318 backfiring

-
69KillerFish

69KillerFish

Well-Known Member
Joined
Mar 2, 2014
Messages
163
Reaction score
23
Location
Washington DC
I had to park my Cuda for a couple of years. I would occasionally start it and let it run for a while. I had to move my car to another space. When I tried to start it, it was backfiring thru the carburetor and exhaust. It would barely stay running. I checked points, plugs and wires, all good. Rotating the distributor to advance or retard didn't help. I would check the timing but it wouldn't run long enough to test it. When I rebuilt the motor many years ago, I removed the original chain that had nylon teeth and installed a metal chain and new gears. I'm suspecting the timing chain jumped a tooth. Any thoughts?
 
Points ignition? You probably need a new condenser.
 
Hydraulic cam? Any noise from the lifters? How much oil pressure?
 
Cheapest thing to throw at it is a new set of plugs.
 
Mopar69gts said:
I'd look at the carb / fuel...etc
If it sat for years.
Click to expand...

I cleaned and rebuilt the carb a number of years ago. I added sta-bil in the tank while stored. I put new gas filters on for the carb and in the tank. I also put fresh gas in the tank before I attempted to drive it to it's new home.
 
sounds like a lean snap through the carb. That would also explain why you can barely keep it running.
 
Most likely cause, considering the fixes already attempted, is stuck valves...which may have been converted into bent valves....
 
Ballast resistor on the firewall.

Rule #1
When a motor was running and quits; don't randomly move things like the distributor or idle screws. This stuff typical doesn't move itself so why would someone want to fix something that ain't broke. Instead focus on parts that can go bad like points or gas or ballast resistors.
 
Them dang ballast resistors I've replaced 2 this year on 2 different vehicles. I'd replace that and the points right off the bat. At least clean up the points eith some fine sand paper real quick. Try it if that dont work pull valve cover tap each valve with brass mallet and try again.
 
RustyRatRod said:
Might be bad gas.
Click to expand...

Asshole A02.jpg
 
Josh owen said:
Them dang ballast resistors I've replaced 2 this year on 2 different vehicles. I'd replace that and the points right off the bat. At least clean up the points eith some fine sand paper real quick. Try it if that dont work pull valve cover tap each valve with brass mallet and try again.
Click to expand...
Stuck lifters, I would drip trans fluid down the pushrod and let it set for a few then give em a tap. This worked quite well.
 
Might be water in the gas, which happens naturally with changes in temperature and humidity.
When the water gets into the bowls it is reluctant to leave.
To prove it, just drain the Primary bowl into a clear glass container and you will see it cling together in the bottom, looking like a slug of some kind.
If you find water, you have two choices, pump the tank dry, or add some acetone which will bind the water to the gas and make it easier for the water to pass thru the jettings.

If water has sat in the bowls she will likely need to have the fuel wells cleaned out.
 
69FBCuda said:
Stuck lifters, I would drip trans fluid down the pushrod and let it set for a few then give em a tap. This worked quite well.
Click to expand...
This is what I was getting at in post 4. But didn’t get an answer.
 
Fresh gas doesent fix the old fuel in the tank and in the lines. Sea foam and sta-bil only work for so long. Can still gum up the carb.
 
69KillerFish said:
I had to park my Cuda for a couple of years. I would occasionally start it and let it run for a while. I had to move my car to another space. When I tried to start it, it was backfiring thru the carburetor and exhaust. It would barely stay running. I checked points, plugs and wires, all good. Rotating the distributor to advance or retard didn't help. I would check the timing but it wouldn't run long enough to test it. When I rebuilt the motor many years ago, I removed the original chain that had nylon teeth and installed a metal chain and new gears. I'm suspecting the timing chain jumped a tooth. Any thoughts?
Click to expand...
Does the carburetor squirt fuel when opened? Did you check for acorns ..lol squirrels stashing acorns down the intake/carb. It would have to be one OLD and gritty motor to have stuck lifters already. I've only seen that on old chevies btw, but anything's possible...like acorns n stuck lifters from water getting in...or infrequent oil changes and crap oil.
 
This is why I like forums. Thank you everybody for your ideas. The carb is squirting gas. I pumped whatever was left in the gas tank out, all the gas in the tank is fresh. I'll check the ballast resistor, points and condenser next. If there is no change I will move on to the heads. I'll let you all know how the process of elimination is going.
 
dont even bother with the ballast resistor. Just bypass it for your test. It aint that. Todays **** gas will plug air bleeds and gum up carbs after a while as it is more hygroscopic that regular gas.
 
pishta said:
dont even bother with the ballast resistor. Just bypass it for your test. It aint that. Todays **** gas will plug air bleeds and gum up carbs after a while as it is more hygroscopic that regular gas.
Click to expand...
oooo Mr. Big word. lol
 
Yeah big word, Pishta got it right though. The other day I saw hydroscopic on a forum describing the same thing.....
 
You must log in or register to reply here.
-

Back
Top