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View Poll Results: Which Brand of spark plug you run? | |||
Autolite |
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3 | 2.13% |
AC-delco |
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66 | 46.81% |
Accel |
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1 | 0.71% |
E3 |
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4 | 2.84% |
Champion |
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0 | 0% |
Bosch |
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11 | 7.80% |
Brisk |
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0 | 0% |
Torque Master |
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1 | 0.71% |
Motorcraft |
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0 | 0% |
NGK |
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45 | 31.91% |
Pulstar |
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0 | 0% |
Splitfire |
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1 | 0.71% |
Denso |
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9 | 6.38% |
Voters: 141. You may not vote on this poll |
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#31 | |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 899
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![]() Quote:
I don't know what change made that possible. As to why the bigger gap, I bet Behan probably knows for sure, but I bet it was to improve idle stability and idle emissions.
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 |
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#32 |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 899
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![]() Sheesh that's a hot spark plug. I wonder why he recommends that?
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 |
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#33 | |
![]() Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 523
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![]() Quote:
Not sure if I remember correctly with that but it sort of makes sense. Can anyone confirm? Or am I wrong? Sent from my SM-G991B using ZR-1 Net Registry mobile app
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ZR-1 #638/1991 Last edited by Matt B; 08-07-2021 at 02:57 PM. |
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#34 |
![]() Join Date: Jan 2021
Location: Seattle
Posts: 28
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Just installed Denso IT20TT plugs as per a recommendation by Marc I found on the forums. Gap 0.045". I was aiming for an NGK 6 heat range equivalent plug as I'm mostly street driving with an occasional pull. They're an iridium/platinum electrode plug - supposedly ideal for wasted spark ignitions. This was my first plug change since acquiring my Z this year - the AC Delco 41-963's were crusty (due to moisture?) and had worn to about 0.053" except one, which was about 0.037" (dropped before install?). Runs noticeably better now.
Plug 8 was much easier to get at than I expected - below is the combination of tools I used to get at the plug. The aluminum welding wire was used to separate the plug socket from the short extension, magnet used to remove the socket and extensions from the hole. Last edited by ImpalaDave; 09-26-2021 at 09:57 AM. |
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#35 |
Join Date: Apr 2009
Location: ITALY
Posts: 264
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Bosch FR7DC+ 0.9gap
I'm in Italy |
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#36 | |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 899
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![]() Quote:
Starting maybe 20 years ago, on the ZR-1 Net mail list and later on this forum, I evangelized the advantages of the Denso IT20, hotter coils and opening up the plug gaps to .045-.050. While I convinced a few folks of the Denso 20 heat range's merits, at the time, not a lot of folks tried that. Now, even Marc is suggesting the IT20TT which is basically the same plug but with two, rather than just one Iridium tip. After I had the late Jim Van Dorn's Automasters, build me a 500-hp "Street Skinner" engine, I went yet another range colder to the IT22. That worked very well for just about any driving I did, except for chassis dyno development, when I would install a set of IT24s. Today, I still use the Denso Iridium Power IT22 in an LS6, an LS7 and the 2G LT5. Denso, at least so far, does not make an IT22TT or I'd use that. And, yes, the 405-hp engines used a double platinum tipped, conical seat spark plug whereas the 375-hp engines used a conventional-tipped, flat seat spark plug. Interestingly, the plug for most production engines was an AC FR2LS which was a very late change. Originally, the plug was going to be the AC FR1LS, which for the time, was a very cold plug, but some issues with "pre-delivery fouling" with very early 1990 cars, had GM going one range hotter to solve that problem. The AC 1 heat range was about the same as the NGK 6 and Denso 20 heat ranges. Another interesting tidbit was that all early LT5 heads manufactured by Brimal were machined such that the flat seats for use with spark plugs having sealing washers could be converted to conical seats for plugs with "tapered seats" simply by installing the taper seat plugs with a one-time "over-torque" procedure which cold-formed the conical seats in the head allowing use of taper seat plugs which in most cases provide a more reliable and durable compression seal. Ain't these look at how it was back in the early days of the C4 ZR-1 hobby just too much freakin' fun? ![]()
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 Last edited by Hib Halverson; 03-16-2022 at 07:24 PM. |
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#37 |
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,697
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I am using same only gapped at .035?. I did try the
NGK BKR5E-11 which come gapped at .044? but motor seems to operate smoother at .035?. My LT5 has had porting by Pete along w his Stage 2 cams. FYI, no knock retard to speak of.
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[SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX |
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#38 |
![]() Join Date: Feb 2011
Location: Clayton, North Carolina
Posts: 1,133
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Lou[COLOR="Red"][B][SIZE="4"][/SIZE][/B][/COLOR] |
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