Carb Popping on Warm Engine Re-Start

[tartan18]

After installing a new EMPI 32/36 DFEV carburetor it is popping when the engine has been warmed up. This does not occur when the engine is cold. There is also significant soot popping out of the exhaust and on the plugs.



I have also been having terrible gas mileage (14 mpg) so a local garage re-jetted the carb for me. My best guess is that my fuel mileage is improved a bit but I won't know for sure until my next fill-up. My car is a 1975 124 but I believe that the engine is from a 1977 (based on the engine's number). In any case it is an 1800 engine. I have the Computronix ignition system and the timing is set at 10 degrees BTDC and the idle is at 900 rpm.

Original jets:
Idle 60
Main 137
Air 165

New jets:
Idle 55
Main 125
Air 150

Here is a video of what I am experiencing:

http://www.youtube.com/watch?v=G9w0T011tuk

Any ideas for my next step would be appreciated.

[So Cal Mark]

Jim
the engine sounds like it has a serious exhaust leak in the video, a very metallic tapping when it's idling. Do you have the plugs gapped at .045? Have you checked valve clearances? With the amount of black smoke, there is unburned fuel in the exhaust and that explains the pop you're getting out the tailpipe. The intake pop concerns me, and that's why I asked about valve clearance.

[tartan18]

The plugs are gapped at .045. I suspected that it might be a valve clearance issue and that is my next step.

[majicwrench]

I'm not a fan at all of "re-jetting" carbs, do you still have the original jets?? Something other than the jets is causing all that. Certainly lots of what sounds like valve noises. And they can pop back thru carb for ignition reasons as well. Check valve clearance, make sure cap is dry/clean inside and all wires good. Something wrong other than carb
Keith

[124JOE]

hows your advance springs?

[tartan18]

I do have the original jets and I will likely put them back in.

No advance springs -- I have an electronic ignition system.

Next step is to adjust the valves. I've ordered the tool and shims.

[majicwrench]

So is all you did is change the carb when this issue began?? It ran wonderful before??

[tartan18]

The problem of popping started when I installed the new EMPI carb. But I can't say the old ADFA carb made the engine run wonderful.

[majicwrench]

Hope you didn't drop something down the intake....