Spark plug diagnosing help, please!

[moparedtn]

I tried the Autolite racing plug,I use a regular NGK for $20 a set.

Well, we're in East BF here, so I settled for a good old set of Autolite coppers #85.
Went in fine, used some dielectric grease on the boots to make sure I was seating them all the way (no mean feat with these #$%#@$% Hedman headers), checked over everything I could think of visually.
Double-checked wiring through the firewall next to the new flex line for the oil pressure gauge to make sure I didn't ground something accidentally.
Then I hit it.
Started easy and ran without protest. I could get out of the car within the minute, since it idled by itself like it usually does (no choke, so that's pretty cool).
I let it run a bit to warm up at the higher idle I had to set it at last time to keep it running; I ran the timing light around all 8 wires to check for strobing, which turned out ok.
After about 5 minutes of this and that, I grabbed a flat blade and backed the idle back down to its' normal 800RPM, where it sat fine without protest.
Goosed it a few times over 3000RPM gingerly; no fuss.
Put the !$^%&$^ air cleaner back on it, shut the hood and called it a day,
Sheesh.
I reckon a road test will confirm, but it acts normally again.
I have no idea what I did to "fix" it.
None whatsoever.

 

[moparedtn]

Adjust the valves again.If a lobe is going,you'll have alotta adjustment on that rocker.

B-b-but these ain't adjustable!
*snicker*
Yes, I know. That's how I found out the last cam got wiped - went down the bank of rockers and wouldn't ya know - a couple were slap-happy loose.

 

[moparedtn]

Are you pretty certain you have an electrical problem? It could be a fuel related issue especially since the car hasn't been driven much. This could be as simple as a fuel filter and/or clean out of the carb. Depending on your carb some have a filter or screen inside the fuel line connection that could be clogged. If not then a check of the pump could be in order. Going back to electrical, since you have el ig is issue as mentioned is a check of the rotor and air gap. You can run a vacuum check if not done as another way to trace down problem. Also I ran into ECU problem on my '63...crapped out just like that after doing all sorts of checks before zeroing in on it. Just a few more cents to toss at you...

Well sir, it does get driven at least weekly. Entire fuel system is new, including filter, "hemi" fuel pump and Edelbrock AVS, which I just pulled the top off of just to make sure. Spotless.
Yep, just had the cap off. Accel brown heavy one w/rotor, just like the good old days. Looked fine.
Interesting you mention the ECU - I still have the new "store bought" one on there, but I also have a Mopar orange box one ready in the wings. It was next up for trying, should todays' efforts prove fruitless.
Excellent point on the vacuum. I shoulda thought of that. I know what it should read (it does really well usually, around 15-16Hg). Also next up if todays' effort prove futile.
Thanks!!

 

[moparedtn]

I was going to say the same thing. I like to pull the valve cover and turn the idle down about as far as you can without it stalling to look at the valves opening and closing. Make sure you cover up with a towel or something like that because some oil will be thrown around. You'll know right away if one of the lobes is wiped.

Also, when I've wiped a lobe before, especially an exhaust lobe, the engine would get pretty hot pretty fast when not moving, so that's something to look for as well. But judging by the plug color, they are all firing somewhat evenly.

Thanks for replying.
Temperature was one thing I was paying very close attention to when things went south the other day, in fact. I was thinking the same thing about the exhaust lobes.
This rascal runs pretty cool (idles at 180F all day) and didn't jump up the other night until I had a "rev fest" after it started goofing up and I started goosing hell out of it. It pushed towards 190F then.

I dunno, man. I have no idea what I could have done to "cure" it today.
Well, not ready to claim a cure yet, either. Road test first.
Maybe a plug wire was just starting to come loose or was getting too close to a header or or or....
Oy.
Somebody send me a good old 440 out of a motor home.

 

[mopar 3 B]

Did you ever check that Champion #6 plug to see if it fired?

 

[moparedtn]

Did you ever check that Champion #6 plug to see if it fired?

It's hitting on all 8 now. Beats me.
I did the deal with the timing light on all plug wires too. All nice and bright.
It might just be that particular Champion failed internally??

 

[mopar 3 B]

It's hitting on all 8 now. Beats me.
I did the deal with the timing light on all plug wires too. All nice and bright.
It might just be that particular Champion failed internally??

15 years ago it was not uncommon. That is when I quite using all but their copper core truck plugs.

 

[Cranky]

One or more lifters pumped up when you wound it up? How much rpm did you take it to the first time? Had a 318 (seems like I can't get away from them thangs!) start running a bit rough during a radiator flush so I revved it up kinda high after a couple of easy revs didn't smooth it out and the thing died and wouldn't restart. Had me scratching my butt after awhile so I dropped the hood and after I came back to it a couple of days later it fired right up. My first engine that I built would also pump up a couple of lifters after taking it up kinda high. It would smooth out after a bit but before long, it got worse as time went on. Replaced them with better lifters and that problem went away. I like it when things fixed themselves but it always makes me wonder just what it was that caused the problem in the first place lol

 

[moparedtn]

One or more lifters pumped up when you wound it up? How much rpm did you take it to the first time? Had a 318 (seems like I can't get away from them thangs!) start running a bit rough during a radiator flush so I revved it up kinda high after a couple of easy revs didn't smooth it out and the thing died and wouldn't restart. Had me scratching my butt after awhile so I dropped the hood and after I came back to it a couple of days later it fired right up. My first engine that I built would also pump up a couple of lifters after taking it up kinda high. It would smooth out after a bit but before long, it got worse as time went on. Replaced them with better lifters and that problem went away. I like it when things fixed themselves but it always makes me wonder just what it was that caused the problem in the first place lol

Hiya Cranky!
Oh, I don't get carried away with it.
Too skeered the thing is gonna grenade.
When it pulled that whole rough running/wouldn't idle bit, I'll admit to a bit of frustration. Buzzed it up past 4k, then past 4500, then past 5k to no avail. I've never pushed it towards 6000RPM ever - even pi$$ed off, I ain't that crazy.

Dang brand-new Comp Cams cam and lifters. Best not be misbehaving like you describe.

 

[Cranky]

I didn't buzz the teen up much either I didn't think but with it's age and mileage, I'm sure 4000 was about it's limits with tired springs etc lol. These little engines have surprised me over the years with what they will do with a decent valve train etc.

 

[moparedtn]

I didn't buzz the teen up much either I didn't think but with it's age and mileage, I'm sure 4000 was about it's limits with tired springs etc lol. These little engines have surprised me over the years with what they will do with a decent valve train etc.

I'll have to get me an engine with one of them thar decent valve trains one of these days.
Until then, this whatyamacallit motor will have to suffice.
Budget is tee-totally shot.

 

[moparedtn]

Update 8/12/16:
With new plugs in it, I took it to the local cruise-in this evening.
It fired right up and seemed ok, so off I went. It ran fine for the first few miles...
then as I approached town, it started misbehaving again and wouldn't hold an idle.

It sounds like it's dropping a cylinder or two, only those cylinders "hit" every so often.
Needless to say, I'm stumped and depressed now.
I guess that's the end of enjoying the car and I probably need another engine.

 

[Ron H]

Is the "miss" you mention steady or more sporadic? If you put a vacuum gauge on finding a bouncy needle it could be a vac leak or worse a valve issue. One trick is to run a little penetrating oil into the carb while its running to see if this steadies the vacuum. This is to possibly diagnose a bad or burnt valve or worn guide. If real lucky running Sea Foam through the motor can remove carbon deposits if this condition isn't too bad. Also a compression check would likely be in order if you haven't done this. OK, I'm just tossing out some straws for more exploration here though as the issue remains mysterious with your description of running fine then all of a sudden not. As a motor warms up there is obviously a change from heat expansion affecting valve guides, rings, bearings, etc.

 

[Darthomas]

Sea Foam in the oil can remove varnish from a sticking valve stem.
A sticking valve will also do what you describe.

 

[moparedtn]

Is the "miss" you mention steady or more sporadic? If you put a vacuum gauge on finding a bouncy needle it could be a vac leak or worse a valve issue. One trick is to run a little penetrating oil into the carb while its running to see if this steadies the vacuum. This is to possibly diagnose a bad or burnt valve or worn guide. If real lucky running Sea Foam through the motor can remove carbon deposits if this condition isn't too bad. Also a compression check would likely be in order if you haven't done this. OK, I'm just tossing out some straws for more exploration here though as the issue remains mysterious with your description of running fine then all of a sudden not. As a motor warms up there is obviously a change from heat expansion affecting valve guides, rings, bearings, etc.

Sea Foam in the oil can remove varnish from a sticking valve stem.
A sticking valve will also do what you describe.

Lord knows, fellas. I call this engine the "mystery motor" because I wasn't involved in its' construction at all; the engine literally was handed to me as is.
The story was that it was rebuilt by the previous (now deceased) owner, but it's just that - heresay.
I have run compression on it (an almost eerie 130psi across the board, with no more than a couple psi variance between cylinders).
Oil pressure is certainly good enough, at over 50psi cold/30 psi hot idle.
Fuel and ignition systems have all been entirely replaced.
The cam was replaced by myself after this engine wiped a couple lobes on the previous one, something I attributed to the mistaken use of full synthetic oil in a supposedly "new" engine - I corrected that with the use of a superior quality, high zinc oil used along with proper break-in oil from Comp Cams.

I got the thing running halfway decently with time and all was well until recently, when I installed a mechanical oil pressure gauge.
Coincidence? I sure hope so, can't see any reason for that to have caused issues.

It's a pretty constant "miss" now; it cleared momentarily with the replacement of the plugs, but came back pretty quickly once underway and warmed up and didn't leave afterwards.
There is certainly some mechanical noise coming from the motor; I don't know any better, but it always sounded around 2500rpm or so like a rod noise.
As it is now, it won't idle for squat, so I had to turn up the idle screw just to keep it running at stops - but when I'm underway, I can hammer the thing and it will still sort of take off, even do brief burnouts - but that "warble"/miss is constant.

I just picked up both Marvel Mystery oil (I saw that stuff free up a burnt valve on a later-model Ram that had overheated, like a miracle cure) as well as Sea Foam.
The plan is to introduce the Marvel into the oil while simultaneously doing the "Sea Foam treatment" - getting the engine to suck up the can of Sea Foam directly into the intake as rapidly as possible, then shutting it down to let things "soak" and firing the engine back up later on for the smoke show.

Appreciate all the advice. Hope this does anything at all, for I am surely out of time and money on her. It would be a shame to not see this though before I'm gone. Time is one thing I don't have a lot of anymore. :-(

 

[moparedtn]

Update:
Hooked up a vacuum gauge and started it cold.
It's now doing the warbling deal even when cold.
Vacuum gauge is reading around 13.5hg. It dances a little bit, not much, maybe a half pound either way at most. Twitching rather than pulsing like a burnt valve would cause, if that makes any sense.
More like a vacuum leak?
I took a can of Brakekleen and started spraying around the intake gasket and carb base areas. When I got to the area of the intake over cylinders 6 & 8, it jumped some and vacuum went up to 15hg - and it was repeatable.

Hmmm, vacuum leak perhaps?

To test the vacuum leak theory, I then tried running out the idle mixture screws a full turn more rich and sure enough, it responded a little when I did.
Went over all the intake bolts and carb base bolts, tightened the carb air horn screws and the plug in the rear of the Edelbrock carb.
Fired it back up and vacuum was almost 14hg, but the warble was still there, only less so.

You know, I don't really hear out and out mis-firing, popping out the exhaust, just a very noticeable roughness.
I was able to drop down the idle speed screw on the carb a little more and it would hold a (rough) idle at 800rpm - but as I looked inside the car to see what idle speed I had, I notice the temperature gauge was WAY up on both factory gauge and my aftermarket electric one, over 210 degrees!
I've never seen it run anywhere near there before, ever.
Jumped in it and held engine speed up around 2000rpm and hoped the temps would return to normal, which they eventually did.
What the hell was that all about? The car hadn't even run 10 minutes yet.

I figured I couldn't tighten anything anymore than I already had without breaking something, so I grabbed the can of Sea Foam and the PCV hose and went to work, making it suck the entire can up through the intake.
Lots of smoke, of course.
Shut it down immediately once the can was empty to "soak".
Lost my damn PCV valve somewhere in the process.

That's where I am right now. Anyone got any ideas?
Is this thing trying to pop a head gasket on me?

 

[moparedtn]

Update of update:
Seafoam all blown out. Very little difference.
Whatever happened all at once when I was revving it when I installed the oil pressure gauge is still there.
At a loss what to try next.

 

[hangn0ut]

Next you put new intake gaskets on. Tighten to specs. Dont just crank on em. Should take about 45 minutes.

 

[moparedtn]

Next you put new intake gaskets on. Tighten to specs. Dont just crank on em. Should take about 45 minutes.

Thanks for replying.
I'm thinking what you're thinking at this point, but what the hell do I know?
Since this engine is a mystery to me and the factory intake on it is one I picked up at a swap meet some years ago, heck, the heads may have been milled and I have a lousy seal between them and the intake. It just has a Permatex'ed bathtub gasket on it right now.
Reckon I'll fetch one that has the organic gaskets already made onto both sides.

I just changed the oil (which only has a few hundred miles on it). Oil came out quite dark and the magnetic drain plug had the usual gray bearing material "sludge" on it - not a lot, but enough to catch my attention.
I refilled using the Driven high-zinc oil and added about 20 oz. of Marvel Mystery oil to it to finish. Ran it a few minutes and, although the motor seemed a little "freer", the problem persists.
There is a pronounced "thump" to the idle that sounds almost like a cylinder dropping - very pronounced difference in the sound from before when all was well.
If you give her the beans, once she's over 4000rpm she starts flat-out missing. Lots of pops on deceleration, too.

I have a demonstration video uploading to YouTube right now. I'll post it soon as it's ready.

 

[moparedtn]

Video is up. You'll hear that pronounced, constant "thumping" and see the erratic way it takes off on its' own with me holding my foot still on the accelerator.