Sparkplug problem or more??

Philip Messer · #1 (**permalink**) 12-27-2006, 09:27 AM

I need some expert feedback!

While driving my Backdraft over the weekend, I suddenly incurred a loss of power. The idle was OK, but the Windsor Ford Racing crate 392 stroker was hitting on only 7 cylinders upon acceleration. I pulled the 4 spark plugs on the passenger side of the engine and discovered the ground electrode on the back plug was pushed up against the center electrode, leaving essentially no gap!! The plug was black and not cocoa colored revealing it had not been firing. I cleaned the plug and reinstalled all 4 plugs and 200+ miles later, the engine runs as good as ever, perhpas even better!!

The engine has 2000 miles on it and I have not pulled any plugs prior to the weekend loss of power. I am pleased for now that the engine runs as strong as ever, but I have concerns as to how and when the plug gap closed and can it happen again! Could the plug have been installed this way and it took 2000 miles of driving to foul out? Could I have pumped up a hydraulic lifter and pushed the gap closed with a valve? Could there be a piece of metal floating around in the combustion area (I can't hear any strange noises and the cylinder compression checks OK)? Do I have a piston or a cam problem (I doubt it as I would expect a recurrence of the problem within the 200+ miles driven since!).

Any other ideas? Any elaboration on my thoughts? Anyone had similar experience?

Phil from Phoenix

Excaliber · #2 (**permalink**) 12-27-2006, 09:41 AM

No gap or a VERY small gap? If it was a teeny tiny gap the plug and cylinder could still fire and it might take a couple of thousand miles to show up as 'fouled'. It's not uncommon for plugs to be dropped at some point during manufactur or shipping or installation and the side electrode gets 'bent'. LOTS of times plugs are installed without really LOOKING at the gap as they come out of the box. You might check one or two and determine there 'good to go' right out of the box, but you missed the ONE damaged plug! I've seen this happen a number of times over the years and now I visually inspect every plug.

Tim Brewer · #3 (**permalink**) 12-27-2006, 09:50 AM

It may or probably have been put in that way. You can't pump up a lifter and make the valve close the gap, valves and sparkplugs live side by side and it is impossible for them to touch. It is also impossible for a cam to cause any problem either. One thing that could cause a problem like this would be too tight of a piston/ head clearance. But if that were the case, you would have a problem with all your plugs. Also make sure you have the correct reach/length plug. But I think you have everything under control for now.
Good luck...
Tim

Philip Messer · #4 (**permalink**) 12-27-2006, 10:39 AM

Excaliber,
Tim,

Thanks for the timely response! Yes, there was a VERY small gap that looked carboned over. So, I also feel the plug was installed in that condition and it took 2000 miles to crud it up. I also felt there was no way a valve could have bent the ground electrode (and still have the engine run at full power following the plug gap fix.) The engine runs sound and strong!

I have owned the Cobra since near new. I doubt that the plugs have ever been removed since original installation by Ford Racing. Any thoughts or feedback on their quality control?

Excaliber · #5 (**permalink**) 12-27-2006, 10:59 AM

Stuff happens? Assembly line worker got 'lazy' and simply failed to check that plug before installing. After all the last dozen boxes of plugs he installed were 'perfect', this one got by him.

Philip Messer · #6 (**permalink**) 12-27-2006, 11:39 AM

Excaliber,

We have a place in Kihei, Maui and usually spend a day or two in Oahu on the way over and back. I will let you know when I will be in your area. I would like to see your 427.