Spark issue help

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notadart

notadart

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Need help reading these plugs/diagnosing a spark issue. I'm a total newb at this, so apologies in advance...

Motor: 360
Plugs: NGK's (brand new)
Wires: MSD (6 months old)
Dizzy: MSD streetfire

Recently tossed on a new intake and dropped in a more aggressive cam. Started up fine, broke the cam in fine. Drove it around and it worked great.

Parked for a week, then took it out for another drive. Noticed a 'ticking' sound from under the hood as I was driving, but nothing major. Car died shortly thereafter, and spent a couple weeks chasing down the issue, which was my starter (uncoated headers right above didn't help). Since then it hasn't run right.

New starter in, starts like a champ, but runs/idles like a bag of smashed assholes.

Got some lovely backfiring through the carb (might have been the ticking sound I heard). Hooked up the timing gun (sorry to say, but it's kinda old, but I think it's accurate) and my timing looks decent.

Pulled the plugs. Thought I noticed wet gas on plug 3. Replaced all plugs.

Ran car again. Plug 1 looks super rich, plug 3 (next one over) looks like it's hardly fired. (see pics)

Wires seem (feel and look) solid. They're only 6 months old custom jobbies. MSD dizzy is 6 months old. No carbon tracking/etc. inside. Connections were all nice and tight, and they were connected in the correct order quadruple checked)

I assume it's something pretty obvious that I'm missing/haven't checked/generally derp'd on. Help please!
 

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Is there any sign of fuel (feel or smell) on that number 3 plug? Assuming you are running a hydraulic flat tappet cam? What rocker arms? And just how much more aggressive is the new cam? I'm asking because that plug looks brand new. Is it possible it's a ignition issue? Yes. But there were a lot of other changes made. Before you can have fire you gotta have fuel. If there's no fuel smell to that plug, I'd personally pull the drivers side valve cover and inspect the valve train. I'm thinking there's something happening there. Whatever you do I would not run that engine until you isolate down more of what's going on, you may do more damage then good. Also the older timing lights do not play well with the MSD systems and your timing may be way off from where it needs to be. Also the fuel fowling on number 1 could be the result of the back firing which could have blown the power valve in the carb depending on what brand it is and how old or new.
 
Strange to me that one plug reads way rich and the other doesn't look like it was ever run. Check basics first, make sure you didn't swap plug wire positions and make sure you have a good connection at both ends of all the wires. What cam did you swap in, and what carb are you using?

If you are in fact a TOTAL newb, you may not already know, your rotor spins clockwise, firing order is 1-8-4-3-6-5-7-2.
http://i.fixya.net/uploads/images/jturcotte_117.gif
 
Dubob said:
Is there any sign of fuel (feel or smell) on that number 3 plug? Assuming you are running a hydraulic flat tappet cam? What rocker arms? And just how much more aggressive is the new cam? I'm asking because that plug looks brand new. Is it possible it's a ignition issue? Yes. But there were a lot of other changes made. Before you can have fire you gotta have fuel. If there's no fuel smell to that plug, I'd personally pull the drivers side valve cover and inspect the valve train. I'm thinking there's something happening there. Whatever you do I would not run that engine until you isolate down more of what's going on, you may do more damage then good. Also the older timing lights do not play well with the MSD systems and your timing may be way off from where it needs to be.
Click to expand...

Correct- hyd. flat tap. Not sure what the rockers are- dude who I bought the cam from had them with it. It's an enginetech cam, and I have the specs written down somewhere. Since I put it in a while ago now, I forget the exact dimensions.
There was a fuel smell to that plug, and it's the one that was wet before. (a little hard to tell, there was a lot of unburnt fuel going on to distinguish the smell).
I agree, it's new timing light time. That said, with the plugs how they are, I'd guess the issue goes beyond timing (and that the intake backfire is due more to unburnt fuel than poor timing)
 
cletus said:
Strange to me that one plug reads way rich and the other doesn't look like it was ever run. Check basics first, make sure you didn't swap plug wire positions and make sure you have a good connection at both ends of all the wires. What cam did you swap in, and what carb are you using?

If you are in fact a TOTAL newb, you may not already know, your rotor spins clockwise, firing order is 1-8-4-3-6-5-7-2.
http://i.fixya.net/uploads/images/jturcotte_117.gif
Click to expand...

RIGHT!?
As I mentioned, plug positions are good, connections are good. Cam is an enginetech (sorry, no specs on me right now) and carb is a holley 650 (4150)

I'm solid on firing order. Not that much of a newb.
 
notadart said:
RIGHT!?
As I mentioned, plug positions are good, connections are good. Cam is an enginetech (sorry, no specs on me right now) and carb is a holley 650 (4150)

I'm solid on firing order. Not that much of a newb.
Click to expand...

Sorry, I missed that part of the original post.

Is it an older Holley with a power valve? Dual plane intake? I have heard that the older Holleys (no personal experience with them) can have a power valve ruined by a backfire through the intake, and that will make it run like "a bag of smashed assholes." (I'm stealing that, it's a good one.) I'm with Dubob, I would want to visually inspect the valve train before spinning the engine any more. If you don't see anything wrong there, watch the movement of the rockers while you spin the engine to make sure you don't have a flat cam lobe or collapsed lifter or something like that going on. A compression test wouldn't hurt.
 
Get busy. Get out the tools

Run a compression check or a leakdown check, or both

Pull the valve gear and inspect the valve gear. Look for parts missing / broke, bent valves, and using air (leakdown) look (listen) for air out exhaust and intake.

Crank engine, watching "valve action" looking for flat lobe(s)
 
If you have a dualplane intake, nos 1 and 3 are on different sides of the carb. the plugs show one side rich and other side dry. Ima guessing the metering block is unhappy.Probably the idle circuit is not right. Could be plugged idle air bleedon the rich side and totally restricted fuel on the lean side. Yeah, Ima guessing.
Spark is easy to check.So get that squared away. The engine does not need to be cranked. Just pull the dizzy out, turn on the power, and hand spin the driveshaft. With the coilwire gapped to ground about 1/2inch, the sparks will fly.Don't start a fire
But since you said it worked great, til it wouldn't start,I'd not be looking into valve covers or timing or compressions just yet. And since you've been cranking, and cranking,and cranking, if it was valve related,the damage is already done.Can't hurt to look tho.
But if something got into the airbleeds, it's pretty easy to get rid of.To blow out the air bleeds, I just remove the idle mixture screws, and those related parts and hit 'em with a couple of little blasts of compressed air. Since the air will be blasting into the float bowls too, don't go crazy.If it does run properly after this, you still need to remove and clean the float bowl, cuz whatever you blew out of the dry side, is still in there.
 
Pulled all the plugs.
1,7,4,6 are black
3,5,2,8 are clean (and don't really smell like fuel)
 

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AJ/FormS said:
1,4,6, and 7 are on the same leg, while 2,3,5 and 8 are on the other leg. Of a dual plane.
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Yup. This puts things back to vacuum leak, intake crack / sealing issues, or carb problem.
 
Cylinder pressures are (low but) similar.
See image.


Carb issue then?
 

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notadart said:
I Googled til my thumbs went numb trying to find that. Thanks. (I suppose I had guessed it)
Click to expand...

You can just look at the intake and follow the intake runners. Basically, it's just every other cylinder in the firing order.

1 {skip 8} 4 (skip 3) 6 (skip 5) 7 (skip 2)

So, 1, 4, 6, 7

What is left is what you skipped,

2, 3, 5, 8
 
Once you fix the carb/vacuum issue, use new plugs to replace the black ones. Plugs that are fouled that bad, may no longer spark. Also consider changing the oil, it might be diluted with gasoline.
 
notadart, something else I was just pondering, and not to take away from anything else because it's all been good, you changed the intake on this engine. If you put an aluminum intake on its possible that the alignment holes in the intake for the dowel pins on the ends are not deep enough for the pins or not there at all.This could allow it to rock one way or the other and prevent one bank from sealing good. Just a thought to keep tucked away. Hope you get it straightened out so you can enjoy it.
 
A/J you're one sharp individual and I'd like to thank you for your insights and contributions here on the forum. Sorry to get off topic, now back to the regularly scheduled program.
 
AJ/FormS said:
So, reading between the lines, Is there now a dualplane, 180* intake, installed on the top of that engine?

The plugs are saying so. But if not, ....IDK
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I'm betting your correct, and that the problem is a carb issue. Certainly looks that way.

To the OP - do you or a friend have a known good carb you can swap onto it to give it a try?
 
cletus said:
I'm betting your correct, and that the problem is a carb issue. Certainly looks that way.

To the OP - do you or a friend have a known good carb you can swap onto it to give it a try?
Click to expand...

1st: thanks for all the help fellas.

2nd. There is an alu dual plane intake on top. You guessed it. I suppose I shoulda posted that earlier. My bad.

3rd: I have a 'good' carb sitting on the passenger side seat. I'll toss it on and test I guess. (Gonna take the holley apart to check the power valve anyway... seems like a worthwhile project. I should research jet and squirter sizes while I'm at it)

4th:
Thanks for the thoughts, re:
" If you put an aluminum intake on its possible that the alignment holes in the intake for the dowel pins on the ends are not deep enough for the pins or not there at all.This could allow it to rock one way or the other and prevent one bank from sealing good. Just a thought to keep tucked away. Hope you get it straightened out so you can enjoy it."

-will look into that. God I really don't wanna take my intake off though, that's a *****.
 
notadart said:
1st: thanks for all the help fellas.

2nd. There is an alu dual plane intake on top. You guessed it. I suppose I shoulda posted that earlier. My bad.

3rd: I have a 'good' carb sitting on the passenger side seat. I'll toss it on and test I guess. (Gonna take the holley apart to check the power valve anyway... seems like a worthwhile project. I should research jet and squirter sizes while I'm at it)

4th:
Thanks for the thoughts, re:
" If you put an aluminum intake on its possible that the alignment holes in the intake for the dowel pins on the ends are not deep enough for the pins or not there at all.This could allow it to rock one way or the other and prevent one bank from sealing good. Just a thought to keep tucked away. Hope you get it straightened out so you can enjoy it."

-will look into that. God I really don't wanna take my intake off though, that's a *****.
Click to expand...

At this point I doubt you will have to pull the intake. Good luck!
 
So my power valve definitely looks like it was damaged, and there's some dirt and crap around it. See pic.

Will clean and get a new power valve.

Anyone want to explain how that could have been causing my issues?
 

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If the cavity in the mainbody was dry then the PV is likely fine. When the PV goes bad(gets ruptured), or the PV is not tight, or the wrong gasket is installed, fuel passes through or around it, into the cavity, and down into the plenum;overfueling the engine under most operating conditions.
The metering block on the right is where I suspect the problems are.Unscrew everything,clean out the circuits, paying particular attention to the low-speed circuit and emulsion tubes. Blow out the delivery passages in the main body. Prove all circuits are open with an aerosol cleaner: DO NOT get that stuff in your eyes; it burns Mommy, it burns. Prove the circuits!
No idea how that gunk got in there:(
 
AJ/FormS said:
If the cavity in the mainbody was dry then the PV is likely fine. When the PV goes bad(gets ruptured) fuel passes through it, into the cavity, and down into the plenum;overfueling the engine under most operatind conditions..
Click to expand...
Well, it was dry... just dirty.
All jets are clear. Carb looks fine otherwise. Anything else I should be looking for?
 
"all jets are clear" is not a complete answer.
A complete answer might look like this;
I found crud in the bottom of the idle wells, but all of the emulsion holes were open. The driver's side delivery passage was gummed up.I had to remove the brass cup plugs to get the crud out, How do I reseal those?
 
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