|
Ignition Guru's - Spark Plug Gap to .040" or not?
#1454935
06/18/13 06:35 PM
06/18/13 06:35 PM
|
Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Guys, I have a question for any ignition gurus in here about maybe gapping my plugs out to 40 thousands (from the 35 now). I am thinking to realize the higher spark energy of my Blaster II coil, I will need to increase the gap. I have tested the output of the coil and it hits 40-45kV consistantly at the wires with a spark plug tester. If the OEM coil was outputting closer to 25-30kV, wouldn't I gain a hotter spark by gapping out a bit? Here is the specs on what I am dealing with: - Mopar 'chrome' ECU with MSD blaster II coil + .5 ohm ballast - Mopar Performance distibutor - Moroso 8.8mm blue wires - Champion spark plugs @ 35 gap - 400>>499 stroker 10.4:1 compression and Eddy RPMs Car runs, fine....I am just wondering if it would run better (smoother idle, etc) if I gapped out or am I asking for trouble? Thanks! 
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: cjskotni]
#1454936
06/18/13 07:16 PM
06/18/13 07:16 PM
|
Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick
master
|
master
Joined: Mar 2003
Posts: 4,848
Memphis
|
I think your over thinking things. Yes the better coil should fire the larger gap fine and the larger gap may reduce misfires. Try it and see.
Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: HemiRick]
#1454937
06/18/13 07:45 PM
06/18/13 07:45 PM
|
Joined: Apr 2010
Posts: 4,154
bethlehem pa
mikemee1331
master
|
master
Joined: Apr 2010
Posts: 4,154
bethlehem pa
|
Quote:
I think your over thinking things. Yes the better coil should fire the larger gap fine and the larger gap may reduce misfires. Try it and see.
 way over-thinking it. a 40 gap should work just fine for you with the Blaster.
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: dogdays]
#1454939
06/18/13 08:31 PM
06/18/13 08:31 PM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
Go ahead & experiment & try 30 & 40 & even more. An Echlin MO3000 rotor at your NAPA store will have a .060" longer blade for further trials. It's $8 & change out the door. Might even file your current rotor to do the opposite & increase the distance as reportedly it creates a greater booster gap & works better. Holler how it goes
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: dogdays]
#1454940
06/18/13 08:35 PM
06/18/13 08:35 PM
|
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
|
Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
|
Quote:
My 1993 Chevy suburban was running fine but I decided to change plugs, wires and cap just for fun. This was a stock system. To my surprise, the plug gap as found averaged OVER 0.060"! The center electrode was perfectly round. I installed the new stuff, plugs gapped at whatever factory spec, expecting to get better SOMETHING. Net result was zero MPG increase, no other discernable differences, either.
Your system should fire those plugs at 0.045" no problem. If you had all day at a deserted racetrack you could run several runs with plug gap opened each time to find out optimum. Probably won't happen, though.
R.
I have 4 chevy pickups, I'm pretty sure .060" is the correct gap. Also must use platinum plugs.
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: Challenger 1]
#1454941
06/18/13 08:48 PM
06/18/13 08:48 PM
|
Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick
master
|
master
Joined: Mar 2003
Posts: 4,848
Memphis
|
Comparing GM's HEI ignition with our older setups is not a valid comparison.
Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: HemiRick]
#1454943
06/18/13 08:55 PM
06/18/13 08:55 PM
|
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
|
Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
|
Quote:
Comparing GM's HEI ignition with our older setups is not a valid comparison.
I was not comparing, only pointing out that .060" plug gap was probably correct for his 93 chevy. And the "perfectly round" electrode was platinum. Hope he didn't put regular plugs in it?
To the OP, try it and get back to us. What you hear from us don't mean swat.
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: a12superbee]
#1454947
06/19/13 10:12 AM
06/19/13 10:12 AM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
Yes as every different ballast/coil combo has an ideal gap that you find unless you play with it
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: RapidRobert]
#1454948
06/19/13 10:54 AM
06/19/13 10:54 AM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
If you take a mower in that will not start the first thing they do is tighten up the gap and it will usually start right up. Gap is decided by the type and strength of the ignition you have. Over the years I have never seen any gain from larger gap, ever. No gain you can see on dyno or at the track. Get the gap too big and you can see a decrease in performance AKA worn out plugs. An MSD does not care, it will run with the plug wire hooked to anything. Just another area where there is no real world gain but plenty of ideas, discussion, worry, etc .035 will run on anything, .040 will too, many real racers know that you take them out of the box, look for a gap, screw them in and forget about it. FWIW I use about .016 on my Vertex magneto so it will fire at the plug and not upstream somewhere, that thing will re-arrange your hair-do it is so strong. 
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: ]
#1454949
06/19/13 12:26 PM
06/19/13 12:26 PM
|
Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
I love the discussion so far on this. I figured there would be a lot of opinions on this. I am NOT drag racing this car and looking for 'increased performance' per se but maybe slightly nicer street manners in the form of smoother idle, smoother throttle response, etc from the hotter spark. I am not under any illusion that I am going to pick up any measureable horsepower or speed from simply gapping plugs.  I just wondered if I am leaving any benefits on the table by staying at the factory gap of 35 or if by gapping out, I am asking for other problems. Keep in mind this is a street car, first and foremost! For example would having a larger gap and therfore a hotter spark help with pinging/starting/etc? BTW, car has a 727 with a 3.55 SG behind it 28" tires 2400 stall.
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: RSNOMO]
#1454951
06/19/13 01:27 PM
06/19/13 01:27 PM
|
Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,376
|
"I was not comparing, only pointing out that .060" plug gap was probably correct for his 93 chevy. And the "perfectly round" electrode was platinum. Hope he didn't put regular plugs in it?" Challenger1, you are shooting from the hip and you are wrong. Spark plug gap for the 1993 5.7 is 0.035". The plugs were NOT platinum, I took them out myself. They were a standard AC conventional plug. NOT fine wire. The center electrode, which any fool will tell you is supposed to be sharp, was so worn it was hemispherical. The largest gap I measured was 0.072". Put your hat back on your head and stop talking through it. My point was even with worn-out plugs with a way-larger-than-recommended gap, there was no deterioration in performance (which wasn't that great to begin with, but that's another story). Back in the first days (1975) of GM's HEI systems, factory stock gaps ran as high as 0.055". It wasn't too many years before they started bringing the plug gaps back to smaller numbers. R. 
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: cjskotni]
#1454952
06/20/13 02:38 PM
06/20/13 02:38 PM
|
Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
master
|
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
|
Quote:
I love the discussion so far on this. I figured there would be a lot of opinions on this.
I am NOT drag racing this car and looking for 'increased performance' per se but maybe slightly nicer street manners in the form of smoother idle, smoother throttle response, etc from the hotter spark. I am not under any illusion that I am going to pick up any measureable horsepower or speed from simply gapping plugs.
I just wondered if I am leaving any benefits on the table by staying at the factory gap of 35 or if by gapping out, I am asking for other problems. Keep in mind this is a street car, first and foremost!
For example would having a larger gap and therfore a hotter spark help with pinging/starting/etc?
BTW, car has a 727 with a 3.55 SG behind it 28" tires 2400 stall.
the spark wont be any "hotter" with the larger gap it will be just that about .005 longer and very slightly longer in duration.
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: ademon]
#1454953
06/20/13 02:54 PM
06/20/13 02:54 PM
|
Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
Rapid340
top fuel
|
top fuel
Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
|
One dissadvantage of CD(capacitive discharge) iginitions is that they produce low spark duration (but high voltage). To reduce the effects of short spark duration manufactures would recommend opening plug gaps to increase the size of the initial flame kernel. (There are many E-core ignition coils available that have increased spark current duration capability). The MP system (orange, chrome box) is an inductive system (which inherently has long duration sparks) so I wouldnt expect much benefit from wide gaps but all the negatives (stress secondary path, higher percentage of missfires).
Last edited by Rapid340; 06/20/13 04:31 PM.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
|
|
|
Re: Ignition Guru's - Spark Plug Gap to .040" or not?
[Re: ademon]
#1454954
06/20/13 02:58 PM
06/20/13 02:58 PM
|
Joined: Feb 2003
Posts: 10,209
Someplace you aren't
SomeCarGuy
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 10,209
Someplace you aren't
|
I've run big gaps on my plugs and as long as there are no misfires, it has been fine. Can't really say I can tell any huge difference. A feel good thing?
If I have the few extra minutes it takes, I index my plugs so the open gap is pointing up in the chamber. Seems to make throttle response a little better. Maybe wishful thinking for spending the time, but never a bad result.
I want my fair share
|
|
|
|
|
Honestly I don't think you will gain anything, if you don't have a problem NOW. I've been wrong before and I'll be there again, so have fun. 
