Reading the spark plugs

Cdaniel · Sep 12, 2004

So I've been fooling around with ignition stuff in search of a smoother idle. I upgraded the wires to 8mm and added an Pertronix Flamethrower coil. I regapped the Autolite 45's to .040. After maybe 150 miles and much fiddling with timing and carb adjustments and not much success, I pulled the plugs to put the gap back to .035. Wow I say! What happened to the center electrodes? Every one of them has significant erosion/melting. The ends have been rounded, no longer flat.

So, what have I done? Too much spark for these plugs maybe? Is a colder one in order? Or a more exotic platinum type?

Reccomendations?

TOM B · Sep 12, 2004

SOUNDS LIKE THE TIMING IS WRONG, runing to hot, ping.

Cdaniel · Sep 12, 2004

TOM B said:
SOUNDS LIKE THE TIMING IS WRONG, runing to hot, ping.

Ok, but the funny thing is I've actually got the timing dialed in finally. I was battling some "ping" before but it's under control now and the plugs looked good at that point. I am having cooling issues though. I think it's a low capacity and insufficient air flow problem there

Route666 · Sep 13, 2004

Look at this page. I know it's for air-cooled motorbikes, but I don't see why the same principles wouldn't apply here.

http://www.motocross.com/motoprof/moto/mcycle/plug2/plug2.htm

About halfway down, just under the plug covered in oil you'll find what sounds like your problem: too hot, pinging (lean/low octane/wrong timing), burning up plugs.

You could have a too hot plug. You might need a cooler plug, or your cooling problems might be causing it. You also could still be running lean, not to the point of pinging, but still hot.

Cdaniel · Sep 13, 2004

Route666 said:
Look at this page. I know it's for air-cooled motorbikes, but I don't see why the same principles wouldn't apply here.

http://www.motocross.com/motoprof/moto/mcycle/plug2/plug2.htm

About halfway down, just under the plug covered in oil you'll find what sounds like your problem: too hot, pinging (lean/low octane/wrong timing), burning up plugs.

You could have a too hot plug. You might need a cooler plug, or your cooling problems might be causing it. You also could still be running lean, not to the point of pinging, but still hot.

Hmmmmmmm, yep I've seen these pics elsewhere before. I'm thinking I better get this cooling under control before I start chasing my tail on plug heat range and carb jets. But too lean would be my last suspect, I think this carb is doing what it should (it had better for the money spent at Pony carbs). The thing that puzzles me is the plugs were fine until I changed the wires and coil and/or I reduced the total advance. A reduction in advance is supposed to reduce heat in the engine right? So the hot spark looks like the culprit to me. Or am I missing something?

Route666 · Sep 13, 2004

Well that page says that poor engine cooling can be a CAUSE of the eroded plugs, not a symptom. Maybe your radiator has gotten a little clogged or your thermostat isn't working proper, or the pump isn't pumping enough.

Cdaniel · Sep 13, 2004

Route666 said:
Well that page says that poor engine cooling can be a CAUSE of the eroded plugs, not a symptom. Maybe your radiator has gotten a little clogged or your thermostat isn't working proper, or the pump isn't pumping enough.

I think the radiator just isn't up to the task. It's a "high efficiency" 2 row (jumbo tubes) but it just can't handle job. Even at highway speeds it's pushing 210f. In traffic it climbs from there. I actually pulled it and had the shop check for clogs. It had a few but not much. I put a Gano filter on it just to be sure. The 134 A/C condensor doesn't help matters either. The pump is new and the stat opens right on cue at 180. 6 blade fan with a "hipo" shroud. I'm getting a 7 blade clutch fan but I expect to end up with a different radiator, probably aluminum.

Route666 · Sep 15, 2004

If your radiator isn't keeping it as cool as you'd like, I'd replace it, if I had the cash, and it might solve your sparkplug problem too.

Someone else should chime in and lend a hand though, those with more actual experience with mechanicking. I'm no certified expert, maybe ask a mechanic (preferably an older-car mechanic).

Good luck.

Cdaniel · Sep 15, 2004

Route666 said:
If your radiator isn't keeping it as cool as you'd like, I'd replace it, if I had the cash, and it might solve your sparkplug problem too.

Someone else should chime in and lend a hand though, those with more actual experience with mechanicking. I'm no certified expert, maybe ask a mechanic (preferably an older-car mechanic).

Good luck.

I probably will change it. Arizona's no place to have marginal cooling. And I'm not expecting much difference with the clutch fan. Except a little bump in mileage hopefully. I changed the plugs out for some platinum Autolite 45's. The parts guy says that 45 is the coldest available in that line. I'm hoping the platinum ones will tolerate the heat a little better. The idle improved some. But I still have something causing an imbalance at idle.

gjz30075 · Sep 15, 2004

I have a three row stock rad with a 6 blade fan on my '66 with air and it cools just fine. Fan noise is too loud but I think the three row is more efficient than a 'high efficiency' two row. A three row has more surface area, which is needed for better cooling. Plenty of stock three row radiators on the market for reasonable prices.

Reading the spark plugs

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