ctgreddy

I just bought a nitrous kit, and am going to get new plugs, right now i'm running autolite 3924 plugs, what would one heat range colder be, 23's or 25's?

also i don't plan on using this kit much, just when i get beat or on track days, that being said do you think my block would handle a 125 shot if i shift at 6k? I was planning for just a 100 shot but might get greedy in the quest for 10's.

mjr46

3923's = 1 step colder, and FWIW I used standard range of 3924's with a 100 shot on mine fine

ctgreddy

what'd you set your timing at when you were spraying?

mjr46

TOTAL WAS AROUND 28-30 TO BE SAFE, pull your spout and lock it out there for efi ...I have a msd adjustable set up on my carbed ride so i can control it with bushings p.s , I also ran race gas that day for added protection

ctgreddy

ok here's where i'm confused, how do i check total timing? i've only ever checked based timing, and for spray i was thinking around 8*.

mjr46

8 DEGREES IS YOUR BASE + WHAT EVER THER ECM BUMPS TIMING UP TO in accordance with rpm vs spark schaler tables, I've seen upwards of close to 40*..........you can try to rev it to around 3500-4000 and hold it and check it with a light, that's what I have done but since ecm controls timing at that point with spout in, rpm and the fact there will be no load on it may not deliver the full spark advance/hence hide a few in the bag, which is why I suggest pull the spout at the track and rotate distributor while holding a light on balancer and when you hit 28 ish to 30 stop. then to verify it bring revs up to around 3500-4000 and make sure the mech advance portion in the distributor doesn't advance it past 30, if it does rotate dizzy back a tad

ctgreddy

so you're saying to pull the spout, set base at 28/30*, and keep the spout out so that all the electronic advancement is taken out correct?

nitrous_bob

i use stock coppers for 80-100 shot as well.

i gap at about .042" and use 10* timing , all with 87 octane if it isnt really hot out

i have on good days gone as high as 14* timing and 89 octane while squirting 80.

IMO the BEST thing to do is powertime it a few times at the track, start at about 8* and run it...note temps and humidity. then bump 2* per run until your MPH starts to tail off..... you'll slow down a bit b4 the effects detonation hurt anything, and well b4 you can hear anything

do that on a few different types of days and note the temps and humidity.

range fromm cool and dense to hot and humid..... it wont take long at all and you'll know exactly where you need to be based on the ambient conditions

i typically ONLY change octane OR timing if i was already full with something wrong. never really both, no real need to do that on a small shot

ctgreddy

i always run atleast 93 in my car, sometimes 94. so if i knock the plug down to a 23 at .042 and set base timing at 10* i should be safe in that area correct?

another question, i got a window switch that connects to my wideband and shuts it down if a lean/rich condition occurs, but with nitrous am i still looking for an afr of around 12.5/13.0:1? or do you want richer/leaner? just trying to know what to look for.