Motor 'spits' once in a while

[Turbogus]

Well, a couple of weeks back I went and visited my good friend Craig formerly of the late great Macs Jeeparts (We lost a 'beard of knowledge' God Bless you Mac) a couple of years ago.
Anyway, Craig had to move up the Freeway to Jefferson and on the way back Black Betty ('78 CJ5 ) was getting pushed by maniacal traffic on I-5. In the process I broke loose some carbon and closed the gap on one of my plugs, shorting it out and causing a miss, with that the exhaust tune changed and I changed out all of the plugs. This took care of the miss, but now I have a new issue. Randomly and only once or twice in my 12 mile commute the motor (AMC 360) 'spits', (like a small backfire through the carburator) note that this is random and normally only once a day. The exhaust note has not yet returned. This occurs when the motor is at operating temp and cruising on the Highway, this 'spit' has yet to occur during slower, stop and go city driving.
Since, I've run a tank of Premium fuel through her and reved up the rpm's shifting at 3800 rather than my usual 3000.
I'm leaning toward a fuel issue and if I have time I'm going to check my fuel connections tonight, and perhaps change out the fuel filter - one of the few items I have'nt touched since first buying 'BB'.

I welcome any other opinions as after my 11 hour work day my mind is on wind down and I'm zombie'n pretty hard.

Thanks and a lift of the lynch lid.
Gus

 

[Torxhead]

Gus, I will start out with guessing at a possible ignition control module failing. Providing you have the Motorcraft ignition. Other symptoms will include the icm getting warm to the touch and the ignition missing getting worse especially after engine warmup. If it were the carb, I would think that the spark plugs would be reading on the rich side.

 

[Lumpy Grits]

What plugs did ya put in?
When was the last time you changed the dizzy cap, rotor and wires?
When did you last ck the ign. timing and vacuum.
When did you last change the fuel filter?
LG

 

[Turbogus]

What plugs did ya put in? Autolite 65 .37 gap
When was the last time you changed the dizzy cap, rotor and wires? Sep 2013 Standard cap FD 149 rotor Blue Streak FD 311X, wires Standard 7843
When did you last ck the ign. timing and vacuum. 18 Sep 14
When did you last change the fuel filter? Not yet as mentioned in my first post.

 

[Turbogus]

Thanks Torxhead, The Ford ICM could very well be it, I had a Mopar ICM on my '77 I had years ago but it outright failed without any indication that it was on it's way.

 

[Torxhead]

Come to think of it, a bad pick up coil in the distributor can affect the ignition also. Of the three wires that come out of the distributor, the violet and orange wires are connected to it. There should be 400-800 ohms between those two wires. The remaining black wire is the ground for the icm which would be better served connecting it to the battery negative.

 

[GARGOYLEJEEPER]

Turbogus,
Sorry about your problem, if you come visit again I will tell you what it is.
Did it wake up your rider? That section from the paper mill to the first off ramp is where every one wrecks, because we need another lane, Albany and Linn County has paid the State/Feds the money and waiting for them to get started (2016).
I will tell you anyway if you had a Holley I would say power valve, but you do not so I will say it is your accelerator pump having a discharge.
Anything else you will have other symptoms.
Your Carb needs Repaired.

 

[Turbogus]

Thanks Craig, if it is the Carter AFB rather than electrical. The odd thing is this single spit only happens at the most once per day, yesterday not at all.

 

[Turbogus]

Well today at work I slowly ran a little over a pint of water down the primaries (not much smoke at all) and ran her out on the Highway and the "pock snapple khrap" that I was accustomed to returned and not one 'spit', 'blip' or 'belch' came through. I'll rap it out on my commute home tonight but I think I'm on top of it now.

 

[GARGOYLEJEEPER]

I blame it all on unleaded methanol, That and OR humidity, damn temperate rainforest.
Hopefully no carb rebuild.

 

[Torxhead]

A can of BK 44g is a safe way to get the carbon out, if thats what you think the problem is.

 

[Turbogus]

Thanks Craig, that AFB is only a few years post rekitted/rebuild, but 'BB' seems to be alright now-way better than last week.

 

[GARGOYLEJEEPER]

Every spring I fill up my truck with premium and dump a bottle of Injector cleaner, high octane and water displacer in to help in cleaning the inside. Since I spent $2,500 rebuilding it, I do not want to ruin it.

I am glad it is not raining.

 

[Turbogus]

Well nutz, the spitting and off exhaust note had returned but, I recall when I was chasing an overheating gremlin a couple of years ago I seem to remember retarding the timing some, going to try to find my light tonight and put 'er back to 10*

 

[GARGOYLEJEEPER]

What is your timing at now?

 

[Turbogus]

Went blind looking for my timing light that's been MIA since the move. Broke down and bought a new one at the NAPA bucket sale yesterday, also got a new coil cap as the wires on the positive side were exposed and down to only a few strands. In the process of rewiring with 12 gauge and those Hella connectors I got for my fan upgrade.

Went blind again trying to find the timing tab. It's been many a moon since I've timed an AMC. The timing mark is different than the Chevys I'd become accustomed to. By the book it looks to be at 10 o'clock on the timing cover, going to try and find it again tonight.

 

[Torxhead]

While you have that coil cap off you could check the coil for 1.35 ohms.

 

[Turbogus]

Good to know Torxhead, thanks!

 

[Turbogus]

So it turns out the timing was at 13* advanced, rolled it back to 6* (within spec) I'm beginning to think something else is at play here.
Going to pull a few plugs tonight and see what they have to tell me.

 

[Turbogus]

I only got one of the plugs out before the dinner bell clanged (#1) and it looked perfect but that small amount of corrosion that I found on the coil the terminals that I addressed with a wire toothbrush and dielectric grease may have been the issue.
That is if todays' commute is any indication, not a peep of a misfire today.