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Discussion Starter #1
My uncle and cousin race a dirt roundy round.
They did a rippin' 305 (yeah 305!) and put AC Delco plugs in. They ran it, and then started with a different carb, then distributor, to cure a stumble. Cousin says they changed to Bosch platinums, and it cured all.

The Elky has an off idle stumble (very slight at a LOT of timing advance, but there. Perhaps it could be as easy as indexing ANOTHER set of plugs, and throwing the R45TS's as far as I can?

Would LOVE these responses!!!!

Dave H.
Houston, (HOT!!!!) Texas
 

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If switching to a platinum plug solved their problem, it is likely that they have a poor ignition system. One major benefit of precious-metal plugs is that they have a lower voltage requirement than conventional plugs.
 

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There is, and have been how many millions of professionally built engines on the road using delco plugs without off-idle stumbles?

it was either luck or they were using fouled, or improperly gapped, or whatever, plugs... thats my opinion..

i just switched to delco R45T's and its running better than ever.

as for your stumble, check for vac. leaks and accelerator pump squirt, and sometimes idle mixture will affect that.. i run lots of initial timing on my el camino too ... how much are you talking exactly? what kind of carb, how old is it, etc...

Mike
 
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If I were you I would run right down to Pep Boys and buy some of those fine Champion plugs. You think AC are junk, hold on!

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Wally
Gold #67
67 malibu
 

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Dave,
I am currently running AC Delco Rapid fire plugs in all 3 rigs(Chevelle,burb,MC SS). No problems. They all start. No stumbles. Even on the burb when the temp sending unit for the computer died and the throttle body was p****ing fuel all I had to due once temp unit was swapped was wipe the plugs with a cloth and go.(That was 10k ago). I like 'em


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Jeff ACES#841 TCG#158
68 SS396(454)
68 L78 Project
87 MC SS



[This message has been edited by ACE841 (edited 08-11-99).]
 

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Dave,
I pretty much use AC plugs in everything, only because Wal Mart has them real cheap. I know everyone has thier favorites, and for every brand, there is someone with a bad story to tell, but to be honest with you, I cannot honestly say I have ever had a problem that I could absolutely blame on the MAKE of spark plug I was running. I have used Champions, NGK's Autolites, and AC Delco. Other than some of the no-name ones out there, I think they will all work fine. By the way, how many AC plugs do you think GM has used over the years

As far as your left turn motor, I think an R45 is probably too hot a plug for a race motor. I would have started with a 43 and worked from there.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100
 

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I used the Bosch's and felt a little less torque ( in a Buick 3.8). Of course it could have been due to the wider ( worn) gaps on the old plugs. The platinums do last longer. And Wally's right. Champions have been known to be junk since my teen age years in an auto machine shop. Nothing wrong with Ac's. And Autolite ( yes, I know the F word) are good plugs. The plug change changed something else. That's why it's called an ignition SYSTEM.
 

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After I built my engine I installed Champion spark plugs, only because Edelbrock recommended them. They worked just fine for 2 weeks, then I spent the next 2 weeks chasing a 6000 rpm break-up. I finally decided to change plugs to AC, no problems since.BTW, heat range was the same and it's been 6 weeks since the AC's were installed.

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Joe Giniel
72 Chevelle SS
Team Chevelle #143
Aces #03056
 

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Since we are talking about plugs i was wondering if you guys could help recommend a plug for my 327. Heres the combo. 327 bored .030, hyp pistons, 461 heads w 2.02/1.60 and 3< valve job. GM 4v with a Q-jet. Cam is the small one from factory, .390/.410 valve lift,small duration and the such. Stock points distr. to. Thanks

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68chevelle, put the stock AC plugs in, AC44 or 45. Run those and see how things go. I chased plugs in my Z/28 and ended up using AC 44 or the same plug in Autolite.

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Wally
Gold #67
67 malibu
 

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I used a-c s all my life,never let me down.I learned not to blame spark plugs for another problem.autolites I like also.tryed splitfires in my bike,no gain.bosch? good plug,but I keep going with a-c delco.because they always performed the best.champions? those are for lawn mowers.
good day,all 67rat member #199
 
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Lawnmowers, weed whackers, chipper shreaders and Chrysler products.

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Wally
Gold #67
67 malibu
 

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Discussion Starter #13
Oh MAN, I knew this would be good!
OK, our motor ain't no roundy rounder, it's a streeter. 350 + .060, BIG dished (deep dished) two valve TRENCH pistons. 64cc 1.94 heads, CR??? I think 8.5 or so. Performer intake and cam, 204/214 @.050 and .420/.446 with 1.5 roller rockers. And a supposedly pro rebuilt Vette Qjet.
Pump shot seems ok, stock dist. with a curve kit, and a hot coil (can't remember brand just now, buddy at speed shop said it's a good one.
I don't have exact TDC marked (very close) and initial timing is at about 25 advance (backed off a bit from 28 or so due to start problems. I kinda think the carb is crapped out...been reading carb posts with interest! Our 'Burban had an AFB on it. I never touched it, and it always ran good...so I lean towards AFB/Edelbrock.

So should I be on cooler plugs? or hotter?

Dave H. (brain dead Dave)
Houston

OH...mildly hogged out stock manifolds to 2 1/4 dual glasspacks (YUCK!...<got it that way and can't afford to change it just now> ) Headers are in the future as well.

[This message has been edited by 81ElCamino (edited 08-11-99).]
 

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I have a '72 402 (stock) and had good luck with AC R45TS. The Bosch platinum seemed to foul quicker. I plan to add an Edelbrock performer intake, cam along with a head job. Any suggestions on what plug to start with?
 

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In 21 years in a GM service department, I've seen countless poor running cars fixed by switching to AC plugs. I don't know why, but the results speak for themselves. I always liked installing them in front of the customer who thinks that no way will plugs fix this problem. I have told them if this doesn't fix it, the plugs are free. I have yet to give away a set! Autolite are good also. SSuper Dave

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Wally, from what i have been told with the smaller cam it will build more cylinder pressure. Is this correct or not? and if so will a colder plug help prevent denotation? If that is the case is the 44 or the 45 colder? Thanks

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I was told, and cannot verify, that AC, Champion and most others use furnace cement to seal the inside of the plug. Autolite uses ceramic to seal it. I don't know if it means anything.

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Pat Kelley
66 & 67 El Caminos
 
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The 44 is the colder of the two. Don't get caught up in the pressure deal. My Z car was an NHRA stocker, one of the crazy cams from Lunati. Ran stock AC plugs.

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Wally
Gold #67
67 malibu
 

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I'm not a sparkplug expert but the Champions seen to protrude deeper into the cyl. then the AC's and this seems to make them foul out easyer on a motor with high miles or wear. I switched to AC's on my 396 and it seems to like them. Also the heat ranges are not exactly the same from one brand name plug to another even though it is the right plug for the same application.
 

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AC Delco has the most warranties of any plug, but that might be because they probably sell the most plugs.
I used to run a R46TS in the old worn out 307 and kept 8 extra on hand when the 8 in the motor got fouled; I would take them out put the others in and clean the old ones and put them back in when the new ones got bad. This would work for about four times before the diode went completely bad.
 
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