JeepTherapy
New member
With the marginal snow conditions I am struggling to find a place to run my sled hard enough to jet it. OK, it scares me...
Anyway, my question; Should I change main jets and clutching at the same time or should I change one, test it and then go back and change the other?
Testing config/results; ~10*, ~75% humidity, 170 main jets, 55 pilot jets. Heel Clickers with grey spring and their recommended weight distribution. (was good before pipes, but limited run time) Bender pipes, peak head with 22ccs. WOT is rich, plugs look wet, clutch engage at ~4600, WOT ~8200. 1/4 throttle 1/2 mile run the plugs come out great, throttle response seems good.
My thoughts; replace the grey spring with the red spring, start over with weights as per MrViper700 setup. Replace the 170 mains with the 167.5s.
Retest...
I do think I will end up raising my needles (lower clips) and changing pilots to the 52.5s because it seems very rich at idle. Fouls plugs very easy at idle. Is that right thinking? Screws are at 1 7/8s, Should I just turn the screws in a small amount? 1 1/2?
Does that sound right?
Anyway, my question; Should I change main jets and clutching at the same time or should I change one, test it and then go back and change the other?
Testing config/results; ~10*, ~75% humidity, 170 main jets, 55 pilot jets. Heel Clickers with grey spring and their recommended weight distribution. (was good before pipes, but limited run time) Bender pipes, peak head with 22ccs. WOT is rich, plugs look wet, clutch engage at ~4600, WOT ~8200. 1/4 throttle 1/2 mile run the plugs come out great, throttle response seems good.
My thoughts; replace the grey spring with the red spring, start over with weights as per MrViper700 setup. Replace the 170 mains with the 167.5s.
Retest...
I do think I will end up raising my needles (lower clips) and changing pilots to the 52.5s because it seems very rich at idle. Fouls plugs very easy at idle. Is that right thinking? Screws are at 1 7/8s, Should I just turn the screws in a small amount? 1 1/2?
Does that sound right?
turn the screws in first, if you get to about .50-.75 turns out total then I would jump down in pilotjet size, the fuel screws usual area or operation is 1 turn to 2 turns out.
run the sled at idle, and very low speeds, then whack the throttle from a dead stop, does it bog or rev up nicely? after idling are the plugs fairly dry/ if yes then your ok on the pilot jets and fuel screw settings
then run the sled at half throttle for a small stretch keeping it at half throttle, a good 350ft at least, shut it off and pull the spark plugs, should be nice and dry, light brown and good wash on pistons. adjust clip up or down to compensate.
finally take the sled out again and run at least 500-750ft at wide open throttle, do the same plug and piston wash checks and adjust your main jet size to suit color/wash.
run the sled at idle, and very low speeds, then whack the throttle from a dead stop, does it bog or rev up nicely? after idling are the plugs fairly dry/ if yes then your ok on the pilot jets and fuel screw settings
then run the sled at half throttle for a small stretch keeping it at half throttle, a good 350ft at least, shut it off and pull the spark plugs, should be nice and dry, light brown and good wash on pistons. adjust clip up or down to compensate.
finally take the sled out again and run at least 500-750ft at wide open throttle, do the same plug and piston wash checks and adjust your main jet size to suit color/wash.
JeepTherapy
New member
thanks Don, sounds about like what I was doing.
Plugs are wet when idling, will turn the screws down a small amount then and test that. 1/4 turn enough?
Plugs are wet at WOT, will drop one jet size and test again
Plugs were dry and nice color at mid. Will leave that as it, but test it again after the other changes.
Going to leave the clutch as is until I test the jetting.
Plugs are wet when idling, will turn the screws down a small amount then and test that. 1/4 turn enough?
Plugs are wet at WOT, will drop one jet size and test again
Plugs were dry and nice color at mid. Will leave that as it, but test it again after the other changes.
Going to leave the clutch as is until I test the jetting.
JeepTherapy
New member
I think I have my primary where it needs to be. Revs right to 8600 from most speeds. From higher speeds it seems to only go to 8400. I am going to add 10* twist. I assume that is what backshift is?
Here are some pics of my plugs. All three look the same for the most part. I think part of it is technique, how long I let the motor coast before stopping? I don't really see "wash" does it take a while to darken the clean pistons so it shows good?
Bender piped Viper, Peak head with 22cc domes, heel clicker primary, Red spring, 4.8-0-0, Bender 02VTP helix
165 mains, 55 pilots, 1 3/4 screws. 20 degrees out unknown humidity
from what I get out of the plugs these look pretty good. Wanted to make sure you could really see them so I cut them open. The 1/16 to 1/8" ring at the bottom means I am very close to correctly jetted as long as I stay in the same temps to slightly lower?
Here are some pics of my plugs. All three look the same for the most part. I think part of it is technique, how long I let the motor coast before stopping? I don't really see "wash" does it take a while to darken the clean pistons so it shows good?
Bender piped Viper, Peak head with 22cc domes, heel clicker primary, Red spring, 4.8-0-0, Bender 02VTP helix
165 mains, 55 pilots, 1 3/4 screws. 20 degrees out unknown humidity
from what I get out of the plugs these look pretty good. Wanted to make sure you could really see them so I cut them open. The 1/16 to 1/8" ring at the bottom means I am very close to correctly jetted as long as I stay in the same temps to slightly lower?
looks pretty good
JeepTherapy
New member
MrViper, I have been searching the old posts looking for your "reading plugs" tips. I couldn't find one. You mentioned that you were going to write one in a post a year or two ago. Have your written one and I just didn't find it?
I have learned that there is a lot more to reading plugs than just looking at the color. I am interested in the black ring around the bottom, the ground strap color/burn distance from the bend, and the coloring/ring around the center electrode.
Also interested in your method of doing the spark plug chop I think they called it? Just how should the kill switch and the rundown be done. I did a few where I didn't touch the brake and that seemed like it was wrong by making the plugs wet?
I respect your wisdom and would like to hear what you have to say about the subject.
I have learned that there is a lot more to reading plugs than just looking at the color. I am interested in the black ring around the bottom, the ground strap color/burn distance from the bend, and the coloring/ring around the center electrode.
Also interested in your method of doing the spark plug chop I think they called it? Just how should the kill switch and the rundown be done. I did a few where I didn't touch the brake and that seemed like it was wrong by making the plugs wet?
I respect your wisdom and would like to hear what you have to say about the subject.
Last edited:
mopar1rules
Active member
i don't see what ring you are talking about at 1/16"-1/8" from the bottom.
JeepTherapy
New member
Look at the porcelain that actually is exposed inside the cylinder. It is very white where it is covered by the metal of the threads. Then there is a black ring, then the brown color. The very bottom edge of where it is exposed in the cylinder is a black ring all the way around it. It is about 1/8" to 1/16" wide.
I know very little about tuning and spark plug reading. Hopefully MrViper will chime in.
I know very little about tuning and spark plug reading. Hopefully MrViper will chime in.