Spark plug gap ????

V

VictoryTrans

The cars stock....I swear
Joined
May 24, 2001
The plugs were gapped at .035 and the car was popping alot at 6000rpm, a new coil pack and module are going in, but just to cover all the bases I asked around about what else could be wrong. Someone said to gap the plugs at .025, are there any side effects to this?? ie. rough idling, etc? Thanks
 
Originally posted by buickboy
Tight .035 on AC's CR43TS always works for me. Gone low 11's no problems.
Mitch
Click to expand...

Well, the problem is........035 is supposed to be the factory recommendation for a stock car. This is a car that should run mid 8's w/ 30psi........I dont know if .035 will cut it. As for takin it one step at a time, my dad doesn't really want the car to pop anymore, cuz the popping just blew another head gasket, so he really cant take the chance just in case .030 isnt a close enough gap. This guy told me he went from .035 to .025 and picked up 70rwhp. Somethings definitely wrong when it wont rev past 6000 on the dyno, but it should be pullin past 7500.

BTW, thanks for the input guys:)
 
i bet the reason why it's popping is because the spark is getting blown out with such high psi of boost...a much tighter gap will help that problem since it will be near impossible to blow out a .025 spark gap...since the car isn't streetable i wouldn't worry about driveability...the tighter the gap the worse the car will drive on the street basically...yes .032-.035 gaps are for a near stock car...i run ac delco cr42ts plugs with a .032 gap....i run 27 psi of boost on race gas and 24-25 lbs on 93 pump gas and dual nozzle alky...
 
Plugz?/

Tony, Reggie West had the same problem. I think he posted once he went from .032 to .025, no other changes, the car picked up a 100 HP on the dyno pulls.. back to back..

I have the DIS4-HO and run my plugs at .028.

HTH:cool: :cool:
 
Thanks.......I just kinda wanted someone to second the notion of a .025 gap, so I knew it would probably help. But even thought it might not seem like it, drivablity is somewhat of an issue, because my dad does want to do some limited street driving, but I'm sure he'll make an exception, I think its worth not blowing out anymore head gaskets:D
 
Originally posted by VictoryTrans
Chuck, what would you recommend we start at with a Standard DIS-4 box??
Click to expand...

BTW, Reggie is the one that told me to try the .025 gap:)
 
GAP??

I like tite gaps!!:eek: :eek: I'd try the .025 and see if it helps..
Some guys even file the ground electrode back to expose more of the flame kernel to the air/fuel mix. I've not tried that yet...

Back under my rock;) ;)
 
Did you allready have the MSD in when it was poping? I spoke to MSD a while back and they mentioned that you need a bigger gap on the plugs because the spark is getting amplified by the MSD.

I ran 27psi with it gapped at .035 with no problems. Car use to miss here and there with CR42's but the problem was fixed with the UR4's.

But then you car runs in the 8's :eek:
 
Some guys even file the ground electrode back
Click to expand...

That can cause some real bad things in the ignition system. I know Chuck doesn't do this but I wouldn't recommend it; leave that to the guys in nothing-matters-but-a-win racing. .032" stopped my popping. Works fine on street gas too.
 
Re: GAP??

Originally posted by Chuck Leeper
Some guys even file the ground electrode back to expose more of the flame kernel to the air/fuel mix. I've not tried that yet...Back under my rock;) ;)
Click to expand...

I have only found this useful on street plugs like the Autolite 23 or 24. If you look at the electrode on the street plugs the little metal or ground, sticks out past the electrode so your spark can jump or ground in a large area. Cutting it back gives a shorter distance for the spark to jump and a smaller area.

Plugs like the Autolite 133 are a race plug and don't need this because the ground piece is already cut shorter from the factory
so trimming them is not needed. I don't know of any one who files the electrode it self, just the ground piece that it arcs to.

The plugs above are used on the stock iron heads. The 103's for the Champion heads also don't need any work because there cut back from the factory.

Take Care
 
You're gonna think I'm nuts, like my wife does, but I went from AC plugs ( 44's, 43's, 42's gapped from .030 to .042) to Autolite 23's at .032 and my popping went away. Autolites worked for me! Heck, I am afraid to change my plugs cause I don't want to see popping again. Pop is gone 3 years now. My Mustang friends tighten theirs up to .025 all the time cause they blow the spark out. They run Superchargers. Their factory gap is like .060 or something......
 
Re: Plugz?/

Originally posted by Chuck Leeper
Tony, Reggie West had the same problem. I think he posted once he went from .032 to .025, no other changes, the car picked up a 100 HP on the dyno pulls.. back to back..

I have the DIS4-HO and run my plugs at .028.

HTH:cool: :cool:
Click to expand...

Yup, I'm seeing the faster guys run .025 to .028 as well. Most I know of run Autolite plugs as well.

Only thing I notices in *my* car, was a small gap like that, caused a rough idle. But my car aint no 8 sec car, and I dont like how it idled. That was with the stock ECM so 14.8 may have been too lean for such a small gap. I havent played recently, but Chuck's info sounds good to me.
 
I like NGK TR6 plugs better than the Autolite 103's. I can get 2 days at the track out of them where the 103's are done in a day.

Is your ground for the coil pack / module real good ? It's grounded through the mounting bracket.
 
Ok guys here is my take on this.Our car did gain 70 HP to the rear wheels just by changing the gap of the plugs from 35 to 25.I also use the NGK TR6 plugs and a DIS-4.The tuner was the one that suggested we do this and his reasoning was that the bigger turbos at higher purssures do blow out the spark of the plugs. At the time I was running a 72 turbo with a well worked over manifold and ported AL heads.Today it has a 80 BB turbo on it with the plugs gapped at 25 and I still drive it on the street 3 or 4 times a month.On my T Type I run A/C plugs with a 70 turbo and Champion Irons and I use the stock gap of 35 and the car runs 11.20 and is great on the street.

So what does all this mean? I guess the bottom line for me is that when you get to these real big turbos tighting the plug gap puts more ponies to the wheels at least thats what the dyno says about my car.

REG
 
Ok, now to answer some questions that I've seen. It isnt the MSD box causing the popping, because with the bypass adapter in on back to back dyno pulls, it still popped. As far as I know, the coil pack and module have a good ground, and the spark plug wires are in great condition. I've also heard alot of people say that you have to widen the gap with the DIS-4, then again, I've heard alot of guys say to tighten the gap to .025 or so, its just alot of mixed opinions, and frankly I dont know what to think. I dont wanna tell my dad to try the wrong thing and have it pop and blow another gasket. All I know is that with Autolite 103 plugs gapped at .035 with the MSD box bypassed, new coil pack and module, it still popped. Dont know what it is, but what like to find out
 
Are the wires spiral wound wire core or glass core? Spiral wound has less resistance more energy gets to the spark plugs.
 
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