Spark plug gap? - Ranger-Forums - The Ultimate Ford Ranger Resource

4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

LinkBack Thread Tools Search this Thread
Old 03-29-2014
Thread Starter
Join Date: Mar 2010
Location: bernardsville nj
Posts: 1
Spark plug gap?

I have been following the various spark plug discussions and have now Autolite XP5144 plugs on hand. I have seen the specs for the gap as .054 and up to .065. What is the correct gap?
Reply With Quote
Old 03-29-2014
RF Veteran
iTrader: (1)
Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,573
4.0l OHV and 4.0l SOHC use different length spark plugs but the recommended gap is the same, 0.054

Recommended gap is not written in stone, it is determined for overall performance and life.
As an engine gets older it will get lower compression and some cylinder oil intrusion, from valves and/or rings, this is normal, welcome to the physics of friction, lol.

General rule of thumb for spark plug gaps is that you can change the recommended gap by +/- 0.01 to suit your driving habits and engine condition, so 0.054 could be gapped 0.044 to 0.064

The larger the gap the stronger the spark but the shorter the time between regapping or replacement.
Larger gap will give better cold starts and low RPM performance.
Smaller gap will have harder cold starts and better high RPM performance.
There is a heat and recovery time frame at work here, wide gap produces a stronger spark BUT at high RPM, 4,000+, you will see power curve dropping off because coil can't charge fully for larger gap, narrower gap has a "weaker spark" BUT a better spark above 4,000 RPM than wider gap, so power curve stays higher longer.

If you are dealing with higher mile engine that struggles cold then going from 0.054 to 0.059 would be a good test so see if spark is the reason for the struggling.

Last edited by RonD; 03-29-2014 at 03:50 PM.
Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Spark Plug Gap Dangerranger01 4.0L OHV & SOHC V6 Tech 20 03-08-2016 09:37 PM
Spark Plug Gap Yellow_edge_4x4 4.0L OHV & SOHC V6 Tech 6 02-24-2009 01:43 AM
.054 Whats your spark plug gap? ramrezz425 4.0L OHV & SOHC V6 Tech 0 02-06-2009 01:33 AM
spark plug gap, how much does it matter? otterboy_99 4.0L OHV & SOHC V6 Tech 1 11-25-2006 08:24 AM
Importance of correct spark plug gap? IN2 FX4 General Technical & Electrical 3 11-29-2005 11:41 AM

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

All times are GMT -6. The time now is 01:51 AM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.