1965 352V8 very rough idle with back fires

[Himi52]

The truck was running fine going to the store. It started running a little rough. I came back home going on the side streets and it quit several times but started right up. I started it up couple days later and it was very rough and at a high idle it backfired several times. Think it could be a timing issue? Had the carburetor rebuilt. New plugs and wires. Thanks for your help

[fordor41]

maybe timing chain jumped a tooth. also check PCV valve.. If stuck in open position you'll get low vac and noisy exhaust

[ponymare]

First check the points for the correct gap, and being clean, check the cap for cracks, and make sure the carbon button in the center is touching the rotor cap spring.

[darrell]

if it was running good when you shut it of then started acting up when you next started it it probably jumped a tooth but check all of the above first.

[58Yeoman]

One other thing to check is the bottom of the distributor for wear where the oil pump rod goes into the bottom. Mine was so worn out that it barely turned the oil pump resulting in low oil pressure.

[KULTULZ]

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I started it up couple days later and it was very rough and at a high idle it backfired several times.

Was the high idle possibly the choke fast idle? If just a high idle with the choke open I would suspect a vacuum leak. Use a vacuum gauge for diagnostics.

Any excessive fuel smell as with a flooded carb?

Spark strength?

[Crankster]

Defective ignition condensers are a likely culprit here. Unless they can be tested at high voltage, there's no way to know for sure. But any of the el-cheapo no name condensers from you know where are failures waiting to happen.

[Marcus]

Himi52: Just a thought: does your carb (I know you indicated rebuilt, but still) have a fuel filter, either in-line or in the carb body? I've had several instances whereby the symptoms are exactly as you describe, and the filter was the culprit.

[rotorwrench]

Backfire through the carburetor is an indication of a lean condition which seems to fit with the rough idle. It could be blockage in the idle circuit. A fuel pressure checkwill see if the pump isn't up to snuff.

A bad timing gear train can be checked by following a procedure for a valve timing check. If an exhaust valve is opening to early then there can be afterfire in the exhaust. If it gets that bad the it should show up on a compression check.

Intermittent ignition problems could be a bad condenser. The points condition will suffer in this case. I had a loose upper distributor bushing that would cause an intermittent miss but it didn't do it all the time. Just enough to bug you.

[Gene F]

Vaccum leak maybe????

[wbedwards]

My car did that from loose connections on the ballast resistor. Ended up soldering them to stop it. Blew my muffler open.

[KULTULZ]

Why one buys off-shore junk I will never figure out.

POINTS (DP-12) (1957-1974 V8) and COND (DC-13-A) (1959-1974 V8) are still available from FORD (MOTORCRAFT).

Better yet, a PERTRONIX II install will get rid of all that ancient history headaches.

[bobss396]

Condensers fail suddenly. If you have the last one you took out, try putting that back in. With points cars, I always saved the points and condenser set for emergencies on the road.

[craig]

Something not mentioned is the small ground wire on the breaker plate. Sometimes the end will break and appear to be still connected. When the vac advance moves the breaker plate, the wire seperates...no ground.

Another possibility is the breaker plate itself. In the early 70's motorcraft was marketing a replacement breaker plate assy., it was designed to twist for the advance, but also slide slightly so as to have less dwell change. Was a slick idea, but when they wore out, and they did early on, the dwell changed drastically, the points would nearly close up.

As far as condensors, I learned in the 60's that when you replaced the points, and they weren't totally pitted or burned up, that you reused the condensor. I drove a '56 Ford wagon for 10 years and 90K miles with the same condensor, real US made.

[frnkeore]

I agree with the info on the condenser. Change it out with a new American made.

Regarding jumping timing, in the years I was a mechanic, I found that if the timing chain, jumped 1 tooth, it would be hard to start and would spin easily but, be hard to get started and loose power, if it jumped a second time, it wouldn't start.

[rotorwrench]

I'm not sure how many are American made now days unless that includes Mexico.

[scicala]

I guess we're just talking to ourselves again, since Himi52 hasn't replied since he first asked for suggestions.

Sal

[Himi52]

Hi,
Thanks for all your suggestions. I took out the gas tank and leaned it out. I got about a cup of rust from the inside. I recently tried to start it with no luck. It sputtered and it won’t stay running. I changed the fuel pump, coil, distributor cap and rotor, points and condenser. I will try replacing the condenser and points. I will stop by the local Ford dealership and purchase the parts there and see what happens. With the 2100 carb is there a filter in the carb? I have three filters including the one in the fuel pump. Sorry for the slow response. Hopefully I can get it started and and be able to drive it.

[dmsfrr]

Originally Posted by Himi52

... is there a filter in the carb? ...

There might be? Not very familiar with that carb. But earlier ones had a small screen filter just inside the inlet fitting. If they're unnoticed for quite a while they of course can be clogged.
.n

[KULTULZ]

Originally Posted by Himi52

I took out the gas tank and leaned it out. I got about a cup of rust from the inside. I recently tried to start it with no luck. It sputtered and it won’t stay running. I changed the fuel pump, coil, distributor cap and rotor, points and condenser. I will try replacing the condenser and points. I will stop by the local Ford dealership and purchase the parts there and see what happens.

With the 2100 carb is there a filter in the carb? I have three filters including the one in the fuel pump.

Did you just flush the tank or had it professionally done?

Exactly where are the three filters? Would you be comfortable removing the carb top plate to see if any debris is sitting in the fuel bowl? Sounds to me the carb is fouled.