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Author
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Topic: Spark plugs which ones and what gap??
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-18-2002 04:55 PM
 
I have been using the autolites#42 with a gap of 35.
Is there a better plug for me and or gap.I have had real good luck with my set up now.My car always fires right up.I do use some oil,and get some on the plugs.
SCOOP
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65 coupe,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-19-2002 02:14 PM
Hey I'm sorry to bug you guys with this question.But do any of you have any input.  SCOOP ------------------
65 coupe,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Moneymaker
Administrator Posts: 29200
From: Lyons, IL, USA
Registered: May 99
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posted 04-19-2002 02:23 PM
Are you certain about that number Scoop? 42's?  ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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Butch Jennings
Gearhead Posts: 637
From: No. California
Registered: Apr 2000
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posted 04-19-2002 02:26 PM
42's are cold, cold, cold! When I ran an FE in my car I ran 32's (non-resistor) when I ran nitrous and 33's when I raced it on the motor. I always ran 34's on the street....44's would be the resistor equivalent of a 34. I just saw that you said it uses oil....I'd use a 45 in it if that's the case.
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Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
[This message has been edited by Butch Jennings (edited 04-19-2002).]
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-19-2002 02:28 PM
Alex now I'm not certain of the 42's.
Heck I cant remember what the dam plug number is now.I think it is 44?SCOOP ------------------
65 coupe,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
[This message has been edited by Fastymz (edited 04-19-2002).]
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-19-2002 04:38 PM
I'll try the #45,
and gap then at 35 or less???Dose it matter that my motor is a 351w? SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Butch Jennings
Gearhead Posts: 637
From: No. California
Registered: Apr 2000
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posted 04-19-2002 06:00 PM
I'd gap them at .030".------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-19-2002 07:20 PM
Thanks Butch,I'll try the #45 and gap them at .030.SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Moneymaker
Administrator Posts: 29200
From: Lyons, IL, USA
Registered: May 99
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posted 04-19-2002 08:03 PM
Ditto. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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70 Pony
Gearhead Posts: 2366
From: West Chester, PA, USA
Registered: Jan 2000
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posted 04-20-2002 04:55 PM
I know this is a dumb answer...but doesn't it depend on what heads you are running...
My TFS heads call for autolite 3924's....but I like the 23's better (one step colder)and gap them around 36.....
Doesn't your ignition set up "regulate" your gap...e.g. hotter ignition...bigger gap..???
This doesn't answer your question I guess SCOOP....
But as usual I am confused....------------------
EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red
'02 GT, Torch Red
"If I knew I would have lived this long, I would have taken better care of myself !"
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-20-2002 07:33 PM
quote:
Originally posted by 70 Pony:
I know this is a dumb answer...but doesn't it depend on what heads you are running...
My TFS heads call for autolite 3924's....but I like the 23's better (one step colder)and gap them around 36.....
Doesn't your ignition set up "regulate" your gap...e.g. hotter ignition...bigger gap..???
This doesn't answer your question I guess SCOOP....
But as usual I am confused....
These all good questions, This is why I set my gap wider.When I installed a pertronix ingnitor and coil.The insructions said to increase plug gap.
"Doesn't your ignition set up "regulate" your gap...e.g. hotter ignition...bigger gap..???" SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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70 Pony
Gearhead Posts: 2366
From: West Chester, PA, USA
Registered: Jan 2000
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posted 04-21-2002 03:31 PM
Well Scoop....let's hope somebody reads this and answers our question...like you I read...install so and so and widen your gap..but they never say how much.... ------------------
EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red
'02 GT, Torch Red
"If I knew I would have lived this long, I would have taken better care of myself !"
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Butch Jennings
Gearhead Posts: 637
From: No. California
Registered: Apr 2000
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posted 04-21-2002 07:18 PM
I can only speak from my experience and what I know has worked for my combination. I've tried running my plug gaps everywhere from .060 down to .020. I've found that even with my MSD7al-2 ignition, with a Pro Power coil, it runs best at .025....and you won't find many ignition systems that have more power to light a spark plug. I think that when GM came out with the HEI and cars were setup to run a leaner a/f mixture is when the "bigger is better" thinking on plug gap started....at least that's when I remember the plug gaps started to grow. I think of it in these terms, in a leaner a/f mixture there are fewer fuel molecules in a given amount of space, so the larger plug gap allows more fuel "in the gap" of the plug to be ignited. I don't think that it is an issue with a richer or more normal a/f mixture and the smaller gap allows for a better spark with the same amount voltage. I may be off base with my reasoning as to why it works, but for me the timeslips don't lie....my car, my combination works best with the plug gap at .025. ------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys" [This message has been edited by Butch Jennings (edited 04-21-2002).]
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-21-2002 07:23 PM
Butch if it works for you then it must be right. Thanks
SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-21-2002 08:51 PM
One of the things that make one plug better than another and increases the need for a better ignition system is cylinder pressure, a poor plug or weak system won't fire an engine with high operating pressure. I always laugh when I see a display with a 4" stream of blue flame showing how great a given ignition system is, because if that display were put in a pressurized container you could watch the flame die as the pressure goes up, as it would be in an engine. Also an engine that turns more Rs has less time to build a good coil load of juice so X% of a killer spark is better than X% of the stock spark in that instance as well.
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-22-2002 01:45 AM
I took out some of my old plugs.#1and 8
They are #45 gapped at .045.I'll get a new set and gap then at .030.My old plugs both had oil on the treads,but the tips and porcelin and tips were clean.The porcelin was mostly white with a slight tan to it.And the tips had a small area of tan as well.
Larry I think your saying run a smaller gap.It will burn better.
SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-22-2002 02:39 AM
The post was supposed to explain to 70 Pony the reasoning behind tricker systems isn't to be able run wider gaps but to fire the plug better with the conditions we create in hot rodding. I'm just naturally vague 
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70 Pony
Gearhead Posts: 2366
From: West Chester, PA, USA
Registered: Jan 2000
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posted 04-22-2002 04:44 PM
Thanks Butch and Larry...like a dope, I always figured the bigger the gap, the more spark...point to point.....
Gonna close 'em up...man 25 seems razor thin.....
Guess I'll try the old Ford spec...32....
Thanks all....------------------
EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red
'02 GT, Torch Red
"If I knew I would have lived this long, I would have taken better care of myself !"
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 04-23-2002 02:09 AM
quote:
Originally posted by Larry Jennings:
The post was supposed to explain to 70 Pony the reasoning behind tricker systems isn't to be able run wider gaps but to fire the plug better with the conditions we create in hot rodding. I'm just naturally vague
Larry thats how I took it.I was not being smart with you.I was just restated what you said.
Thanks for the help. SCOOP ------------------
65 coupe,351w,C4,Big Boss 429 hood scoop,Crager SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-23-2002 02:53 AM
We're cool Scoop. I didn't think you were pickin on me . I just realized after reading the post it's rather vague and since I wrote it I'm rather vague LOL!
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 04-23-2002 03:08 AM
I don't want to rock the boat, but when I recently installed a MSD 6A in my 69 Cutlass,I left the original plugs gapped at .030 in and I noticed that it was starting to misfire over 5000 rpms. I pulled the plugs out and noticed that the tip looked like it was starting to melt and the insulator had grey spots on it. I gapped the plugs to .070, the misfire went away and the plugs began to look normal again. Does this mean that when using a high energy ignition, that you need to run a colder plug??
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Butch Jennings
Gearhead Posts: 637
From: No. California
Registered: Apr 2000
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posted 04-23-2002 09:29 AM
quote:
Originally posted by bluestreek:
I don't want to rock the boat, but when I recently installed a MSD 6A in my 69 Cutlass,I left the original plugs gapped at .030 in and I noticed that it was starting to misfire over 5000 rpms. I pulled the plugs out and noticed that the tip looked like it was starting to melt and the insulator had grey spots on it. I gapped the plugs to .070, the misfire went away and the plugs began to look normal again. Does this mean that when using a high energy ignition, that you need to run a colder plug??
Sounds like a lean condition to me.
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Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 04-24-2002 06:00 PM
You may be right, cause I installed headers at the same time, and also put a quick curve kit in the distributor. It picked up 1/2 second and 5 mph in the 1/4 mi. Gottsa need more fuel for all that. Thanks PS: Sorry for mentioning an Olds. 
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-24-2002 10:02 PM
Butcher has had a couple of "Oldmobiles" .------------------
I got this black eye when my wife said shut up and I thought she said get up!
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