Changed spark plugs

[K4fxd]

I first ordered 6510's from O'reily (none in stock, had to wait a day) when I got them home I checked them out and 3 were counterfeit. Would be 2 days before they could get more. They had 6509's in stock, they were not counterfeit. So being the impatient SOB that I am, went with the stock heat range.

The Ford plugs that came out are rebranded NGK's LTR6DP13's, all were around .060 gap. Even with COP this is a ridiculous amount of gap for a high compression engine that spins 7000 plus RPM. Cylinder #4 looks lean, passenger side rear. No signs of aluminum. There were sharp points on the ground electrodes that I'm sure were causing pre-ignition. So the computer was pulling timing.

The new NGK's also had sharp points on the ground electrodes. A bit of polishing took care of that. Shouldn't need to do this on an almost 10 dollar plug. I also gapped at .035

Anyone have a part number for a V-power plug ?

Test drive was very good. Engine sounds a bit more crisp and throttle response is better. I data logged and it is adding 2 to 3 degrees more timing across the board, so the polishing and or reduced gap did what I hoped for.
I really should have been patient and waited for the colder plug, it might have added another degree or so.

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[Rapid Red]

What tipped you off you got counterfeits ?

.060 gap is not that unusual, not looked into the Ford plugs. But I can speak to MSD & Crain ignitions, run .060 plug gap . 035 is old school these days, my lawn morrow is .035. Might want to stay with the factory spec.

Heck these new cars will 90k on a set of plugs easy..... if you wanted to.

"pre-ignition" I had that happen to one of mine. Would only happen running 70, pulling up an incline (intermittently).

It turns out it was a block knock sensor, lives in the valley. It was not seated/sealed from the factory, water got in and rusted that bad boy.

 

[ice445]

.035 is pretty aggressive for NA, I know a lot of stock boosted engines that aren't much lower than that. If you settled at say .045 I could understand more

 

[K4fxd]

The first tip off that they were not real was a cardboard thread sleeve, the others had clear plastic. The second clue was they did not have the part number etched in the barrel. Just said Japan. the third was the 4 digit code on the flat started with a c

.035 is a gap that has worked for me for almost 40 years. It is enough to light any mixture and does not over work the coil.

Pre-ignition is caused by hot spots in the combustion chamber, sharp edges on the plugs can cause this. It gets read by the knock sensor as knock, and will cause the computer to reduce timing.

 

[Rapid Red]

I.am with you on the .035 gap, same here many years. Having MSD & Crane ignitions installed on 2 other HotRods. Gap rang is .045 - .060 was why I mentioned it.

The knock sensor causing the ping was found using a code reader. Had it not thrown a code. I would have been looking at the same area as you, plug heat range and timing.

Good catch on the counterfeits, ain't it great. Just imagine what's out there on Ebay and the likes...?

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