poll: what plug gap do you run?

Beni · 07-09-2001, 02:21 PM

I know the norm is about .45-.55. I had mine at .54 forever, and while checking them I was bored, and decided to try an experiement. I opened them up to (your not gonna believe this) .75. Reasoning is, I have the Accel 300+ setup with good wires and autolite plugs. I figured the ignition was more than powerful enough to make the gap. BTW, this is an NA combo. Did a test drive and SOP is better low end with much quicker response. I will update with track times if I can ever make it back there... What do you guys think?

------------------
86GT bastard car w/83front,91 glass, 92 LX taillights, and a pile of parts
stock 86shortblock, stock cam, ported E7TEs, longtubes, and an attitude

93 Taurus SHO (stock)
jojo@gibralter.net

Capri306 · 07-09-2001, 09:31 PM

Sounds good, dude. Glad somebody else is still experimenting with spark plug gap for fun besides me.

The only thing I'd be afraid of is at higher revs, the coil might not have enough saturation time to fire such a wide gap, as it will require higher voltage for ionization. Rule of thumb is the higher the rev, the higher the required voltage but lower available voltage. Not many modern systems have any problems with it (the STOCK TFI-IV system has 50kV!), but with some extra juice from the Accel (haven't seen the numbers on that), opening the gap could be your ticket. This is especially true for N/A combos. Don't go too far, because the spark will actually get blown out like a candle at higher revs. Watch your distributor cap for carbon tracking and accelerated contact wear. Again, glad you found this out, too.

------------------
Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch

93CobraR · 07-09-2001, 10:36 PM

I'm running.060 with stock ignition. No problems with them yet.

------------------
87 GT, Cobra R's,GT-40 heads,Crane 2031,1.7's, Edelbrock intake, long tubes,BBK cold air, Mass air,pulleys,Pro 5.0, King Cobra,Lakewood Lift Bars,50/50's,subframes, 4.10's.
Best time 12.759
Best MPH 106.79
Best 60' 1.695

Visit my site at:
http://www.geocities.com/cobrar93_2000/MyPage.html

302 LX Eric · 07-10-2001, 08:26 AM

.054" with MSD Blaster 2 coil and MSD 6AL ingnition.

Now you got me thinking about opening it up a bit more....hhmmmmm

------------------
1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

Beni · 07-12-2001, 02:51 PM

well, due to the recent helocopter crash here, my excercise is postponed until Sat...so Ill be at T&T tonight! Ill post updates tommorow. Please keep the families of my 3 friends that died in your prayers.

------------------
86GT bastard car w/83front,91 glass, 92 LX taillights, and a pile of parts
stock 86shortblock, stock cam, ported E7TEs, longtubes, and an attitude

93 Taurus SHO (stock)
jojo@gibralter.net

exgmguy · 07-12-2001, 03:40 PM

What about nitrous guys??? I run a .035 gap on my Champion RC9YC's.
I am spraying only a 100 shot.

Beni · 07-13-2001, 02:02 PM

got results from the track...here it is...with no other changes in similar weather, opening the plug gap was worth 1.4 mph in the quarter. Here is the breakdown of my runs from my journal Im keeping. NOTE- the timing worked better at 10deg instead of 14deg (look at the mph) kind of unusual...my car developed starting problems once we fiddled with the timing, so I have to get it sorted out before I can verify it. Will be on the dyno 7/28.

6/21/01 adjust FP from 38psi to 40psi

RT .597
60ft 2.244
330ft 6.120
1/8 ET 9.203
1/8MPH 79.35
1/4 ET 14.071
1/4MPH 100.82

6/21/01 adjusted FP from 40psi to 42psi

RT .655
60ft 2.208
330ft 6.224
1/8 ET 9.348
1/8MPH 78.68
1/4 ET 14.224
1/4MPH 99.73

Opened spark plug gap from .54 to .75 (seat of pants is more low end, more responsive)

7/12/01 same as last run except .75 plug gap (similar weather) 20psi in Hoosiers

RT .551
60ft 2.273
330ft 6.133
1/8 ET 9.207
1/8MPH 79.49
1/4 ET 14.043
1/4MPH 101.64

7/12/01 back-up run

RT .708
60ft 2.235
1/8 ET 9.245
1/8MPH 78.93
1/4 ET 14.126
1/4MPH 101.13

7/12/01 Advanced timing to 14* lowered Hoosiers to 15psi (long burnout)

RT .504
60ft 2.066
330ft 5.873
1/8 ET 8.961
1/8MPH 79.10
1/4 ET 13.840
1/4MPH 100.72

7/12/01 same as above except lowered tires to 13psi (long burnout)

RT .480
60ft 2.052
330ft 5.910
1/8 ET 9.054
1/8MPH 78.54
1/4 ET 13.965
1/4MPH 100.26

Seems like it lost mph with the timing at 14*, had starter problems again and could not make any more passes

07-09-2001, 02:21 PM	#1
Beni Registered Member Join Date: Oct 1998 Location: Jacksonville, NC(station) and Tampa FL Posts: 37	poll: what plug gap do you run? I know the norm is about .45-.55. I had mine at .54 forever, and while checking them I was bored, and decided to try an experiement. I opened them up to (your not gonna believe this) .75. Reasoning is, I have the Accel 300+ setup with good wires and autolite plugs. I figured the ignition was more than powerful enough to make the gap. BTW, this is an NA combo. Did a test drive and SOP is better low end with much quicker response. I will update with track times if I can ever make it back there... What do you guys think? ------------------ 86GT bastard car w/83front,91 glass, 92 LX taillights, and a pile of parts stock 86shortblock, stock cam, ported E7TEs, longtubes, and an attitude 93 Taurus SHO (stock) jojo@gibralter.net

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07-09-2001, 09:31 PM	#2
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	Sounds good, dude. Glad somebody else is still experimenting with spark plug gap for fun besides me. The only thing I'd be afraid of is at higher revs, the coil might not have enough saturation time to fire such a wide gap, as it will require higher voltage for ionization. Rule of thumb is the higher the rev, the higher the required voltage but lower available voltage. Not many modern systems have any problems with it (the STOCK TFI-IV system has 50kV!), but with some extra juice from the Accel (haven't seen the numbers on that), opening the gap could be your ticket. This is especially true for N/A combos. Don't go too far, because the spark will actually get blown out like a candle at higher revs. Watch your distributor cap for carbon tracking and accelerated contact wear. Again, glad you found this out, too. ------------------ Capri306, Moderator, The Mustang Works Online 1979 Mercury Capri, 5.0L -- C4 -- 2.73 1987 Mustang LX Notch

07-09-2001, 10:36 PM	#3
93CobraR Registered Member Join Date: Oct 1999 Location: Cincinnati, Ohio Posts: 1,575	I'm running.060 with stock ignition. No problems with them yet. ------------------ 87 GT, Cobra R's,GT-40 heads,Crane 2031,1.7's, Edelbrock intake, long tubes,BBK cold air, Mass air,pulleys,Pro 5.0, King Cobra,Lakewood Lift Bars,50/50's,subframes, 4.10's. Best time 12.759 Best MPH 106.79 Best 60' 1.695 Visit my site at: http://www.geocities.com/cobrar93_2000/MyPage.html

07-10-2001, 08:26 AM	#4
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	.054" with MSD Blaster 2 coil and MSD 6AL ingnition. Now you got me thinking about opening it up a bit more....hhmmmmm ------------------ 1991 5.0 LX Coupe - 38,000 miles 13.17 @ 106.14 mph w/ 2.138 60'

07-12-2001, 02:51 PM	#5
Beni Registered Member Join Date: Oct 1998 Location: Jacksonville, NC(station) and Tampa FL Posts: 37	well, due to the recent helocopter crash here, my excercise is postponed until Sat...so Ill be at T&T tonight! Ill post updates tommorow. Please keep the families of my 3 friends that died in your prayers. ------------------ 86GT bastard car w/83front,91 glass, 92 LX taillights, and a pile of parts stock 86shortblock, stock cam, ported E7TEs, longtubes, and an attitude 93 Taurus SHO (stock) jojo@gibralter.net

07-12-2001, 03:40 PM	#6
exgmguy Registered Member Join Date: Feb 1999 Location: Utica, Michigan Posts: 2,631	What about nitrous guys??? I run a .035 gap on my Champion RC9YC's. I am spraying only a 100 shot.

07-13-2001, 02:02 PM	#7
Beni Registered Member Join Date: Oct 1998 Location: Jacksonville, NC(station) and Tampa FL Posts: 37	got results from the track...here it is...with no other changes in similar weather, opening the plug gap was worth 1.4 mph in the quarter. Here is the breakdown of my runs from my journal Im keeping. NOTE- the timing worked better at 10deg instead of 14deg (look at the mph) kind of unusual...my car developed starting problems once we fiddled with the timing, so I have to get it sorted out before I can verify it. Will be on the dyno 7/28. 6/21/01 adjust FP from 38psi to 40psi RT .597 60ft 2.244 330ft 6.120 1/8 ET 9.203 1/8MPH 79.35 1/4 ET 14.071 1/4MPH 100.82 6/21/01 adjusted FP from 40psi to 42psi RT .655 60ft 2.208 330ft 6.224 1/8 ET 9.348 1/8MPH 78.68 1/4 ET 14.224 1/4MPH 99.73 Opened spark plug gap from .54 to .75 (seat of pants is more low end, more responsive) 7/12/01 same as last run except .75 plug gap (similar weather) 20psi in Hoosiers RT .551 60ft 2.273 330ft 6.133 1/8 ET 9.207 1/8MPH 79.49 1/4 ET 14.043 1/4MPH 101.64 7/12/01 back-up run RT .708 60ft 2.235 1/8 ET 9.245 1/8MPH 78.93 1/4 ET 14.126 1/4MPH 101.13 7/12/01 Advanced timing to 14* lowered Hoosiers to 15psi (long burnout) RT .504 60ft 2.066 330ft 5.873 1/8 ET 8.961 1/8MPH 79.10 1/4 ET 13.840 1/4MPH 100.72 7/12/01 same as above except lowered tires to 13psi (long burnout) RT .480 60ft 2.052 330ft 5.910 1/8 ET 9.054 1/8MPH 78.54 1/4 ET 13.965 1/4MPH 100.26 Seems like it lost mph with the timing at 14*, had starter problems again and could not make any more passes