BB spark plugs ??
Thread Starter
Racer
Joined: Jul 2000
Posts: 395
Likes: 1
From: Los Altos Hills Ca.
BB spark plugs ??
Maybe someone can help on this one.
I need new plugs for my 427/425 L72 motor. There are some readily available AC R43XLS plugs. But the motor originally had AC 43N (I think).
Does anyone know if this is a good replacement?? Is the 43XLS a hotter or colder plug? (I'd prefer a colder plug). Does it stick out further into the cylinder..eg will it have interference problems? Does the R (resistor) affect performance?
Incidentally, I have the Petronix unit with the Blaster coil for my ignition (works great!). Currently have Autolite plugs (don't ask). Running at around 10:1 compression due to flatter pistons but do have the correct cam in there.
Thanks,
Mark
I need new plugs for my 427/425 L72 motor. There are some readily available AC R43XLS plugs. But the motor originally had AC 43N (I think).
Does anyone know if this is a good replacement?? Is the 43XLS a hotter or colder plug? (I'd prefer a colder plug). Does it stick out further into the cylinder..eg will it have interference problems? Does the R (resistor) affect performance?
Incidentally, I have the Petronix unit with the Blaster coil for my ignition (works great!). Currently have Autolite plugs (don't ask). Running at around 10:1 compression due to flatter pistons but do have the correct cam in there.
Thanks,
Mark
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: BB spark plugs ?? (hot1corvette1)
the XLS are extended tip plugs so you can run a hotter R45XLS because the fuel wash will keep the plug tip cooler because the extended tip is farther into the chamber.this will prevent the common problem of the plugs carboning up that happens in BBC. a R43XLS will act like a colder plug because of what i stated before. to prevent any carbon filing from being baked on to the plug always run up the RPM at part throttle to max RPM the first time after driving around town.unless you are racing there is no need for colder plug than a R45XLS. :chevy
Le Mans Master
Joined: Apr 2000
Posts: 5,104
Likes: 1,362
From: New York New York
2024 C1 of the Year Finalist - Unmodified
2024 C2 of the Year Finalist - Unmodified
2023 C2 of the Year Finalist - Unmodified
2023 C1 of the Year Finalist - Unmodified
Re: BB spark plugs ?? (hot1corvette1)
The 'N' series plug has been dicontinued for quite a while. The difference is the shell is threaded all the way up to the gasket area, whereas the 'N' was not.
The 'R' is resistor, and it will not effect performance.
The 'S' is projected tip. Since you put flat pistons in, I don't think you should have a problem.
As far as Autolite plugs, I prefer them to AC, they don't foul as fast, and they haven't removed heat ranges.
The 'R' is resistor, and it will not effect performance.
The 'S' is projected tip. Since you put flat pistons in, I don't think you should have a problem.
As far as Autolite plugs, I prefer them to AC, they don't foul as fast, and they haven't removed heat ranges.
Drifting
Joined: Nov 2001
Posts: 1,658
Likes: 25
From: Rochester Minnesota
Re: BB spark plugs ?? (hot1corvette1)
I switched to Champion plugs in my 427/435 in an effort to get alway from fouling. The crossover from the standard Delco was to an N10Y. That fouled too. I then went up in heat range to a N12Y. That worked fine for "normal" duty which meant an occasional blast through the gears to 140 mph (I was only 25 when I took delivery of the car and I wasn't really as smart then as I thought I was). :jester I've used them (or a derivative like RN12Y) ever since.
[Modified by 427435, 2:29 AM 12/3/2002]
[Modified by 427435, 2:29 AM 12/3/2002]
Thread Starter
Racer
Joined: Jul 2000
Posts: 395
Likes: 1
From: Los Altos Hills Ca.
Re: BB spark plugs ?? (427435)
OK...thanks for all of the info. It seems that there are several different options. I'll check local availability and see what I can get.
Thanks, again.
Mark
Thanks, again.
Mark
Melting Slicks
Joined: Dec 1999
Posts: 2,489
Likes: 32
From: New Smyrna Beach FL
Re: BB spark plugs ?? (hot1corvette1)
I had all sorts of starting problems with the AC plugs (R43XLS). I changed to the NGK that cross references to the R43XLS and the car starts first time everytime. So, I may never switch back to ACs again.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Re: BB spark plugs ?? (hot1corvette1)
Early 396`s and 427`s use the 3/4 reach plugs. The same as the 392 and 426 Hemi`s. The extended tip {S} will not interfere with the piston even though it looks like it may be too deep into the cylinder. R 43 XLS to R 45 XLS or any equivalent in another brand will work fine. For pure racing Champion N 58`s with the retracted tip would be a better choice. Especially with a blower. :flag :thumbs: Good luck :)
