318 Poly Issues after Sitting all summer

threewood

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1962 Ply with a 318 Poly 4 bbl Edelbrock 1405, headers.

The car sat longer than it should have without being ran. Less than half tank of gas. Started it up, idles rough, wants to stall. Drove it a bit and when accelerating it was backfiring and popping through exhaust. It can get up to speed slowly. If I try and get on it it will pop and backfire.

Filled the tank up with fresh fuel. Checked carb out and ran a wire through orgunned. Was not varnished inside. Fuel filter not clogged. Floats not stuck. Needle valves not stuck. I didn't check the accelerator pump for a shot. I did not look at check balls. Ran it for 6 miles.

Idles better but still pops and backfires on acceleration. I can remove each a/f needle which creates a vacuum and high idle until I screw them back in.

1. Could still be bad gas in the mix
2. Check valves stuck / shooter not shooting / carb still gunked.
3. Longshot but could a stuck mechanical advance cause it?

It did this last year and fresh gas fixed it up. I had 50 minutes today to play with it so not a lot of time to troubleshoot. What do you think I need to look at?
 

Ron H

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Did you have decent gas in the tank? I run, at least half the time or more, ethanol-free premium gas in my built poly. Have to drive 30 miles to get it where I am. If I follow, you checked to find the jets a squirting nice looking down the carb? If not, sure you know the next back checks. You could check the timing. My guess is run a fuel cleaner through the system as a start..
 

Ron H

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Another thought - electronic or stock ignition? If latter, I'd check the points for any indication of corrosion and gap setting or if electronic (I have an earlier mopar elec system) as part of the timing check; the reluctor and gap setting. More remote; but since you say you had this issue before and running it fixed it, a fuel cleaner like seafoam down the carb and some in the tank might do ya.
 

Darter6

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Sticky valve/guides might be my guess. A friend just bought a 37 Dodge pickup and said it cleared up with a quart of Marvel Mystery Oil added to the crank case.After about a hour of run time it cleared right up. JUST a guess.
 

tonysrt

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I bought a 70 Dart that was sitting for several years. Put a new filter in it ran it and breaking up at high speed. Put another new filter in, previous one clogged up, and after few miles same problem. I then replaced the tank with a new one and solved that problem. Idle was ok but couldn't supply enough fuel when driving at speed.
 

ruffcut

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If its ethanol gas, I'd say clean the carb, after sitting a long time that's probably it.
 

PurpleBeeper

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All of the tihngs listed "might" be the problem....but I'm going with your first guess.... BAD GAS. Drain that tank completey & put some fresh premium in there and you're good. Just in case you got a lot of water in the tank (condensation?), you could throw in a bottle of Heet too (red bottles work better). You said it yourself.....did the same thing before and the fresh fuel fixed it
 

Billccm

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Berrymans B12 and drive it.
 

threewood

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All good suggestions. I'll get a chance to mess with it tomorrow.
 

threewood

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Gas in tank is 91 ethanol blend. No straight gas here unless I use race fuel.
 

Billccm

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Gas in tank is 91 ethanol blend. No straight gas here unless I use race fuel.
I've been putting 2 ounces of StaBil360 Ethanol "Stabilizer" in every fill up. This was recommended by the previous owner of my Road Runner. It might be snake oil, but I sleep better at night.
I have also been using 2 gallons of racing fuel per 5 gallons of 91 E10 and this has been an improvement.
I have a dead spot in my throttle that seems to have been cured by a bottle of Berrymans B12. I have seen Vice Grip on YouTube use Berrymans in cars that have sit for >10 years with good results, and now keep a few bottles in the garage as 6 month maintenance kind of things.
 

Sixpactogo

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IMO.......it was the ethanol blend that is causing the grief. The alcohol eats up the accelerator pump. Been there done that. I don't run that shit in anything with a carburetor. We still have the Premium 91 with no ethanol around here. $.50 higher in price but have not had an issue with any of my carburetors sitting idle for as long as 6 months but I add StaBil when I put them away for the winter. Someone told me that the new carb kits have updated accelerator pump material that holds up better to the alcohol. Probably what you need.
 

threewood

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IMO.......it was the ethanol blend that is causing the grief. The alcohol eats up the accelerator pump. Been there done that. I don't run that shit in anything with a carburetor. We still have the Premium 91 with no ethanol around here. $.50 higher in price but have not had an issue with any of my carburetors sitting idle for as long as 6 months but I add StaBil when I put them away for the winter. Someone told me that the new carb kits have updated accelerator pump material that holds up better to the alcohol. Probably what you need.

They do. The one in the car is the new
type. I need to see if it is pumping a fuel shot though.
 

Sixpactogo

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The Accelerator pump in my 60 Dart 318 had a new kit too but after not even a full tank of the Ethanol garbage it started doing what you describe. When I took the top of the carb off, I noticed the pump gasket was already hard, shriveled up and even missing a small chunk.
 

Ron H

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Sticky valve/guides might be my guess. A friend just bought a 37 Dodge pickup and said it cleared up with a quart of Marvel Mystery Oil added to the crank case.After about a hour of run time it cleared right up. JUST a guess.
I've used this stuff for years...its been around since the Dead Sea was still sick. I've had good results using it.
 

threewood

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Update: Fixed.

Accelerator pump was not shooting. Cause was a stuck check ball under the squirters. I went through and probed all orifice holes with a piece of welding wire. I added a can of Sta-Bil 360 (its what I had in the garage).and took it for a spin.

Ran better right out of the gate, a bit of popping but it cleared up a few miles into driving. No issues wot or driving around town.

Stuck check valve + nasty gas was the culprit.
 

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