Neueb question.

Factory is 028 - 032.

I put in new plugs and only now considered the plug gap.

The 'old' WR5DC+ plugs were put in as they came out of the box @ 032. After ~5K miles they measure 034+. I put the new plugs at 028 (gapping pliers), but I'm wondering if that's too conservative?

Is gap a factor >300 rwhp/tq?

 

I believe the gap is determined by the strength of the electrical ign system and the compression of the cylinder.

If the engine and ignition are stock set the plugs at 30 and monitor from there.

 

I am running .045 on mine, but I am not using the factory coils and mine have a longer time to build a charge at higher RPMs.

 

Im running the stroker engine with the 5s at stoc .028". they look real black, and i wonder if thats a function of being too rich or could the colder plug be a factor?
I also drove home from the races and have been running the car in idle for the last few days adjusting the clutch. It starts out real rich until the closed loop cycle starts.

Mk

 

If you're running rich, you may need a hotter plug until you SharkTune.

 

Mark............the answer is yes that spark plugs that are of too cold a heat range shall build up carbon and eventually foul.

Conversely a plug that's too hot will give indications of running 'lean' and shall cause pre-ignition. If you read Carls book on his Pikes Peak run he discusses the many test runs he did consumming many sets of plugs to get the heat range correct............remember once they're 'coloured' you have to install a new set and start anew.

 

It looks like that is happening with these plugs, but its hard to tell, as i have a lot of rich start ups. after race day, the plugs were very clean.

Here is what they look like after a 10 min hyway run and some 60-100mph bursts.

mk

 

Ken I run stock, in other words the smallest (.28 in this case) ....

 

I would assume that factory max gap takes into account the wear factor. I used to tune up a lot of cars from the 80s, and I would change out plugs with extreme high miles, and huge gaps. From what I coiuld see, carbon deposits and wear on the cap and rotor were the spark limiting factor on high energy ignitions. I would expect that a larger gap could contribute to cap wear slightly, but not signifigantly.

YMMV

 

Is anyone else seeing this? (trick question since I've received a few e-mails asking me to "enhance" the image).

Not my best work, but the original is kinda dark & small. Are those pieces missing from the porcelain of the spark plug?

 

Ru Roh!

 

You guys!! No, the porcelain is not missing. its jus smudging of the carbon film on the insulator. its hard to see anything with a magnifying glass now, as its just all dark. Im thinking around town is tough on the plug, but at the track with the higher percentage of WOT, its easier for the plug to be cleaner. The engine is running smooth as silk.

mk

 

It might be an idea to return to stock plugs; do the high speed run/WFO plug chop analyse the plug colour and make decisions from there.

A quick call to Carl may save much time and spark plug expense as he's BTDT.

 

I always like to look for a nice brownish tinge on my plugs, like a finely roasted marshmallow. Mmmmm, now I am hungry.
I agree with the previous poster, try some hotter plugs in that thing, Speed Racer.

 

Here is the close up. Same plug, angle and you can see there is nothing wrong with the insulator. 1st two picts are the same plug as above that hacker tried to "enhance"

Also, a prior picture of one of the plugs at the track.

I do want to try the stock plugs again, maybe through a practice session and see what they look like. But, the cold plugs looked pretty normal after a racing session. around town, and the idling i did in fixing the clutch, goo'ed them up a bit.

mk