Indexing plugs

Old 08-16-2009, 06:40 PM
  #1  
chrisr
Senior Member
MASTER BUILDER
Thread Starter
 
Join Date: Jul 2004
Location: Elm Mott, Texas
Posts: 197
Default Indexing plugs

OK, I have several of my fellow racers that index their plugs. It is about half and half on which way they do it. When you index a plug, do you put the spark plug gap pointing down to the piston or up toward the valve springs. I thought I was doing it right but now I am second guessing myself after finding about a 50 50 split among other people.
chrisr is offline  
Old 08-16-2009, 06:45 PM
  #2  
Tod74
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Posts: 4,137
Default

I thought you pointed it toward the exhaust valve. :? to direct the flame or something like that...I don't fool with it so long as it don't hit the piston.
Tod74 is offline  
Old 08-16-2009, 10:41 PM
  #3  
OneBadGMC
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: Belleville, IL
Posts: 658
Default

All of mine are indexed with the gap pointing towards the intake valve.
OneBadGMC is offline  
Old 08-17-2009, 04:10 AM
  #4  
blowninjected540
Senior Member
EXPERT BUILDER
 
Join Date: Mar 2007
Location: Michigan
Posts: 379
Default

I thought the reason for indexing the plugs was to make sure the gap is facing down so if the piston hits the plug it don't close the gap. (right)
blowninjected540 is offline  
Old 08-17-2009, 05:20 AM
  #5  
hammertime
Senior Member
RACING JUNKIE
 
Join Date: May 2003
Location: Coldwater, MI
Posts: 2,998
Default

Originally Posted by blowninjected540
I thought the reason for indexing the plugs was to make sure the gap is facing down so if the piston hits the plug it don't close the gap. (right)

This is always what I've done and the engine builders (nyes,apd) have done also. Between 10-2
hammertime is offline  
Old 08-17-2009, 07:59 AM
  #6  
OneBadGMC
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: Belleville, IL
Posts: 658
Default

Originally Posted by blowninjected540
I thought the reason for indexing the plugs was to make sure the gap is facing down so if the piston hits the plug it don't close the gap. (right)
If the piston hits the plug on a blower motor, you've got bigger issues at hand than worrying about closing up the plug. :shock:

I do it that way only to ensure consistency between cylinders. Honestly, with 23+:1 compression while in boost, I dont think it matters much.
OneBadGMC is offline  
Old 08-17-2009, 09:17 AM
  #7  
FullTimeRacing
Senior Member
DYNO OPERATOR
 
Join Date: Mar 2008
Location: New Orleans,La
Posts: 515
Default

has anyone tested this on a dyno?

I just stick'em in .
FullTimeRacing is offline  
Old 08-17-2009, 09:57 AM
  #8  
OneBadGMC
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Location: Belleville, IL
Posts: 658
Default

Originally Posted by montecarlo84
has anyone tested this on a dyno?

I just stick'em in .
http://www.eatonbalancing.com/blog/2...plug-indexing/

Granted, they're talking about Ford engines, but it's still a decent article.

If you use a plug with a crush washer, you can mark the ground strap or gap side of the plug (depending on which you want to see), and then tighten it, crushing the washer until the mark lines up where you want it.

If you have a taper seat plug, using tapered seat indexing washers will be required.

http://www.summitracing.com/parts/MO...0/?image=large
OneBadGMC is offline  
Old 08-17-2009, 11:15 AM
  #9  
ashbros
Senior Member
RACING JUNKIE
 
Join Date: Nov 2004
Location: St. Louis, Missouri
Posts: 661
Default

What is the correct method?

The old timer that taught me always had me index the plugs and point the gap toward the intake valve. I have done that on N/A & Blower motors.

Is this incorrect amoung the world of engine builders out there?

I am having a hard time swollowing the part about just in cast the piston hits the plug. :?

I by no means am a rocket scientist, but if I have always used clay to check my valve to piston clearance and that also gives me a guide to the distance between the spark plug and piston. Even though math calculations seem to be correct, I have always check my clearances this way. "Just my little bit of self assurance"....

By the way that was an interesting read OneBad.
ashbros is offline  
Old 08-17-2009, 12:28 PM
  #10  
RonOwensRacing
Senior Member
DYNO OPERATOR
 
Join Date: Oct 2004
Location: florence ky
Posts: 498
Default

I have to index my plugs because they will hit and index all of them between 10 and 2 o'clock .
I mark the plug with a sharpie straight down the plug from the strap so i can see where it is and add or subtract washers until they all line up.
RonOwensRacing is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -