Jer82Z28

hey guys, was out at the track the other weekend for the first time this season and i ran into some issues tuning the carb. The day was super weather wise, the air density was 2000ft lower than usual so I was hoping for some record breaking runs, however I was slower than ever. since the air was so much better I concluded that i must be running lean, except when i checked my plugs, they all showed a dark tan to light brown.. slightly rich? I scratched my head. I decided to trust my spark plugs and I leaned the secondaries further, I gained nothing with my tuning, I didn't get a chance to rejet back to my baseline but it just feels like its running lean. its way down on power and doesn't bog. Is it usual that older plugs will start showing different readings as they get used? how often do I have to change plugs to maintain their accurate readings? I only have maybe 4000 miles on them.

five7kid

iTrader: (14)

While 2000' is a bit much, I have gone slower with improved DA because relative humidity went up as well. Performance doesn't always follow DA. And, conventional wisdom says don't base tuning on ET - MPH is the better gage, and you still need to take wind into account with MPH.

It doesn't sound like plug age is an issue. I've had two-year-old plugs change color with a single run. But, make sure no other tuning parameters are to blame, such as timing.

Last weekend I lost a tenth because one of my cool air ducts fell off. Make sure you don't have anything simple happening (like throttle blades not opening completely due to something like the air cleaner interferring with them).

Jer82Z28

thanks five7, yea i go by mph when tuning and was down 4mph from last years best at 4700 ft. was at 2600ft last weekend! feels like a missed opportunity.

it baffled me though that the plugs would show stoich-to slightly rich while the car acted like it was running lean.
I never really gave it it's seasonal tune up either since i was rushed to get to the track, I will be sure to do that for next round.