Crabby old Newport

[Timsnewporttwin]

Hey Folks,

I asked a couple weeks ago about my 65 Newport. It was at my friends body for about a month. He was having a lot of trouble starting it.

Got the car back and it does have something wrong with it. Hard cold starting, once running it's OK. However now it has a popping type noise when driving, car lags a moment and picks back up. Seems worse in traffic and under a load like climbing a hill. Car does have power and accelerates ok after the popping.
2 barrell Bendix Stromberg carb. Rebuilt a couple years ago, new choke pull of and choke thermostat.

Anyone have a clue ? So far I've been told to take a run down the freeway, maybe bad coil, bad plugs (both have been changed). What might it's trouble be ?

Thank you for reading !

Tim

 

[MEV]

Sounds like water, or moisture in the fuel, or condensation under distributor cap

 

[myskin]

Hey Folks,

I asked a couple weeks ago about my 65 Newport. It was at my friends body for about a month. He was having a lot of trouble starting it.

Got the car back and it does have something wrong with it. Hard cold starting, once running it's OK. However now it has a popping type noise when driving, car lags a moment and picks back up. Seems worse in traffic and under a load like climbing a hill. Car does have power and accelerates ok after the popping.
2 barrell Bendix Stromberg carb. Rebuilt a couple years ago, new choke pull of and choke thermostat.

Anyone have a clue ? So far I've been told to take a run down the freeway, maybe bad coil, bad plugs (both have been changed). What might it's trouble be ?

Thank you for reading !

Tim

Sounds like gas igniting in the carb. If you take the air cleaner off do you see a flame? A bad intake valve will do this. A cracked distributor cap or two crossed plug wires, the vacuum advance not operating (bad v.a. diaphragm, line disconnected from under carb or intake manifold or vacuum port filled with carbon deposits) I seem to remember that the last two cylinders on the driver side could be crossed and you might not notice until you accelerated. But, I’d look for burn marks or cracks inside the cap first. I once floated a lifter that resulted in a bent push rod on a 72 Plymouth with a 400 cid being stupid and overrevving. It also popped. But it was an easy fix. Pulled valve cover and replaced the lifter and push rod without loosening anything. But, I did need a special tool to retrieve the lifter.

 

[myskin]

Sounds like gas igniting in the carb. If you take the air cleaner off do you see a flame? A bad intake valve will do this. A cracked distributor cap or two crossed plug wires, the vacuum advance not operating (bad v.a. diaphragm, line disconnected from under carb or intake manifold or vacuum port filled with carbon deposits) I seem to remember that the last two cylinders on the driver side could be crossed and you might not notice until you accelerated. But, I’d look for burn marks or cracks inside the cap first. I once floated a lifter that resulted in a bent push rod on a 72 Plymouth with a 400 cid being stupid and overrevving. It also popped. But it was an easy fix. Pulled valve cover and replaced the lifter and push rod without loosening anything. But, I did need a special tool to retrieve the lifter.
ps. sorry for the confusion. Somehow I inadvertently posted this inside timesportin post

 

[Big_John]

Hey Folks,

I asked a couple weeks ago about my 65 Newport. It was at my friends body for about a month. He was having a lot of trouble starting it.

Got the car back and it does have something wrong with it. Hard cold starting, once running it's OK. However now it has a popping type noise when driving, car lags a moment and picks back up. Seems worse in traffic and under a load like climbing a hill. Car does have power and accelerates ok after the popping.
2 barrell Bendix Stromberg carb. Rebuilt a couple years ago, new choke pull of and choke thermostat.

Anyone have a clue ? So far I've been told to take a run down the freeway, maybe bad coil, bad plugs (both have been changed). What might it's trouble be ?

Thank you for reading !

Tim

A couple things jump out at me. First is how old the gas? Second, did you change the plugs after getting it out of the body shop?

What ignition do you have?

 

[CBODY67]

One time I got a partial tank of flaky gas. Had to use the accel pedal to keep it idling at a stop light. Got worse. Exhaust had a hollow sound to it. After I figured out what it was, I just drove enough to get the flaky gas used and a new batch in the tank. End of issue.

There are some fuel additives which will make the moisture in the fuel easier to burn, which includes alcohol as their main ingredient.

Download a FSM at www.mymopar.com (if you have not already done so) and get into the Carburetor section on the Stromberg WWC 2bbl carb. Check the choke adjustments! (initial closing via the thermostat and also how far the choke pull-off pulls it open as it starts).

Past that, the base initial ign timing and hot base idle speed. Then the fuel additive, fresher fuel, and put it on the highway for at least 50 miles. More can be better, though. Hopefully, it will get better the more it is driven and new fuel replaces the old.

It is very easy to cross #5 and #7 plug wires. When that happens, off-idle power will take a BIG dump, no matter how much throttle is applied. A customer had a '78 Newport 400 2bbl that his customer's grandson had put new plug wires on. Then it would idle pretty good, but had no power otherwise. I went over to drive it and discovered that it would not even chirp the tires! It was extremely doggy UNTIL the TQuad's secondaries could open and THEN it took off like an afterburner had been ignited. When he checked the wires further, the two rear driver's side wires had been crossed. When corrected, then it acted like it should. As they fire consequtively, no real "miss" was felt, just "no pawer".

"Back-fires" or "spit-backs" are usually ignition timing related. Might also be, possibly, a flaky timing chain sprocket. Timing chain ever been replaced?

Might just be a "build stack" of several contributing factors. First is to make sure the gas in the tank is fresher than it now is, checking the carb operation, tuning issues (to make sure they are where they need to be), before getting more excited about other possibilities.

Just some thoughts and observations,
CBODY67

 

[Timsnewporttwin]

Many thanks everyone ! I pulled a couple plugs, really fouled out. Going to get new ones and possibly change the coil. The motor has not been rebuilt. Unknown miles but original to the car. Doesn't use oil, runs well considering it was a junkyard escapee. Gas reasonably fresh

 

[Timsnewporttwin]

Also, the ignition is original, points, etc. Did check cap looked decent. Don't think it's crossed plug wires, car was fine until recently. Carb rebuilt by a specialist, I'd recommend to anyone. Hoping it's just the plugs. I do drive it easy and it tends to get around town type of drives. So that said I'll get it on the freeway for a good run after the new plugs. Good idea ??

 

[1970FuryConv]

Also, the ignition is original, points, etc. Did check cap looked decent. Don't think it's crossed plug wires, car was fine until recently. Carb rebuilt by a specialist, I'd recommend to anyone. Hoping it's just the plugs. I do drive it easy and it tends to get around town type of drives. So that said I'll get it on the freeway for a good run after the new plugs. Good idea ??

Plugs don't foul on their own. Why did they foul?
Are they covered with black soot, indicating engine running rich?
Are the covered with oil, indicating oil leaking by the valves or piston rings?
If the car was running OK after the carb rebuild, I would look at the ignition.
You said, you looked at the distributor cap, what about the points and condenser?
Are the points burnt?
Is point gap correct when tested with a feeler gauge?
How old is condenser?
If there is any doubt about performance of points and condenser, I would replace both and properly set point gap.
If you don't do anything but replace the spark plugs, I think you will end up fouling the new spark plugs and not discovering your problem.

 

[darth_linux]

I was gonna suggest timing chain maybe is worn and jumped a tooth, but @CBODY67 already alluded to that.

 

[Big_John]

Plugs don't foul on their own. Why did they foul?

I'll bet that moving it around in the body shop fouled the plugs. Start and move/start and move/start and move... If they were doing that everyday like a lot of shops do, it can foul plugs.