spark plug gap 347?

jcw88

Never played w/ it before so i'm still a virgin!

Mar 20, 2007

53

0

0

fernandina, fl

Sep 7, 2007

#1

• Sep 7, 2007

• #1

i just thought of something while i was surfing the forums, what is the right spark plug gap for a 347 stoker, p&p victor jr heads, victor jr intake w/ efi spyder power elbow, accufab 80mm tb, 36lbs injectors, msd distributor, 6al box, 255lph fuel pump jumbo rails, hell to much stuff, anyways can somebody give me an ideal? my local performance shop say .055 but seems alittle high

 

Jozey

New Member

Nov 11, 2003

127

0

0

Tucson,AZ

Sep 7, 2007

#2

• Sep 7, 2007

• #2

stock gap is around.045.i always run mine alitte smaller like .040.

 

jcw88

Never played w/ it before so i'm still a virgin!

Mar 20, 2007

53

0

0

fernandina, fl

Sep 7, 2007

#3

• Sep 7, 2007

• #3

thanx for the advice i have them gapped at .055 now but i think i'll set them back to .045..

 

Roland69

Sergeant Tangnet

Sep 17, 2005

2,867

2

58

Port Elgin, Ontario

Sep 7, 2007

#4

• Sep 7, 2007

• #4

0.52-0.56

 

5spd GT

"the 5.0 owns all"

Founding Member

Aug 7, 2002

9,516

6

99

Arkansas

Sep 8, 2007

#5

• Sep 8, 2007

• #5

Stock gap is .052"-.056"...

It really depends on what compression you are running. Typically the higher compression, the lower the gap needs to be...do you know your compression?

Also, you do have a slightly upgraded igniton over stock with the 6al. That allows a bit larger gap.

Run as much gap as you can without it having a miss at any rpm...

 

87Mustang351

Member

Sep 12, 2005

220

1

16

Canada, Nova scotia, Cape Breton

Sep 8, 2007

#6

• Sep 8, 2007

• #6

whats the best gap for my car? and how do i set it, im gong to the track on the 15th and want my car running top notch!

 

Grn92LX

Fidanza Man!

Founding Member

Jan 14, 2001

6,819

64

129

New York

Sep 8, 2007

#7

• Sep 8, 2007

• #7

Stock gap is .054". I gap my autolites @ .045" with my 11:1 pump gas 347.

 

5spd GT

"the 5.0 owns all"

Founding Member

Aug 7, 2002

9,516

6

99

Arkansas

Sep 8, 2007

#8

• Sep 8, 2007

• #8

Lol.

Stock gap is .052"-.056".

.054" falls between that.

I run .045" on my 9.5:1 pump gas 306...hehe.

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,160

17,854

224

Massachusetts

Sep 8, 2007

#9

• Sep 8, 2007

• #9

jcw88 said:

imy local performance shop say .055 but seems alittle high

Click to expand...

Stock gap on the 87-93's is 0.052-0.056"

SO the gap the shop gave you sounds right for an N/A car.

Typically, plug gaps are dependant on ignition. You want to run as BIG as you possibly can before expeirencing misfiring. The reason is the bigger the gap, the larger the spark and the better chance of igniting all of the air/fuel mixture.

The stock ignition is good to a 0.056" gap, with aftermarket components you can sometimes creep it up a bit, but for the most part 0.054" is what most N/A Mustangs run.

You don't really want to make the gap smaller on an N/A car. It's really only done with boosted cars or nitrous because of the spark blowing out over a larger gap.

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,160

17,854

224

Massachusetts

Sep 8, 2007

#10

• Sep 8, 2007

• #10

Jozey said:

stock gap is around.045.

Click to expand...

On the 87-93's it's 0.054"


There earlier Mustangs used the 0.045" gap, and a lot of references incorrectly list it for all 5.0's


On the emmissions label under my hood, it states the gap range as 0.052"-0.056"

 

bluevenom867

I will have images of molesting stuffed animals in

Dec 15, 2003

1,704

1

0

St.Petersburg,FL

Sep 9, 2007

#11

• Sep 9, 2007

• #11

Witch coil are you runing? If its an MSD Blaster series:

.04

If you plan on spraying,drop down to .035-.032

Btw,spark gap will have no effect on performance so long as its not misfiring to begin with,if you have un-burned fuel (witch also would cause lean spots in other parts of the burn) increased plug gap won't solve that. Poor A/F mixture quality, witch has everything to do with the intake to the piston dome/valve reliefs,is responable for that.

 

87Mustang351

Member

Sep 12, 2005

220

1

16

Canada, Nova scotia, Cape Breton

Sep 9, 2007

#12

• Sep 9, 2007

• #12

im gonna be running my car with motor first and tis a 351, and then im gonna go with nitrious, is there any inbetween i can set my plugs at to get the best performance both ways?

 

bluevenom867

I will have images of molesting stuffed animals in

Dec 15, 2003

1,704

1

0

St.Petersburg,FL

Sep 9, 2007

#13

• Sep 9, 2007

• #13

87Mustang351 said:

im gonna be running my car with motor first and tis a 351, and then im gonna go with nitrious, is there any inbetween i can set my plugs at to get the best performance both ways?

Click to expand...

The gap for nitrous will run fine on motor,but unless your spraying less than 150hp,that won't matter much as plug gap wont be the issue,heat range will.

The motor n/a will probably like a plug thats one heat range hotter,where as on juice you'll need one thats colder.If your runing 150hp or less,no worries though.