Extra Sparks?

[jgknowla1]

OK, I think I've done enough research and troubleshooting now to know what to even ask. Here's what's going on:

I've got an '82 C10 with 305/350 and quadrajet. It has HEI and ESC.

Yesterday it started idling rough - sort of surging, but would be fine with any amount of throttle. No tach in the truck, but the oil pressure would move with the surges.

By tonight it's gotten worse to where it's rough/low RPM and shaking more often than not while idling.

I went though it looking for vacuum leaks and capping off ports, but that didn't help.

I put the timing light on it tonight and the timing seems fine, except that there seem to be "extra" sparks. If "X" represents a flash of the light, here's what I SHOULD see:

X.......X.......X.......X.......X.......X.......X.......

here's what I AM seeing though:

X.......XXX.....X.......XXXXX..XX.......

There are still spells of what looks like normal timing, but I swear that during the times of "extra sparks" is when the RPM drops and the engine shakes.

So. My question is - does this sound like it's the ignition module going bad? It doesn't seem to be related at all to engine temperature.

Any ideas?

[68longhorn]

unplug the 4 pin connector coming from the dizzy and jump pins a and c (I believe) together on the dizzy side.

[jgknowla1]

Originally Posted by 68longhorn

unplug the 4 pin connector coming from the dizzy and jump pins a and c (I believe) together on the dizzy side.

Hey 68longhorn, thanks for the reply.
I've thought about doing that trick before just to get the ESC out of the way. But, the question I always come back to is about spark advance. I don't have a vacuum can on the distributor, and I don't have mechanical advance inside. I figured the ESC was controlling advance from its vacuum input on the firewall.

If I disable the ESC with the connector mod, wouldn't that do away with all my spark advance? Maybe I don't understand what exactly this mod does to the ESC.

[irishman999]

No sir, your esc does not advance the timing, it only retards it. To my best understanding of the system there is a knock sensor in the passenger side of your motor threaded into the block. That sends a signal to the Esc when it detects early detonation (pinging) and the ESC box will turn back your timing some how. Your distributor should still have the vacuum advance line plugged into the carb. Hope this helps.

[68longhorn]

You don't have to disable it forever, just temporarily jump it and see how it goes.

[jgknowla1]

Originally Posted by 68longhorn

unplug the 4 pin connector coming from the dizzy and jump pins a and c (I believe) together on the dizzy side.

Hey 68longhorn,
I got a chance to try what you said tonight. I found the 4-pin connector that goes from firewall to dizzy and unplugged it. On the dizzy connector I then jumped pins A and C (black and green) and it made no difference at all. I removed the jumper and left it just disconnected - same thing, no help. Don't know what this means.

I put the timing light back on and watched the timing mark. probably 50-75 percent of the time everything's OK and the timing mark is sitting right where it should. The rest of the time the light flashes, but there's no timing mark there. That's got to be wrong!

I put the timing light on the most of the other plugs and watched the hub for the fan (since the timing mark wouldn't be visible). Again, I could watch the fan bolt heads appear to move slowly around, then they would jump. Check my logic here, but I think that means I'm getting spark when I shouldn't.

Anyway - I'm open to any ideas!

[jgknowla1]

Originally Posted by irishman999

No sir, your esc does not advance the timing, it only retards it. To my best understanding of the system there is a knock sensor in the passenger side of your motor threaded into the block. That sends a signal to the Esc when it detects early detonation (pinging) and the ESC box will turn back your timing some how. Your distributor should still have the vacuum advance line plugged into the carb. Hope this helps.

Hey irishman999, thanks for the reply.

I don't have any kind of vacuum can on my dizzy and don't see anywhere for one to go. The last time I did the rotor I remember not seeing any mechanical advance weights either. I don't know what that means - could be a PO took stuff off.

[irishman999]

Are you running a HEI distributor with the coil built into the cap? I could be wrong but the original HEI is vacuum and mechanical weight operated.

Phasing out that ESC is the way to go, It could render your truck completely useless one day if it decides to act up. If your engine pings you just adjust your distributor back a little bit.

Chasing a firing issue is a pain in the ass for me. I start with checking everything one part at a time, I got stumped a while ago when my truck would start and run fine and then randomly have no spark at all when I tried to start it later. Turns out I dropped that little ground clip that went on the coil while doing my tune up.

[jgknowla1]

Originally Posted by irishman999

Are you running a HEI distributor with the coil built into the cap? I could be wrong but the original HEI is vacuum and mechanical weight operated.

Phasing out that ESC is the way to go, It could render your truck completely useless one day if it decides to act up. If your engine pings you just adjust your distributor back a little bit.

Chasing a firing issue is a pain in the ass for me. I start with checking everything one part at a time, I got stumped a while ago when my truck would start and run fine and then randomly have no spark at all when I tried to start it later. Turns out I dropped that little ground clip that went on the coil while doing my tune up.

Hey irishman999, yeah from what I can tell it's stock HEI and it does have the coil in the cap.

I'll definitely look into disabling the ESC - even if it's not THIS problem, I don't want it acting up in the future. I did a bit more research and found another forum (lost the link to it, though) where someone explained that the ignition module in these distributors put out spark with max advance and then the ESC retards it to where it needs to be. So I guess that's how it does electronic spark advance. Makes sense, but I don't know of any way to test it.

Seems like I need to probably switch over to a more standard HEI setup when I can find some cash to do it.

Thanks again!

[BigBlocksRule]

Are you sure you have a good balancer and that it's marks aren't moving (loose hub)?

[jgknowla1]

Originally Posted by BigBlocksRule

Are you sure you have a good balancer and that it's marks aren't moving (loose hub)?

Hey BigBlocksRule,
I did go underneath with the truck off and tried turning the balancer by hand. Couldn't budge it at all.

[BigBlocksRule]

You might try to get it to TDC to make sure it lines up.
Are you sure you have a good timing light? You might try testing it on another vehicle and see if the problem follows it...

[jgknowla1]

Originally Posted by BigBlocksRule

You might try to get it to TDC to make sure it lines up.
Are you sure you have a good timing light? You might try testing it on another vehicle and see if the problem follows it...

Good idea - guess it could be a bad timing light. I'll try to check it on another engine.

[jgknowla1]

Just to update those following this thread... I pulled the spark plugs to see if they had a story to tell. They all looked fine, but when I got to the last plug the wire popped right off leaving the metal clip on the plug.

Pretty sure that must have been a weak connection. Then I found another plug wire that was damaged. I replaced them and it seems like the surging/rough idle has cleared up a bit. It's still there for sure, but seems less now.

[78 Chevyrado]

Wonder if the timing chains stretched out... if its really stretched, it will make the spark do like you said, as the dist runs off the cam and a loose chain makes the cam run sloppy.

When the engine is pulling normal, the slack is taken up, but if it stumbles the slack suddenly reverses, and then the engine picks up again and the slack reverses yet again. it may be sparking when it should distributor wise, just the cam is making it spark at the wrong times.

simple check is to pull the cap where you can see the rotor and turn the crank with a breaker bar the normal direction to take up the slack, then turn it backwards while an assistant watches. see how far you have to turn the crank backwards to make the rotor turn. that will tell you quickly if there's a problem with the timing chain/gears, or the dist shaft having too much play or it may be a combo of the two.

Also something that will make it do funny things I JUST has a problem with; check your advance weight to make sure they're not siezed. while your there check the dist. shaft for side to side and excessive up and down play.

[jgknowla1]

Originally Posted by 78 Chevyrado

Wonder if the timing chains stretched out... if its really stretched, it will make the spark do like you said, as the dist runs off the cam and a loose chain makes the cam run sloppy.

When the engine is pulling normal, the slack is taken up, but if it stumbles the slack suddenly reverses, and then the engine picks up again and the slack reverses yet again. it may be sparking when it should distributor wise, just the cam is making it spark at the wrong times.

Also something that will make it do funny things I JUST has a problem with; check your advance weight to make sure they're not siezed. while your there check the dist. shaft for side to side and excessive up and down play.

Hey Kenny, thanks for the ideas. I had the distributor cap off yesterday looking for problems and tested the dist. shaft play while I was back there - everything seemed fine.

It does seem like it could be the timing chain slop you mentioned. How hard is it to replace that sucker? I don't have much experience with all this stuff yet, but I'm trying.

This truck is my daily driver, but income is scarce these days - so everything's got to be on the cheap side.

[MTCK]

Stick with it. I would try another timing light just to make sure that isn't the culprit. It does sound like a problem with your distributor, not likely the advance control. I wouldn't ditch it just yet. How long has it been since you did a cap / rotor? how does it look under the cap? Moisture? Corrosion? I'd start with the easy / cheap things first. If you end up ditching your distributor in favor of a mechanical / vacuum advance unit, they new parts will move over. Good luck.

[jgknowla1]

Originally Posted by MTCK

Stick with it. I would try another timing light just to make sure that isn't the culprit. It does sound like a problem with your distributor, not likely the advance control. I wouldn't ditch it just yet. How long has it been since you did a cap / rotor? how does it look under the cap? Moisture? Corrosion? I'd start with the easy / cheap things first. If you end up ditching your distributor in favor of a mechanical / vacuum advance unit, they new parts will move over. Good luck.

Hey MTCK,
I did take off the dizzy cap yesterday and checked everything out. It all looks clean without any moisture or carbon. I cleaned the rotor and put it back on, and cleaned the connectors as best I could.

Don't worry - I'm not even thinking about getting rid of the truck. I am thinking about getting rid of the distributor, but that'll have to wait a little while.

[78 Chevyrado]

Yeah the advance weights probably aren't related to your problem, its just something to check while your there.

When my advance weights stuck, i got a steady spark with my timing gun, they had just stuck fully advanced so the truck was way too advanced making it run crappy under 1500RPM.

It's about $45-$50 to change the timing chain everything included.

To replace a timing chain, you have to pull the water pump, harmonic balancer then the timing cover.. Some people have luck pulling the timing cover without breaking the oil pan loose, but I'm not one of them so when I do it, I go buy an oil pan gasket set, timing cover gasket set, and front crank seal.

Only special tool needed is a balancer puller. and put anti-sieze on the crankshaft snout before you reinstall the balancer. everything else just uses common hand tools.


If you should end up needing a new distributor, I recommend this one on ebay from skip white.
http://cgi.ebay.com/ebaymotors/SBC-B...item51958625a5

Here's a review of that ebay distributor
http://www.thirdgen.org/techboard/af...-65-000-a.html

I haven't used mine yet as it's for my new engine, but the quality looks just as good as any other high quality dist. I've seen in person and the best part is I got it for $38 or $40 out the door when it was on sale. Mine came in the same box and is the same brand, just mine has a clear cap instead of a red one like in the review.
Here's a link to pics of my new dist.
http://s160.photobucket.com/albums/t...20Distributor/

[jgknowla1]

Originally Posted by 78 Chevyrado

If you should end up needing a new distributor, I recommend this one on ebay from skip white.
http://cgi.ebay.com/ebaymotors/SBC-B...item51958625a5

Hey, thanks!
I'll take a look at that guy's ebay store.

[1LowToy]

I think youon the right track looking into the distributor, rotor and cap. Look at the cap and rotor again closely for crackes. I sure soulds like it's cross firing. While it's apart check the coil for proper resistance. A coil breaking down can feek out and do a lot of wierd stuff.

[jgknowla1]

Originally Posted by 1LowToy

I think youon the right track looking into the distributor, rotor and cap. Look at the cap and rotor again closely for crackes. I sure soulds like it's cross firing. While it's apart check the coil for proper resistance. A coil breaking down can feek out and do a lot of wierd stuff.

Hey 1LowToy, I'll try to take another look and see if there's anything hiding. The coil looks new, but that doesn't really mean anything. Thanks!

[jgknowla1]

Just for anyone keeping up with this thread... I tore my quadrajet apart yesterday and rebuilt it with the cheap kit from Autozone. For the most part, the problems I found were:

Float was deteriorating and flaking off on top (dry rot?)

The little spring that holds the float needle onto the float arm was nowhere to
be found. Not sure how it was running if this hanger spring was gone...?

The idle mixture screws seemed all out of whack - driver side was turned out 6.75 turns, the passenger side was out 4 turns. I put them back in at each 2 turns out.

I followed along with some videos on YouTube (user alpheus1975) and it went really well. I got a new float, fixed the problems I found and didn't have any play in the throttle shaft so no rebushing needed. I did order the bushings from McMaster-Carr for $0.51 each, but didn't need them. Was prepared to use the CNC milling machine at work to do the rebushing, but glad I didn't need to.

During the rebuild I chose not to put back on the idle stop solenoid or the choke. Neither has been hooked up since I've owned the truck.

I also disabled the secondary lockout since there's no choke now.

Time for results. MUCH BETTER! It accelerates much better - I can even feel it accelerate when I'm already going 55 now. Before it just didn't have any kick to it. I'm very happy with the improvement.

I also went ahead and ordered one of the Skip White HEI distributors. I figured it's worth it for $50 bucks to get the ESC out of there and then know what I have for real. Haven't gotten it in yet, though.

Thanks so much for everyone's help. I really appreciate it.