69 351 w spark plug gap .032-6 or .042-6 - MustangForums.com


Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

Reply
 
 
 
Thread Tools Search this Thread
Old 04-22-2012, 01:00 PM   #1
dmaclaren
2nd Gear Member
Thread Starter
 
Join Date: Mar 2009
Location: NH
Posts: 380
Default 69 351 w spark plug gap .032-6 or .042-6

I have read both and in pulling all my plugs, they are in the .042 - 6 range.

Are my gaps off from the previous owner or is that right? it's a 1969 351w
dmaclaren is offline   Reply With Quote
Old 04-22-2012, 03:55 PM   #2
BuckeyeDemon
2nd Gear Member
 
Join Date: Feb 2010
Location: Ohio
Posts: 315
Default

the shop set mine at .030" lots of people run .035".

the bigger the gap, the higher the voltage, which i would expect to be harder on wires/caps/rotors.
BuckeyeDemon is offline   Reply With Quote
Old 04-22-2012, 05:41 PM   #3
dmaclaren
2nd Gear Member
Thread Starter
 
Join Date: Mar 2009
Location: NH
Posts: 380
Default

I'm running electronic ignition, I have them gaped at .046, wonder if I should reduce to the .036. I was just reading that for elec. ign., .04x is the way to go.

Now I am not sure
dmaclaren is offline   Reply With Quote
Old 04-22-2012, 05:49 PM   #4
BuckeyeDemon
2nd Gear Member
 
Join Date: Feb 2010
Location: Ohio
Posts: 315
Default

there seems to be a love affair with increasing the gap with a more powerful ignition system. i personally don't understand the rationale. maybe someone here will explain it to me.
BuckeyeDemon is offline   Reply With Quote
Old 04-22-2012, 11:22 PM   #5
The_Dude
1st Gear Member
 
Join Date: Jun 2006
Posts: 83
Default

I run .045 with an electronic ignition and .036 with points. The bigger gap allows for a bigger fatter spark. An electronic ignition has more volts to jump the larger gap.
The_Dude is offline   Reply With Quote
Old 04-22-2012, 11:43 PM   #6
musnicki
3rd Gear Member
 
musnicki's Avatar
 
Join Date: Dec 2007
Location: Bangkok, Thailand
Posts: 959
Default

I have mine at 40, NGK plugs with MSD 6AL box. I don't notice a difference, I was told between 35 and 45, so I set it at 40. A bigger spark makes for a more complete burn I guess?
musnicki is offline   Reply With Quote
Old 04-23-2012, 01:30 AM   #7
Starfury
6th Gear Member
 
Join Date: Aug 2007
Location: Davis, CA
Posts: 5,748
Default

It helps ignite the mix more reliably. GM HEI systems (which use ~100kV coils) are commonly run with a .050-.060" gap.

With a stock coil and electronic ignition, I'd say .035". With an aftermarket 40kV coil, call it .040.-.045".
Starfury is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
what are the odds - Service Engine Soon light lincolnshibuya V6 (1994-2004) Mustangs 9 12-08-2015 05:37 PM
Bad cylinder? Dathan V6 (1994-2004) Mustangs 4 10-05-2015 06:52 AM
04 Mach 460 system, Installed Aftermarket HU, No Highs/Tweeters breaking Audio/Visual Electronics 5 10-02-2015 02:27 PM
Clear codes on '94 sn95 BOB ROME 5.0L (1979-1995) Mustang 2 09-28-2015 12:10 PM
Slight surge at 1500ish rpm lmurf60 4.6L (1996-2004 Modular) Mustang 1 09-24-2015 11:07 PM


Tags
04, 1969, 351, 8mm, cobra, gap, gapping, ignition, msd, mustang, oem, plug, plugs, proper, size, spark, windsor, wires

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -5. The time now is 05:14 AM.