Welcome to the all new Geo Metro Forum. We hope you enjoy your visit.You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are features you can't use and images you can't see. Registration is simple, fast, and completely free. If you're already a member please log in to your account to access all of our features: Join our community! |
| Indexing spark plugs; Indexing spark plugs | |
|---|---|
| Tweet Topic Started: Jul 26 2014, 11:27 PM (1,023 Views) | |
| Mrbreeze | Jul 26 2014, 11:27 PM Post #1 |
![]()
|
I searched and did not find anything regarding this, I have always done this and wondered if anyone else does, I also use a one step hotter plug, calls for a BPR6ES and I always use BPR5EY-11, no problems, just thought I'd throw that out there for some feedback.. |
![]() |
|
| perfesser | Jul 26 2014, 11:39 PM Post #2 |
|
Elite Member - Former Metro owner
![]()
|
What is "indexing"? |
![]() |
|
| Mrbreeze | Jul 26 2014, 11:45 PM Post #3 |
![]()
|
I mark the ceramic with a sharpie where the ground tip points and I use old plug washers to shim the plug so that it points down to the piston, into the combustion chamber, if necessary.. That way the spark is always firing toward the piston.. |
![]() |
|
| Old Man | Jul 27 2014, 01:02 AM Post #4 |
![]()
|
What 'gains' have you documented by using 'indexing'? |
![]() |
|
| Mrbreeze | Jul 27 2014, 01:35 AM Post #5 |
![]()
|
Well I've never burned any valves... I do know that if I use stock heat range plugs it just runs like I put regular fuel in it, not very zippy.. |
![]() |
|
| Bad Bent | Jul 27 2014, 02:42 AM Post #6 |
|
Facetious Educated Donkey
![]()
|
A little research, at http://www.sr20-forum.com/naturally-aspirated-all-motor/4369-how-index-your-spark-plugs.html there is this pic: Spark plug firing "bubble"At http://www.hubgarage.com/mygarage/summitracing/blogs/10030 and http://www.hubgarage.com/mygarage/summitracing/blogs/10030 they index the flame toward the valves. From Hubgarage.com "The technique of indexing a spark plug involves getting the ground strap of the plug properly positioned when the plug is fully seated in the cylinder head. The ideal situation is to have the spark gap facing directly at the intake valve and approaching fuel charge. This increases combustion efficiency and puts the spark directly in the fuel charge path. When left to chance, if the ground strap would end up between the intake charge and the spark gap it blocks the flow, causing unneeded turbulence, and results in a less efficient ignition of the charge. In very high performance racing engines, indexing can also provide additional clearance for high dome pistons." A little pricey but here are Moroso indexing washers for spark plugs: http://www.ebay.com/search/Moroso+spark+plug+washers But the Mrbreeze indexing may save G10 valves A little more searching and NGK says this: "This is for racers only !! Indexing refers to a process whereby auxiliary washers of varying thickness are placed under the spark plug's shoulder so that when the spark plug is tightened, the gap will point in the desired direction. However, without running an engine on a dyno, it is impossible to gauge which type of indexing works best in your engine. While most engines like the spark plug's gap open to the intake valve, there are still other combinations that make more power with the gap pointed toward the exhaust valve. In any case, engines with indexed spark plugs will typically make only a few more horsepower, typically less than 1% of total engine output. For a 500hp engine, you'd be lucky to get 5hp. While there are exceptions, the bottom line is that without a dyno, gauging success will be difficult." Or a 50hp engine would "be lucky" to get 1hp.
|
![]() |
|
| Woodie | Jul 27 2014, 04:47 AM Post #7 |
![]()
|
Optimistic math. A 50 hp engine would be lucky to get .5 hp. |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Electrical Systems · Next Topic » |


Welcome to the all new Geo Metro Forum. We hope you enjoy your visit.






Spark plug firing "bubble"
7:27 PM Jul 10