I have a small block Chevy 91 RS bored/stroked to 383. 9.7:1 Comp, Stock heads and medium aggressive cam. Holley 750. I spray 150 NOS Power Shot system. I noticed my idle getting rough so I pulled my plugs today to inspect and found # 5 and #6 ground straps burned halfway off. Also #8 has a heavy build up of white stuff on the strap and electrode. I'm thinking I have a lean condition and detonation.
Any thoughts,
Thanks
Dave

 

Is that kit a wet shot or dry. The way it sounds you ran it way to lean.

 

sounds like a lean condition and your spark plug gap is to large. try a set of one step colder plugs and dropping the gap down.

 

Join Date: Aug 2008
Posts: 2
SN17 has a reputation level 5-49

I was using AC Delco R45TS plugs. I am begining to think they may be two hot. I talked to NGK Tech and they recomended NGK 7773s as two heat ranges below the stock plugs and I changed them tonight. I also think my timing was to far advanced. My light says I was at 38. I went to 36 this afternoon and she ran much better and was much stronger. I use 93 pump gas. I also had a lean condition when I did spray. That may have also contributed. I leaned out because the single pump I have wasnt able to feed the carb and the nitrous system combined. I added a dedicated fuel pump and seperate fuel cell to the nitrous system last week.
Dave

 

oh geez ! you were running full timing on stock plugs?!? Yea, R42T would work great, and 32* timing at that shot size.

 

That R42T would be 2 heat range colder than stock for a 1991 engine. That is a stock plug for a 1986 V8 Camaro. I always buy the 1986 (cold) plugs for everything. You could also go with the Autolite Racing AR24 or AR23 plug that is cheaper than the AC Delco plugs.

What would NGK recommend for a 1986 Camaro with a stock cold plug vs. a 1991 Camaro with a stock medium plug?

38* of timing is too much even without the N2O active. You are probably better off at 34* or less N/A, and 30* or less with the N2O active.

 

R42T is stock for an '86 Camaro? Really?!? It's a damn cold plug... I thought the R45TS was stock for all V8 Camaros in the 3rd gen...
Yea, I only mention the R42T because it's a P/N that i've memorized. Delco plugs are black oxide coated on the threads, making them next to impossible to read. I prefer Champion (RV8Y or something?)

 

Yeah, the 1986 models had colder plugs. The parts store catalogs will show it. I came across this when doing the turbo stuff. I wanted a lower heat range plug and run Autolites. The factory plugs were 26 and I knew my older TPI had stock plugs which were 24. The last number is the heat range.

Isn't the NGK 7773 plugs a non-resistor plug (bad for ECM) and a heat range of 2 (really cold). The really cold part is OK, but the non-resistor part???

EDIT: The Champion RV8C is a heat range of 4 (same as Autolite AR24), correct? The Autolites are nickel plated and read fine.

EDIT: Just noticed the poster runs a carb........so the non-resistor plugs are OK......radio problems? Correct plug wires?

 

the v6 cars are all r42t and r43t plugs easy way to remeber if u cant rember the number when u goto the store, 42's are 86 and prior and 43's are 87 and later

speaking of plugs i need something colder then the 42 for my car anyone got a cross refrence on another brand that would be 1-2 ranges colder? in delco 42 is the coldest they go

 

What about an AC Delco R42CTS? It appears to be one heat range colder than the R42T.

 

what does the c denote??
i know the stock v6 plug is a r43/42tsk
k denotes special but ive never been able to find out exactly what special means lol

 

Depends on where it is. That C is either copper core or one range colder. If the C is in front, its a commercial plug and has a larger electrode.

 

hmm i might have to go pick up a set, **** its 6 bucks for a set of 6 so if they dont work im only out 6 bucks and i throw the 42's back in im due for a new set of plugs anyway, i change mine out after every 5-8 runs using the antilag system since they get fuel soaked.
lol i might have to buy stock in delco once i switch back over to the 74mm turbo ill be using the anitlag ALOT one race day if i go rounds would be like 2 sets of plugs lmao

 

C = one range colder in this case. So it is one range colder than the R42TS