advice - cut back rapidfire #5's?
Thread Starter
Instructor
Joined: Apr 2001
Posts: 197
Likes: 0
From: Mechanicsburg PA
advice - cut back rapidfire #5's?
i just got some rapidfire #5's for my 90 L98. would it be a good idea to cut back the electrodes?
also, i checked the gap on the #5's and they're set at about 0.043. Stock gap for our 90 is 0.035. Do you think we should change the gap to 0.035?
thanks!
also, i checked the gap on the #5's and they're set at about 0.043. Stock gap for our 90 is 0.035. Do you think we should change the gap to 0.035?
thanks!
Race Director
Joined: May 2003
Posts: 10,749
Likes: 41
Re: advice - cut back rapidfire #5's? (psuvette)
just installed mine and left gap at .043, and i love them compared to my old delco's!! how much did they cost you?
p.s. how are your injectors? any problems ever?
p.s. how are your injectors? any problems ever?
Racer
Joined: Jun 2001
Posts: 422
Likes: 0
From: Berrien Springs MI
Re: advice - cut back rapidfire #5's? (psuvette)
I used to cut back the electrodes in my 95 but didn't notice a difference. I know narrowing the gap will make the exhaust resonance louder. Really! BH
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: advice - cut back rapidfire #5's? (honas)
Not sure if these plugs have the disc's on the ground electrode or not. If so, you will cutting off the disc. Some complain of the disc falling off anyway.
If you do loose the disc, I'd suggest you gap them .005" closer. You will loose that much as the plugs wear in.
If you do loose the disc, I'd suggest you gap them .005" closer. You will loose that much as the plugs wear in.
Thread Starter
Instructor
Joined: Apr 2001
Posts: 197
Likes: 0
From: Mechanicsburg PA
Re: advice - cut back rapidfire #5's? (88BlackZ-51)
I got mine for 4 bucks a pop at autozone. That was a bit cheaper than the 6.25 that zip wanted for them.
Yea, I noticed that the tip of the plug is pointed. Is that the puck that people complain about coming off? Anyway, should I cut back the plugs or not?
88zr1 - yes, i did have trouble with my injectors. its a long sordid story that cost us a lot of money. the coils in the injectors were shorting out (both hot and cold - watch that though..injector resistence may be fine when cold but falter when hot), and we needed to replace a few.
[Modified by psuvette, 1:19 PM 9/8/2003]
Yea, I noticed that the tip of the plug is pointed. Is that the puck that people complain about coming off? Anyway, should I cut back the plugs or not?
88zr1 - yes, i did have trouble with my injectors. its a long sordid story that cost us a lot of money. the coils in the injectors were shorting out (both hot and cold - watch that though..injector resistence may be fine when cold but falter when hot), and we needed to replace a few.
[Modified by psuvette, 1:19 PM 9/8/2003]
Burning Brakes
Joined: May 2002
Posts: 986
Likes: 99
From: Collegeville PA
Re: advice - cut back rapidfire #5's? (psuvette)
psuvette, I posted the same question a while ago. Take a look, it should be very helpful. http://forums.corvetteforum.com/zerothread?id=340579
*I remember the car running a little rough with the larger gap, so I took them out and put in a set of AC Delco "Cut plugs" gapped at .035 and it ran smooth as could be. You'll notice a bunch of scenarios like this in the linc, but it sounds like every car is different. If I were you, I'd run them "as is" for a week or 2, then re-gap them and compare the difference. I did this about 5 times in 2 weeks until I was happy.
Good Luck :flag
[Modified by Triple Black 88, 1:38 PM 9/8/2003]
*I remember the car running a little rough with the larger gap, so I took them out and put in a set of AC Delco "Cut plugs" gapped at .035 and it ran smooth as could be. You'll notice a bunch of scenarios like this in the linc, but it sounds like every car is different. If I were you, I'd run them "as is" for a week or 2, then re-gap them and compare the difference. I did this about 5 times in 2 weeks until I was happy.
Good Luck :flag
[Modified by Triple Black 88, 1:38 PM 9/8/2003]
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Verdad Gallardo
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: advice - cut back rapidfire #5's? (Triple Black 88)
If you are running the stock ignition setup I wouldn't run the gap wider than .035".
If a plug has a pointed center electrode it may work well at .043" initially but will likely give problems as the point wears off and the spark has trouble igniting the mix at the wider gap.
A hotter setup (like the HyperTech) provides substantially higher voltage to ignite the charge across as much as a .045"-.050" gap.
For those who have tried the cut-back electrodes, don't expect to "feel" that 8-10chp gain, but do check it out at the track or on the dyno. If at the track, be sure to compare trap speeds after normalizing for weather as variations there can mask effects of mods.
If a plug has a pointed center electrode it may work well at .043" initially but will likely give problems as the point wears off and the spark has trouble igniting the mix at the wider gap.
A hotter setup (like the HyperTech) provides substantially higher voltage to ignite the charge across as much as a .045"-.050" gap.
For those who have tried the cut-back electrodes, don't expect to "feel" that 8-10chp gain, but do check it out at the track or on the dyno. If at the track, be sure to compare trap speeds after normalizing for weather as variations there can mask effects of mods.
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: advice - cut back rapidfire #5's? (psuvette)
AC Delco recommends a .045 gap for the AC Rapidfire #5 installed in a '90 L98. The Rapdifire's already feature some advanced engineering and work great out of the box-- don't try to re-invent the wheel with them, use them gapped .045 or .043 (close enough) out of the box. Standard plugs probably benefit far more from cut back ground straps than a Rapidfire would. You would only be shrtening the life of an already expensive plug.
P.S. to zylarace, Rapidfires do not have the pucks like the AC professional platinum's (AC 41-902, 41-906, 41-943 etc). They have a platinum tip firing electrode but the ground strap is a nickel-silver alloy and has no pads welded on it.
[Modified by Lone Ranger, 5:03 PM 9/8/2003]
P.S. to zylarace, Rapidfires do not have the pucks like the AC professional platinum's (AC 41-902, 41-906, 41-943 etc). They have a platinum tip firing electrode but the ground strap is a nickel-silver alloy and has no pads welded on it.
[Modified by Lone Ranger, 5:03 PM 9/8/2003]