Understanding Backfire - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SuperCheyenne72 · 05-28-2008, 03:06 AM

Long story short,

I just recently replaced my stock AC Delco sparkplugs with some "slightly used" (longer story) Splitfire plugs. In order to prep and clean my Splitfire plugs a bit, I used some WD40 and some Carb and Throttle Cleaner. I then gapped the Spitfire plugs to match exactly what the ACDelcos were at.

I pop all 8 in, and try to fire it up... it takes a while but doesnt catch. After pumping a few times it finally catches, but VERY rough... only to POP loudly and die. This goes on a few more times but never gets better.

Finally I decide to just replace the old ACDelco plugs back in.. and sure enough, it fires right up, with no problems.

So what caused the backfiring? Could it have been the slight moist residue from the Carb cleaner fluid still in the "spark zone" of the Splifires? Or could this have happened if one or two plug cables were not "snapped" in all the way?

Steelawork'n · 05-28-2008, 03:29 AM

I've heard the Splitfires are not all they're cracked up to be.

mvfd70 · 05-28-2008, 04:17 AM

I've heard the same thing about the splitfire plugs. I've had mechanics and parts store guys tell me that OE is better than they are

SuperCheyenne72 · 05-28-2008, 04:47 AM

Well to be frank, I've run Splitfires for quite some years now and this is the first time this has ever happened to me. But this IS also the first time I've ever tried a gap of .050 as opposed to my normal .034 gap. I went to the bigger gap because a mechanic suggested I had to do so since I have such a hot running HEI distributor.

While on the subject of plugs, has anyone heard of these, or tried em?
http://www.pulstarplug.com/

ed2552 · 05-28-2008, 04:50 AM

I've heard good stuff about the E3 plugs, but never tried them. May try them on my new car

jeffspower · 05-28-2008, 04:59 AM

I haven't heard anything good about the Splitfires, or Bosch. I put AC Rapidfires in my truck back around '96. Still in there today & I've never pulled one. Granted, I've only put about 13K miles on them, but they have been trouble free.

Myself · 05-28-2008, 04:59 AM

Sounds to me like a couple of them are no good. Take an ohm meter to them and see what they read out.

Longhorn Man · 05-28-2008, 05:08 AM

the .050 gap may well have been the problem too.
I've run them, and on a small engine, there was a huge improvement in MPG, and a bit in performance measured by a G-tech thing.

05-28-2008, 03:06 AM	#1
SuperCheyenne72 Registered User Join Date: Dec 2001 Location: Dallas, TX USA Posts: 80	Understanding Backfire Long story short, I just recently replaced my stock AC Delco sparkplugs with some "slightly used" (longer story) Splitfire plugs. In order to prep and clean my Splitfire plugs a bit, I used some WD40 and some Carb and Throttle Cleaner. I then gapped the Spitfire plugs to match exactly what the ACDelcos were at. I pop all 8 in, and try to fire it up... it takes a while but doesnt catch. After pumping a few times it finally catches, but VERY rough... only to POP loudly and die. This goes on a few more times but never gets better. Finally I decide to just replace the old ACDelco plugs back in.. and sure enough, it fires right up, with no problems. So what caused the backfiring? Could it have been the slight moist residue from the Carb cleaner fluid still in the "spark zone" of the Splifires? Or could this have happened if one or two plug cables were not "snapped" in all the way? __________________ '72 Super Cheyenne LWB 350 V8 w/ TH400 MSD Pro Billet HEI Dist. w/ Splitfire plugs Edelbrock Performer Intake Manifold and dual exhuast glasspaks Edelbrock Performer 750 cfm

05-28-2008, 03:29 AM	#2
Steelawork'n Just hang'n around Join Date: Nov 2005 Location: Camano Island WA Posts: 248	Re: Understanding Backfire I've heard the Splitfires are not all they're cracked up to be. __________________ Driving a '68 Chevy C20 and a '93 Astro Van. Lots and lots of mileage that I deduct each year.

05-28-2008, 04:17 AM	#3
mvfd70 Registered User Join Date: Jan 2007 Location: Opdyke, IL Posts: 775	Re: Understanding Backfire I've heard the same thing about the splitfire plugs. I've had mechanics and parts store guys tell me that OE is better than they are __________________ 1978 Chevrolet Silverado 3/4 ton 400 small block. 2000 F-250 Powerstroke 2002 GMC Yukon Denali XL

05-28-2008, 04:47 AM	#4
SuperCheyenne72 Registered User Join Date: Dec 2001 Location: Dallas, TX USA Posts: 80	Re: Understanding Backfire Well to be frank, I've run Splitfires for quite some years now and this is the first time this has ever happened to me. But this IS also the first time I've ever tried a gap of .050 as opposed to my normal .034 gap. I went to the bigger gap because a mechanic suggested I had to do so since I have such a hot running HEI distributor. While on the subject of plugs, has anyone heard of these, or tried em? http://www.pulstarplug.com/ __________________ '72 Super Cheyenne LWB 350 V8 w/ TH400 MSD Pro Billet HEI Dist. w/ Splitfire plugs Edelbrock Performer Intake Manifold and dual exhuast glasspaks Edelbrock Performer 750 cfm

05-28-2008, 04:50 AM	#5
ed2552 Registered User Join Date: Jan 2007 Location: Charles City IA Posts: 1,626	Re: Understanding Backfire I've heard good stuff about the E3 plugs, but never tried them. May try them on my new car __________________ '67 C20, Under the Knife!, LWB, Eaton HO-52, Rear Coil Springs 72' GMC C2500, 350, TH400(?), Dana 60 '67 K10 4-spd., 305, SM465, Dana 44, 12 Bolt, RUST! '65 C60 292, 4 spd, 2 spd Rearend, 15' Grain Box, MINT! 09 Yukon Denali 82k Miles 6.2L/6A

05-28-2008, 04:59 AM	#6
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	Re: Understanding Backfire I haven't heard anything good about the Splitfires, or Bosch. I put AC Rapidfires in my truck back around '96. Still in there today & I've never pulled one. Granted, I've only put about 13K miles on them, but they have been trouble free. __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

05-28-2008, 04:59 AM	#7
Myself Registered User Join Date: Oct 2005 Location: Northern Arkansas Posts: 1,131	Re: Understanding Backfire Sounds to me like a couple of them are no good. Take an ohm meter to them and see what they read out.

05-28-2008, 05:08 AM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Understanding Backfire the .050 gap may well have been the problem too. I've run them, and on a small engine, there was a huge improvement in MPG, and a bit in performance measured by a G-tech thing.



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