Need advice on carb set up

[red 69 runner]

Heres what I got going on.Stock 69 383 HP,I just replaced the stock cast iron manifold with a Weiand dual plane aluminum one that looks like the stock one,brand new Edelbrock 1406 carburator.I installed the manifold and carb,it seemed to run fine right out of the box but I didnt fool with it to much because I had a guy replace the points ignition system wit a MP electronic setup with the orange box,the guy that set it up said he had the total timeing set at 40 degrees.the car starts and idles fine and driving it is ok to but here is what is bothering me after replaceing a broken motor mount(was broken since I had the car explains why it would nt spin the stock 14" tires)so I tested out the new motor mount by flooring it and it smoked the tires but as soon as I let off the pedal the car stalled,started right back up and ran fine but now today I pulled it out of the garage and was it letting warm up and the temp was about 77 degrees here today but the exaust was very visible like it was 30 degrees outside,had a very rich smell.I asked the guy that set up the new ignition about the stall after flooring it and he said to call Edelbrock.I am not very good at tuning but am willing to learn,I dont know if I need to make adjustments to the carb or what,Edelbrock carbs come set up for economy not performance,any help would be greatly appriciated.

 

[benno440]

what cfm carb, it is possible over fueling, can cause it to satll also, i would call edelbrock or get on google/youtube and learn how to tune it

 

[red 69 runner]

Its a 600 cfm,I forgot to mention that if I slowly push on the pedal with it in park when it gets around 2300 rpm it sounds like a cylander drops out and runs rough but will acelerate ok if you just push it fast,while driving if you floor it WOT,it runs great,could there be a problem with the valves maybe needing to be adjusted?.

 

[Garys1969RR]

In stock form, you cant adjust the valve lash unless you shim the rocker arm shafts. So it sounds like a carb or maybe a distributor problem. If you are running 40 degrees total timing, thats alot. Try 36 or 38. Also those engines seem to work better with alot of initial timing, like 16 to 18 degrees timing at idle. With the vac advance line un hooked. To do this, you need to limit total advance in the distributor to about 18 to 20 degrees of centrifugal advance. So with your initial 18 deg at idle, and another 18 in the dist, you end up with 36 total. But the distributor must be removed and disassembled to make the modification. Ok try that.

 

[Meep-Meep]

I have a hard time believing a brand new carb runs that bad out of the box. Assuming you engine is stock or very mild it should run pretty well aside from minor tuning. Do you have your vacuum advance hooked up to the ported port? Try disconnecting it and repeat your slow RPM test (plug the hose of course). If the problem goes away you may have reluctor phasing issues with that distributor.

 

[daredevil]

Pull the plugs and read them.Could be running lean if it accelerates well when floored but hesitates when slowly mashed. Pump shot could be compensating. And I agree 40* sounds a bit much. I like around 36*I would worry at 40* its detonating and you arent hearing it.I would check fuel pressure also.

 

[red 69 runner]

Thanks,I will try that test tonight when I get home,Talked to the Edelbrock tech line and he said to move accelerator pump linkage rod to the very top hole and back idle fuel mixture screws out 1 half turn.linkage rod was in the middle hole.tried that and still stalls after flooring and letting off.talked to the guy that set up the ignition and he wants to recheck everything now that the motor mount is fixed,I thought he said 40 degrees total timingbut it is only 36 or 37.he also said could be something with the distributor..I will keep you posted,thanks for all the usefull info.

 

[red 69 runner]

Meep you got it right again,I unhooked the vac advance from the distributor and plugged it off at the carb and the motor runs smooth when I push the pedal down all the way past 2000 rpm.ran out of time tonight so I didnt drive it .talked to my guy that set it up and he said he drive it and see how it acts,do you really need the vac advance hooked up,he says no but we might have to re-set the timeing,he set total at 38 degrees,so I will let you know how it acts when I drive it tomorrow.

 

[Meep-Meep]

I had a feeling....

You do want the vac advance for street driving so I recommend trying another distributor for the sake of simplicity, or another vac can. Or you can check how many degrees your vac advance is putting in. With the engine idling pull a vacuum on the hose and record the amount of advance. A basic setting should be about 10 degrees. If you get way more than that then you need to dial that back some. Some distributors have an allen screw that is accessible through the vac port. Give it a turn (CCW) and see if that brings it down.

 

[red 69 runner]

Thanks I will look into that,my distributor has that allen screw adjustment and the instructions for tuning that part were in the kit I bought from MP.