carb help: backfires thru carb, stalls and shoots flames

[lasvegas69charg]

i really need some help here.  when the engine was on the dyno it ran great and started up fine with very little backfiring thru the carb.  since i have installed it in my car it takes awhile to start up..its about 10 mins of backfiring thru carb, stalling, spraying gas out of the carb when stalls and shooting flames out thru the carb.  once the car is warm it starts right up without any problems.  i have a quickfuel 750 slayer series with vacuum secondaries.  at first i thought maybe my dist is out 180 deg but once the car in warm it starts right up. i also notice when i did drive it for the first time and the engine was warm it would stall and backfire thru the carb.  the floats are set right in the middle...i have even locked out the choke and still does it. the fuel pressure guage is at 6 psi.   any suggestions...

[Cooter]

Have you messed with the timing any since dyno time? Carb? Changed anything?

Sounds like timing is WAYY late (Dare I say it??? Retarded)....

[lasvegas69charg]

i havent changed anything since the dyno.  Once the car is warm it starts right up and revs up without a problem but it does backfire and stall when driving it

[bobs66440]

Double check the spark plug wire routing. It sounds like two may be switched. Or maybe a plug wire is arcing...

[charger Downunder]

I bet its too lean on start up don't lock out the chock give it more at start up.

[Cooter]

Without more info like maybe something done different during install of engine, diagnosing this over the internet is gonna be like trying to give someone a haircut over the phone.

[lasvegas69charg]

I didn't change anything. Once the car is warmed up I use one if those infared digital thermometers to check to make sure all cylinders is firing and everything checks out ok. I shut the car off for a hour and go back to start it and it fires right up.

[lasvegas69charg]

would the car start and run if the timing was out 180?

[WhiteOnGreen]

i havent changed anything since the dyno.  Once the car is warm it starts right up and revs up without a problem but it does backfire and stall when driving it

Vacuuum advance fail?

[XH29N0G]

Read this with a grain of salt, there are others who know way more than me on this.  

I am not sure that it will settle in and then run 180 out.  I know that it will make it backfire because I did that.  It did not start.

The first thing I would check would (like the other responders) would be timing.  I don't know if I missed that you already checked that.  It does not seem impossible that the distributor might rotate a little.  

It could be way lean, but I would think that would show up on accelleration, not start up (Others correct me if I am wrong), it could be the choke (colder temps) but that would go away.  Is it electronic ignition?  My guess is no, but if not, check dwell.

I think a backfire through the carb generally means there is a path for the spark to the carb when the spark fires.  (Don't recall why lean backfire occurred through the carb though).  So I think the rule is to check ignition related things first, and work from there.
 

[johnnyseville]

Some things come to mind, timing is first, definitely check it, if you did not move the dist, maybe the chain jumped a tooth.  Sticking valves is another possibility, more so when cold.  Also maybe the lifters need adjusting, both hydraulic and solids, not sure which you have, but the lash will vary depending if hot or cold. 

[warpspeed]

I have found that if the carb backfires, it is lean.  If there are backfires in the exhaust, then it is too much gas or too rich!!!  Could be too little fuel too?

[lasvegas69charg]

I am just going to start over. New plugs, reset carb settings, check carb operations, verify tdc and timing on number 1 piston, spark plug wiring, timing and lash adj on valvetrain.  Hopefully that should verify everything.

[lasvegas69charg]

well i pulled out the plugs today and they are wet from fuel and completely black.  i took the carb apart and check to make sure the float was clear and not sticking.  set the setting back to initial settings(idle mixture).  the next step i will be putting #1 piston at tdc and checking to make sure rotor is setting on #1 wire, and check wiring firing order.....the carb is completely black in the inside..should i take it off to clean it or is it ok to clean the inside with carb cleaner on the car?

[red69superbee]

you said you locked out the choke? You need the choke to be closed to start and gradually open while it warms up, that is why it pops up through and blows flames and all that.Its black inside because it keeps popping back through the carb.Also if it was run on the dyno, its inside a building where its nice and warm and doesnt need a choke to run.Set your choke properly and i think youll find everything is fine

[lasvegas69charg]

ok.  Its a quick fuel slayer series electric choke. In the directions it says to loosen the 3 screws and rotate ccw for richer choke and cw for leaner choke but it doesn't tell you where to set it. Any suggestions?

[resq302]

I seem to remember when I was rebuilding my Carter AVS that the choke setting was something like 1/8" gap between the choke butterfly and the housing.

[RIDGERACER383]

My car did the same thing and kept fouling plugs and backfiring..I had points on it and switched to a electronic setup,new plugs and wires.That fixed everything and runs like a champ.Mine doesn't have a electronic choke on it either.

[resq302]

When we had the backfiring through the carb on our el camino, it ended up being that it was dumping raw fuel down into the engine at idle which was pooling up gas inside the intake.  The company who rebuilt it ended up having to rebuild it again on their dime.  They also couldn't rebuild the carb on my charger to save their life either.  Since then I have never used them again.

[red69superbee]

yeah, hold the throttle open a little bit so it will let the choke linkage work right.Turn the cover so it make the choke close lightly.Tighten the screws.Turn loose of the throttle, the choke should stay shut.If you pump the gas one time when you start it, it should run as long as you dont touch the gas after it runs, if it wants to die, just let it die.Pump the gas two times and restart without touching the gas.If it runs now it should be on fast idle.The way to make it not fast idle is move the gas when its running.If its not ready yet it will die again.If it still seems cold natured, turn the choke cover tighter just a little bit more, if it floods as it warms up the back it off just a little

[lasvegas69charg]

well after going thru everything I found the problem. the power valve in the carb was bad. I changed the power valve and the car fired right up with no more of the backfiring thru the carb or catching fire.