Backfiring and iddle drops... different stuff at different temp

[Nacho-RT74]

Hi... as you read, I have backfiring when suddenly press the gas pedal when car is cold, and iddle drops almost to die when I'm riding and stops the car when is hot.

Also when car is cold and put in drive, idlle drops enough to get discharge read at ammeter ( in park or neutral I have needle in the middle or slightly to charge side ). Of course when is hot, this stuff increase. At night that is not good since I'm getting battery discharge. I don't want to get the A/C working untill get this stuff fixed, because will get battery dead frequently.

I have openend the carb several times and discovered a leak on bowl wells ( thermoquad ). already and theorically fixed. Lats time I opened didn't get any leak evidence on lower plate of carb.

SOMETIMES when engine is hot, starts inmediatly, BUT with missed idlle ( erratically ) untill I press gas pedal enough to get iddle again.

laters times I have opened the carb, floaters lever are set on right position ( 1" ), but some times in the past I got float levers out of adjusment.

New air filter.
New O-Rings on Carb.

Distribuitor timmimg is set on around 10 º.


I'm gettig also high temp reading frequetly ( around 3/4 of gauge reading ) but maybe is because I need new lower hose and a good radiator cleaning. 190 º Thermostat ( I had practically same reading without thermostat ). this reading started when I changed the cluster from standart to Rallye one, but my car was parked around a year and a half for a while I was upgrading it, that's why I think could it be just dirty radiator. Clutch fan is new. Water pum recently rebuilt.


I was thinking on damaged gas pump... what do you think guys ?

[Chryco Psycho]

if it backfires as the carb is opened it is going lean so either the check ball under the squirter is missing or the squirter is too small, the backfire will burn some of the fuel in the intake & cause ti to stall
to stop the discahrge at idle you either need to increase idle speed or use a smaller pulley on the alt to spin the alt faster , discharge at idle is relatively normal as the altis not spiinign fast enough to create more current than is being drawn by the ign & lights
often the engine will become slightly flooded when sitting hot so when you restart it will fire but is rich until the carb is opened up to correct the rich condition 

[Nacho-RT74]

alt situation is relativelly normal, yes, but I remember have had charging system working better than now, in fact centered even at night with lights on or allmost unnoticeable variations. Pulley is the same, and I think is the smaller of all I can find. I think actually is more related with the actual missing iddle stuff.

squirters... good point. I'll check the needle. I know is there, no missed, but maybe is stuck somehow.

now... engine miss iddle when I stops the car on transit and is hot... it looks that floods like when floaters are out of adjustment or with a leak. just a clue. Could floaters would need a custom set up ?

idles erratically when I start the engine when is hot... is not common when it happens but... just mentioning what did happen yesterday.

anyway all fails look to be related with lean mixture, the deal is to find where is the lean stuff.

-Floaters.
-Leak.
-Gas pump to much preassure and floaters needles unable to stops gas.
-Squirter... could it be also on rest of fails when is hot and needle doesn't close the gas circulation droping by gravity and/or ventury temp pressure difference ? it sounds some crazy, but ....


Could it be all that fails a bad timming set up ? dist vacuum ? vacuum is relativelly new, Original Mopar 9 lbs.

I'm reading on several threads about timming at idle around 15 º, but Haynes manual it says 8 º... what is the true ?

[Chryco Psycho]

haynes is the factory setting , the allen screw inside the vacuum pot needs to be turned counterclockwize , each turn reduces the advance approx 1* , set the total timing at 36-38* at 3000 rpm then see where your timing is at at idle you need to shorten the curve down so you have 14-18* at idle to run best .
If  the   floats are set too low it wil run lean above idle speed , , if the floats cannot stop the fuel flow it will run rich not lean , the common cause for lean at idle is either the mixture screws are adjusted in too far or the bleeds on the idle circuit are too large & you are not getting enough vacuum signal on the idle circuit