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Before I read in the forums that Boschs were bad, I bought a set, and had GM install them w/ new wires. I currently have Bosch +4's in car with about 100 miles on them if that. They are much better than the AC's that were in the car, but I have read that platinums aren't good with this car. AC's make them, so should I avoid those too? Some have said to use Iridiums, and that AC makes them for this car, but their website does not list them for my 91 yet. I would like to get a good plug that will last a long time with no fouling or poor cold engine performance (boschs appear to possibly have this problem) I would rather not have to replace the cheapo AC's every 30K but I will if I have to if its the best for this engine.
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1992 Grand Prix SE 3.1l 155k SOLD
1992 Grand Prix GTP 3.4l 55K
1991 Grand Prix GTP 3.4l 5 speed 99K SOLD
1988 Pontiac Fiero GT 2.8 5 speed Turbo 36K Sold
2011 Mazda 3s 5dr 6 speed
2008 Grand Prix GXP 5.3l 24K sold -
Just have the parts store look up Iridiums for a newer 660. Spark plug hole size/threads/depth is all the same on the 660 family.-60v6's 2nd Jon M.
91 Black Lumina Z34-5 speed
92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
94 Red Ford Ranger 2WD-5 speed
Originally posted by Jay Leno
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I disagree. Think the best plug I came w/ the DOHC engines is the Torque master plug.
If you can fab up some custom spark plug wires from MSD (w/ a low ohm rating), and wiring in A MSD DIS-2 spark box in there, then get the S-plugs from torquemaster. Watch youre throttle response go crazy.
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whatever you decide to go with i would stick to either NGK or AC Delco plugs... even the newer OE plugs from GM are NGK's. something to be said if GM is using them stock.
SShane "RedZMonte"
2004 Corvette Z06 Commemorative Edition -VIRGIN
1995 Monte Carlo Z34 14.38@101mph, 331hp/355tq
-Turbonetics T04E Super 60 Turbo, 2.5" Borla Catback, OBDII, 42.5# Injectors
2004 Subaru WRX STI -Lightly Modded (SOLD)
1994 Lumina Z34 -VIRGIN (SOLD)
1992 Lumina Z34-VIRGIN (RIP)
1992 L67 Lumina Z34 (SOLD)
1990 Turbo Grand Prix (SOLD)Comment
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Yo, red monte,
I highly disagree. I've tried them all. Their was a new and improved GM plug (can't remember the name), Ive tried regapping the Splitfire plugs, NOTHING amps up that throttle response in a DOHC engine like that Torquemaster Splug. That's assuming the
ignition can jump the extra plug gapp on those plugs. I Don't know what the stock plug
gapp on those DOHC 3.4 engines are.Comment
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i have a 95 mc z34 with 3.4dohc has 111,000 on it i run rapidfire plugs no problemComment
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I've been running Bosch platinum + 4 for three years with no problems... A few IC module issues and a dead CP sensor but plugs are fine.1991 Pontiac Grand Prix GTP / 3.4 DOHCComment
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Reply 2 Robertstar
Sirs,
The splitfire S plug is equivalent to a .060s plug gapp. That's why a spark box needs to be run with it. Someone said that their using a platnum plug
in their Dohc v6. I had a problem w/platinum plugs in a DOHC quad 4. Be careful, I ended burning a hole in my header because I wasn't burning all of
the air/fuel mixture in the combustion chamber. All of those problems went away with the S plugs. They say their plugs w/last the life of the car.Comment
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I've run the #8's for years without a problem as well. I was told that they weren't in the right heat range though, and they tend to leak compression where the ceramic meets the metal so I was considering switching to NGK this year after having good results with them in customer cars.Originally posted by tommyz34 View Post-60v6's 2nd Jon M.
91 Black Lumina Z34-5 speed
92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
94 Red Ford Ranger 2WD-5 speed
Originally posted by Jay LenoComment
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Our waste spark system tends to trash Bosch plugs in a short amount of time because of the way it works. I bet you would be surprised if you put a different set of plugs in it.Originally posted by GTP091 View Post-60v6's 2nd Jon M.
91 Black Lumina Z34-5 speed
92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
94 Red Ford Ranger 2WD-5 speed
Originally posted by Jay LenoComment
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Yup. Plus they are not usually the correct heat range for the car.
I replaced my friend spark plugs in his Jeep cause it was running bad, guess which ones they were? And guess what happened to 2 of the plugs? Ceramic shattered off... Hope his engine spit them out without chewing on them or getting caught in a valve... I wonder if they were the wrong heat range and messed up because of that? Usually though I think they are too cold...
But yes you need double platinum plugs with waste spark DIS.sigpic
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1994 3100 BERETTA. 200,000+ miles
16.0 1/4 mile when stock. Now ???
Original L82 Longblock with LA1, LX9, LX5 parts
Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.
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plugs
i can only speak for myself, i had 2 z34's i just bought another one 2 months ago, and just picked up a 95 gp gtp. i have always used the bosch +4 plats. i never had a problem with them at all, i had cheap AC DELCOS at one point, i find the car wont idle as good as the plats. also along with good coil packs by MSD with taylor's 8.4 mm wire. this is what i have, you might wanna try this set up, it's all prefference bud,Originally posted by Cidacious View Post
In a quiet town full of chevy's, you can hear a FORD rust.Comment
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so what plugs do you guys use?In a quiet town full of chevy's, you can hear a FORD rust.Comment
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read the previous posts to find out. (the two pages before your comment)Originally posted by z34gtp383 View PostComment
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