spark plug gap -
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back > General Technical Discussions > Engines & Drivetrain > spark plug gap Sale EventSummer is Over! Time for a saleIntroducing MONSTALINER™ UV Permanent DIY Roll On Bed Line

Unread 07-12-2002, 09:59 PM   #1
Registered User
Join Date: May 2002
Posts: 121
spark plug gap

I did a search to try to find what the gap of a spark plug in a 99 4.0 litre, had no luck maybe one of you could help.

desert sand 99 tj sport, 5spd, 4.56, arb front, f8.8 rear, custom bumpers, 1"bl+mml, warn m8000, 35 12.5 trxus
badams is offline   Reply With Quote Quick reply to this message
Unread 07-13-2002, 12:06 AM   #2
Registered User
Join Date: Mar 2002
Location: duhville
Posts: 1,098
sorry to intrude but i have a question about spark plug gaps too.. Is it true that you can gain some power by widening the gap on the plugs? I heard it somewhere on some post but i wanna know if its true.
[b]There comes a time... In every mans life, when decisions... have... to be made. Whether to toil, to labor, or just plain piss your days away.[/b]

[b][COLOR=green]Green[/color] Jeep Club Member #15[/b]
[b]My Jeep Made Me Broke Club Member #2[/b]

93 YJ I-6 w/ stuff

Keep the [COLOR=blue]greasy[/color] side down
Quan is offline   Reply With Quote Quick reply to this message
Unread 07-13-2002, 12:51 AM   #3
Mark K
Registered User
Join Date: May 2002
Location: Central Arizona
Posts: 268
Did you try looking under the hood for the factory sticker? If it's still there and still readable it'll give ya the gap...
Mark K
Don't ask [b] [u]me! [/b] [/u] I just post what my dog [Emma] tells me to.

Member of: [URL=]Arizona Virtual Jeep Club[/URL]
Mark K is offline   Reply With Quote Quick reply to this message
Unread 07-13-2002, 06:59 AM   #4
Registered User
Join Date: Jun 2002
Location: St. Louis, MO
Posts: 41
I know when I got my plugs from Napa, it actually had the gap printed on the recipt. I'm sure it is the same for most years, but my '97 FSM says a gap of 0.035" (0.89mm) for both the 4.0 and the 2.5l.
97 TJ Sport, Red, Too many mods to list, If you want to know just ask.
bonz44 is offline   Reply With Quote Quick reply to this message
Unread 07-18-2002, 08:11 AM   #5
Sold my soul to JeepForum
FunkSkunk's Avatar
1992 YJ Wrangler 
Join Date: Mar 2002
Location: Marble, NC
Posts: 1,814
If you get the new BOSCH plugs you won't have to worry about the gap. Just get the double or the 4 prong ones and slap them baby's in. I got the doubles right now, feels no real noticeable difference. BUt you can't feel much of any performance gain with 33s and 3.07 gears!!
Don't Click Me!
FunkSkunk is offline   Reply With Quote Quick reply to this message
Unread 07-20-2002, 07:59 AM   #6
Registered User
Join Date: Jan 2002
Location: vermont
Posts: 145
the gap is probably .035 for stock
you can open the gap up some, but may foul up and miss fire more often.
I put in a jacbs omni box, and that opens the gap up to .050, but put it a little closer to .045. and I have to change the plugs more often.
98 TJ and 02 Liberty
rogncrys is offline   Reply With Quote Quick reply to this message

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools

Suggested Threads

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. is not in any way associated with Jeep or the Chrysler Corp.