Engine Mechanical Topics Discussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.

Spark Plug Indexing

Thread Tools
 
Search this Thread
 
Old Oct 3, 2005 | 04:48 PM
  #1  
HDF Tech's Avatar
HDF Tech
Thread Starter
|
Banned
Joined: May 2005
Posts: 14,496
Likes: 156
From:
Default Spark Plug Indexing

Spark Plug Indexing

One of the simplest ways to improve the combustion in your engine is to index the spark plugs. Indexing the plugs ensures that the gap is facing the combustion chamber. If the stem of the ground electrode is facing into the chamber, then the spark is shrouded from the majority of the fuel/air mixture. When the stem of the ground electrode is facing away from the chamber, the fuel/air mixture will burn more quickly and completely (#2, #3).

The easiest way to accomplish this is to mark the insulator or metal base with a felt tip marker showing the location of the ground electrode stem. Install the plugs and torque to 10 ft-lbs. Ideally, the gap will be facing toward the intake valve or centered between the intake and exhaust valves (#2, #3). You want to be able to see your mark on the plug (#1). It's best to have the line fall between the two head bolts. If they are not within this range, try swapping the plugs from the front head to the rear head and vise versa, and they will usually come pretty close. While some people may notice a difference in their engine’s performance, most will not. As a general rule, it is recommend replacing the spark plugs with new standard plugs every 5,000 miles.


[IMG]local://upfiles/2318/EED0EF8FB923441C8DB8FB64E5A21845.jpg[/IMG]

[IMG]local://upfiles/2318/37909E78356B4B58A6C605AB16C78121.gif[/IMG]

[IMG]local://upfiles/2318/19B9498E82DD4486958F8416648EF1F0.gif[/IMG]

 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Chuck U. Farley
2014-2024 Touring Models
15
Mar 15, 2015 02:23 PM
gascap13
Touring Models
15
May 17, 2009 07:46 PM
grunt25inf
Touring Models
9
Sep 18, 2007 02:06 PM
LOU
Touring Models
8
Apr 26, 2007 10:31 PM
HDF Tech
Engine Mechanical Topics
0
Jul 2, 2005 03:48 PM




All times are GMT -5. The time now is 07:51 PM.

story-0
10 Most Awkward-Looking Motorcycles Ever Built

Slideshow: Not every motorcycle can be a design icon, and these machines prove that bold styling doesn't always age gracefully.

By Verdad Gallardo | 2026-06-18 10:29:31


VIEW MORE
story-1
Jason Momoa Is Turning Classic Harleys Into PHEVs

Slideshow: Jason Momoa's latest restoration project blends 1920s Harley-Davidsons with modern electric technology, creating some of the most unusual hybrid motorcycles ever built.

By Verdad Gallardo | 2026-06-10 17:18:58


VIEW MORE
story-2
Harley-Davidson Fat Boy Becomes a Dark, Decepticon-Inspired Custom

Slideshow: Killer Custom's latest build relies on styling changes rather than performance upgrades, giving the cruiser an entirely different personality.

By Verdad Gallardo | 2026-06-03 18:28:05


VIEW MORE
story-3
6 Weirdest Harley-Davidsons Ever Sold to the Public

Slideshow: From military-inspired singles to scooters and three-wheel utility vehicles, these Harleys took the company far outside its comfort zone.

By Verdad Gallardo | 2026-06-02 18:34:10


VIEW MORE
story-4
7 Times Harley-Davidson Chucked Tradition Out the Window

Slideshow: Harley-Davidson built its reputation on nostalgia, but every so often, the company took a hard left turn into the future.

By Verdad Gallardo | 2026-05-20 11:18:19


VIEW MORE
story-5
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-6
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-7
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-8
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-9
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE