Hi, I currently have the electronic Q Jet on the car, I have a Gm 350 along with a 5 Speed, My other mods are in my Sig Below, Just wondering what carb is recommended, It is not a daily driver but I am looking for a good reliable carb,I am also looking for an HEI Dist to go along with it.

By Changing the Carb and Dist is there anything else I need to do? can I just take the Check engine bulb out and worry about it after this?

 

Anyone?

 

The stock carb and distributor will work fine.

 

I have been having a Backfire issue for years with the car, it is constant out of the exhaust on decl, They only thing that made it change was when I disconnect the 4 Pin connector that goes to the Dist, SO I would like to change these parts out and see if that is the issue. I figured changing the carb and HEI may fix issue. I have been chasing the problem for ten years now.

 

Well I ordered these today, hope I made a good choice.

http://www.holley.com/0-76650BK.asp

http://www.summitracing.com/parts/msd-8365

 

Decel pop is likely not distributor related. Could be timing and airfuel related but thats from the chip tune and not actual distributor. Could also be air leaks in exhaust.

 

I tried different exhausts, I even smoke tested the exhaust and verified no leaks, the only thing that helped was dist dist 4 pin wire orif I gave it a touch of gas on decel.

 

Could be lean pops. Usually ecm pulls fuel on decel and the timing thats left in during that low load higher rpms area is high. If its causing the pops it may want less timing. Wont get the strong engine brake feel when decelerating with less timing. It may want more timing but i am not exactly sure what the distributor defaults to when the 4 pin plug is pulled out. I assume base?

 

I believe it is base timing, I think it takes out all of the electronic advance.

 

Base timing and a small amount of advance as speed increases.

 

I hope the MSD DIst works well, I know it wasn't cheap.

 

I dont find anything wrong with gm small cap remote coil setups. Tuning for air fuel and timing likely will help more unless something is wrong with yours. If it seems to run fine normally and verify correct timing at balancer vs commanded, then new dizzy isnt the issue. Its a spark/tune thing. Could just program computer to command less timing if that helps reduce popping

 

Don't know how and don't have way of burning new proms.

 

When I was tuning my Gen 7 I had this problem all it was was unburned fuel in the exhaust I program the fuel to shut off on deaccel no change in timing problem solved.

 

I have no way of programing the proms.

 

You may want to also check your injectors to see if they are leaking, could also cause this problem.

 

There are no injectors in his carburetor.

 

May bad than that is even easier sound like the butterfly's are not closing all the way. Does it ever stay running after the key is turned off?

 

No it does not the car runs perfect accept for the backfire on Decel.

 

What rpm is it idling at?

 

Idles some where around 750 when the choke is not on.

 

Well if it is idliing correctly the only other this is timing. I have seen some after market module do some strange things also to much timing. Also ditributor shafts worn out can cause some wierd things to happen, but usally cause other drivablity issues.

 

Tried stock module and a accel one

 

How much advance are you running?

 

8 initial and then what ever the elec brings in.

 

I don't know what the specs are for that set-up but I know a tpi is 6 initial. May just try some different timing settings just to see what it does. Try 0 initial and go drive and see if there is any change maybe your getting to much advance, also rev it up in nuetral and check to see how much advance it is getting.

 

I had tried changing the time from 0 up to 10 same issue, I forgot what the total was.

 

Well I'm out, still think it is getting fuel when it shouldn't. If you figure it out let us all know I would be curious. Good Luck.

 

I am going to try new carb and dist and see if that fixes it, I just got them today, Going to be a bit before I get them on.

 

At high RPM with the throttle closed the manifold vacuum is high enough to pull fuel straight out of the idle ports, which then burns in the exhaust.

You've got pretty much the worst of all possible worlds for causing deceleration pop... A fuel injection system would cut fuel during deceleration. A more sophisticated EGR system would allow exhaust into the manifold to reduce vaccum. A deceleration bypass valve would lean out the manifold charge. A catalytic converter would burn up some of the excess fuel. A stock muffler would almost completely absorb the noise. An automatic transmission with an overrun clutch would lower engine speed.

 

I have a egr system on it now, I have tried it it with a cat,hollow cat and a straight pipe no change. I have had other carb combos in this car and never had a problem, THis motor is the only one giving me this issue.