318 exhaust pops occasionally at idle

[MoparMuscleGuy]

My exhaust pops occasionally at idle and idle only. No backfiring.

I have a question for you guys. I have a 74 dart with a 318. When I bought it, it was in need of a tune-up. I changed the fuel pump, fuel filter, oil, and oil filter, air filter, pcv, checked all lines for leaks, plugs, plug wires, cap, rotor, distributor, new factory holley 2 barrel carburetor. Reset timing for factory setting of TDC. The car starts and runs great, Idle is about 700-750. Idle is perfect in park but when you put it in drive the idle is not as smooth. When driving, the car runs and drives great with smooth engine purring like a kitten. I've never had a V8 exhaust pop like this before. It's not horrible and have read online that my performance exhaust may lead to this. I have also read that some people like this. The car has hooker headers that were on it when I bought it. Does anyone have this same problem?, if it is a problem. Looking forward to a little feedback.:read2: P.S. I've played with the timing from TDC to 10 BTDC. Doesn't seem to help.

 

[toolmanmike]

Sounds like a burnt valve or maybe carbon build-up. I would try some liquid carb cleaner or carbon blaster. The instructions usually say to warm the engine
up, jack the idle up to 2000 rpm, and trickle the liquid down the carb. You usually all sorts of stuff blows out of the tail pipe. toolman

 

[SRT_DSTRHOLC]

sea foam...or maybe ur cars running a tad lean?

 

[MopaR&D]

Keep your timing at 10* BTDC, and try tuning your idle mixture if you haven't already. I think you have a burnt exhaust valve seat if you get consistent missing at idle. How many miles are on the engine?

 

[MoparMuscleGuy]

Keep your timing at 10* BTDC, and try tuning your idle mixture if you haven't already. I think you have a burnt exhaust valve seat if you get consistent missing at idle. How many miles are on the engine?

Went back to 9 BTDC. It's a brand new two barrel holley(factory settings). Only adjusted throttle screw so far. I wanted to get an opinion before adjusting idle mixture. From what I can tell there is about 65,000 miles on it since the rebuild.

 

[rumblefish360]

Also note, that the OE or even OE styled ignition does misfire. The headers add to issues like this due to a leaning out of the cylinder.

 

[MoparMuscleGuy]

Also note, that the OE or even OE styled ignition does misfire. The headers add to issues like this due to a leaning out of the cylinder.

I plan on going back to stock exhaust manifolds. These headers that someone put on it are more for a performance engine not a two barrel 318. I'm just interested in the old school stock engine for cruisen. I've learned something new about the oe ignitions, thanks. Do you think the headers could just be amplifying the noise? Anything more on the oe ignitions?

 

[rumblefish360]

Headers amp'in up noise. As sure as theres a sun burning.

I'm not the best to ask about ignitions, I just know what I like, LOL. I've read a few books on the subject and drove a few tech's mad, but as far as a stock ride for cruise, I'd still use a powerful box. For the OE look, I'd use the MoPar Chrome box with proper resister.

A MSD or equal like type box is better since the multi striking spark is very good for low RPM rides. It will increase your mileage and run smoother, start quicker like they claim. You can paint it black and hide it under the battery tray. Well worth it IMO, hands down.

 

[clhyer]

When did you buy the car? How long did you wait before you gave it the tune up? Did it have that pop before you tuned it up? Check your plug wires to be sure that you don't have a pair crossed up. Lift the hood at night with the engine running in the dark. If you see any arcing from a wire you have a bad wire(s).
Just a couple items to check that are easy and cost nothing.
C

 

[MoparMuscleGuy]

When did you buy the car? How long did you wait before you gave it the tune up? Did it have that pop before you tuned it up? Check your plug wires to be sure that you don't have a pair crossed up. Lift the hood at night with the engine running in the dark. If you see any arcing from a wire you have a bad wire(s).
Just a couple items to check that are easy and cost nothing.
C

No popping before the tune-up. After the tune-up it ran better than ever. After a couple hundred miles I noticed this occasional popping. I wonder if it could be some bad gas?

 

[sublime green]

The 340 was doing this today. Probably the fact it hasnt been started in a while and needs to be timed a little. Will also take into consideration the other things listed here to get it back on track.

 

[morepowertoya]

i would readjust the mixture screws out 2 to 2 1/2 turns, then see how it runs.

 

[Ptdartfreak]

does this cause worse gas milage as well my car has been having this issue