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

 

[PoliceMonkey161]

My guess is you have a valve problem. Possibly as minor as carbon build up around an exhaust valve? But could be more involved.

 

[Turbogus]

Thanks PM161 going to do more diagnostics as I get time. However if it were a valve problem would it be so intermittent? What I mean is this single spit only happens at the most once per day, yesterday not at all.

 

[PoliceMonkey161]

It could be something intermittely holding a valve open. If you're above idle, throttle plates open, something is reverbarating backup the air/fuel column within a runner. And it's hot enongh to iginite the runner and plenium. Since your exhaust note/tone has changed, problebly exhaust valve. But thats not a definitive answer, just thinking through this.

 

[Catoctin Jeep]

Put your new plugs in and go out and run it like you normally do. Pull the plugs and take a look at them. They all should be a light tan color. If one or two are white and blistered looking you may have a lean condition. Not sure what carb your running, check for any leaks around the base gasket and vacuum hoses.

 

[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.

 

[JPNinPA]

My guess is you have a valve problem. Possibly as minor as carbon build up around an exhaust valve? But could be more involved.

The carbon buildup is a common issue . Running the engine above 3300 rpm for a while helps rotate the valves and avoid buildup. The water mentioned also works to release buildup. It works like sea foam you run it let steam build up, shut it down let it sit and run it hard after to break down the carbon.

 

[Turbogus]

Thanks JPNinPA, if I do this again I'll keep this in mind.

 

[flatie46]

Turbogus glad ya got Black Betty lined out, also glad I'm not the only one in the world driving a CJ5 as a DD. Though I do cheat every now and then with an 82 Scrambler. Anyway good luck with it.

 

[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*

 

[JPNinPA]

Do you have a catalytic converter? Is getting clogged?

 

[Turbogus]

No Cat on this old CJ JPN, after checking the timing last night (13*) I rolled it back to 6* (within spec) The carb is a Carter AFB that I kitted and tuned down (smaller jets and one step up stiffer metering rod springs) from an LT1 I had it on several years ago. I'm starting to lean towards an exhast valve issue.

 

[Turbogus]

Well, went to work today and not a peep of misfire out of the motor, thank Heavens!

This could be due to finding a little corrosion on the coil terminals and finding the timing issue may have done it... time will tell.

 

[Jordan_Roberts]

Ok that is good theing **** your self

 

[Bond--007]

Everyone wave hi to the troll ^^^^^^ :spank:

 

[Turbogus]

:agree:

 

[Tison78_CJ5]

When mine spits, I just spit back..

 

[PoliceMonkey161]

How is your Jeep running?

 

[Tison78_CJ5]

Mine is no change. The parts are still at the balance shop.
I have bought all the parts, and just waiting to get everything together.
I did call the shop yesterday. Told him I would be down there to pick up my parts on Monday, ready or not..
This has gone on ay too long.
I cold just spit....
Tison

 

[Turbogus]

...if my Jeep is ever running I'd better go and catch it