spitting thru carb when cold

[georgeramos]

I have a relatively new DFEV and since my recent pertronix install the car spits and pings thru the carb when cold. Once it warms up it stops. Could it be choke related?

Thanks

[vandor]

Backfiring into the intake usually means the mixture is lean. Make sure the choke works properly.

[georgeramos]

It seems like the choke does not work at all... i let the car sit for about 4 hours then tried it. it started but the butterflies on the carb did not move. The electric choke is getting 12v. if the ambient air is warm (about 80) will the choke not operate?

[vandor]

I think you have to press down on the accelerator pedal to activate the choke. Did you do that?
Is the choke butterfly completely vertical? What is the ambient temperature?
You may not get much choke action if the temperature is over 80F.

[georgeramos]

It is about 80 degrees. Choke butterflies were about half way open but i never saw it move. I did press pedal yes i read that onlne somewhere. I will test it tomorrow morning. Im sure the temps will be much lower outside.

I would suspect timing but the issue goes away once the car is warm so i think that points to the carb is that correct?

Thanks

[vandor]

Yes, likely a carb or vacuum leak issue.

[majicwrench]

IF it ran ok before Petromaz ignition, and runs poorly now, is pretty obvious that the issue is the ignition, not the carb.

[georgeramos]

I find that whenever I change or "update" some system invariably another system will be affected in the aftermath. i know it makes no sense but it certainly seems to be the case for me.

What ignition or timing issue could present itself when the car is cold and clear up once it's warm. It presents itself as spitting and backfiring through the carb upon acceleration from stop.

[RoyBatty]

Did you change the timing when you installed the pertronix and hotter coil?
This combination could be firing the lean mixture you seem to have on a cold engine, better than the old stock ignition could.
Try adjusting your timing 5 degrees either direction and see if it has any effect.

[georgeramos]

Yes i changed the timing so i will try that Roy.

Thanks

[georgeramos]

Update: chilly morning I activated the throttle and the butterflies closed. Car fired up first crank and idled well. i let it idle for about 7-8minutes as ran to get/set up my timing light. It is steady at about 10 degrees BTDC. After I checked that I slowly activated the throttle and it spit gas up out of the carb.

If timing is the issue I believe it needs to be more advanced right?

[vandor]

10 degrees advance is right for idle speed. Can you see it advance when you rev up the engine?

[georgeramos]

i retarded it to about 8 degrees advanced and its running great with no backfiring while cold. Now on to the next issue- cooling system. Which was refurbished 1.5 yrs ago - is acting up again...

[georgeramos]

I spoke too soon. I am still experiencing backfiring through the carb under initial load while cold. I may need to take it to a shop for this one...

[RoyBatty]

I believe your choke is opening too quick for your install.
There should be three screws around the outside of the choke spring housing.
Index the current location of the spring drum relative to the housing.
Loosen the three screws, and with the throttle held to the wide open position, adjust the position of the spring drum to more tightly close the choke butterfly. Just a little at a time. You will see that as you rotate the drum, that one way opens the choke more and the other way closes it.
Now test drive and see how it behaves. Once you are happy with the cold start/warm up driveability, recheck that when the engine is hot that the choke is opening all the way.
Good luck.