a heat range

[lurch115]

what are you setting the plug gap at???

[68Stepbed]

I can't set the timing any higher without it pinging. It actually still pings a little at 4*. I haven't changed plugs yet, been real busy. I'll set the gap a .045 on the plugs(that's what is recommended). I haven't been able to work on it at all this week. I filled up last night and put 93 in it instead of 89. It hasn't pinged or dieseled at all last night or this morning. I'll see how the rest of the day goes.

The only thing I can think of is there is still carbon builup in the comb. chambers causing hot spots. Is ther any way I can check for this with the heads on? If I have to take the heads off to clean the carbon, I may get a set of 305 H.O. heads rebuilt. I can take them off the engine out my dad's 87 Monte Carlo SS.

[piecesparts]

WOW---Just about every thing has been suggested, here. Out of all of this do the basics, and then start from there. The problem is probably centered around your distributor (undoubtedly). I would suggest (frist) set the idle screws (with the vacuum gauge--it is the best and easiest) (Second) set the timing to about 10 degrees (slightly advanced), (Third) set the idle to about 650 to 750 RPM with the truck in gear. I actually prefer higher, myself. (Fourth) install new plugs ( I would go hotter than the 43s) and gap them to the factory specs. NOW QUESTION---Have you had the distributor cap off, yet? The centrifugal advance units on these distributors can get rusty and hang up, holding your unit at an advanced condition. You might even have bad advance springs--buy an upgrade kit and put on a slightly heavier spring set. Take the rotor off (get a new one, if you haven't changed it yet) and spray a light coating of WD-40 on the springs and weights (move them to get them free). I see that you have a 1406 carb, connect the carb to the NON-ported fitting, if you want a quicker advance curve--for agressive driving, OR connect to the proted connection if you are a street putterer. Try that and see what happens.
if it were me, I would find a good used one or buy a new HEI unit and install it, get rid of the computer influenced distributor quickly. I figure that is where your problem exists. Once you eliminate the computer, you now have just your motor to deal with and the basics ALWAYS works.

If you suspect you have a vacuum leak, take a can of carb cleaner and spray around your carb base or any intake fittings and the idle will change when it is pulled into the motor.

[HOGDADDY]

Originally Posted by lurch115

the vacuum advance isn't supose to have vacuum at idle...

This is debatable, I for one have mine hooked up to full time manifold vacuum and it runs fine. Ported may be fine with a stock motor but once you change out the stock emmissions quadrajet carb for a Eddy you've pretty much crossed the line.

Check the float level in 2 positions as per manual because this is never right on.