Spark Plug Timing

[dolt]

I guess will have to agree to disagree Don. A lot smarter people than me have tested indexing and it's affect on power using a dyno to measure the change.

I was referring to your post that indexing won't show on a dyno, that's simply not true.

Then we agree to disagree. However, I do agree that I made a very general statement and I should have qualified it by limiting it to the HD motor and my own testing. Every motor we tested had been modified and perhaps the dyno would have shown something on a Stage I or stock motor; don't know but seriously doubt it. I find there are many other little things that are often overlooked that, if addressed, will actually register on a dyno and/or reduce 1/4 mile times. Spark plug timing may be on that list but at the bottom. JMHO.:s

 

[Jeff Klarich]

So noted, but Don would you agree in a perfect world that a spark cleanly igniting all available gas in a combustion chamber would produce more power? Does more power equate to more HP? I've built enough race car engines over the years and believe the answer is yes.

I agree in a 2 cylinder engine, indexing will show little movement on a dyno run but I think it will register over a non indexed engine. it's just a matter of physics. JMHO.

 

[Jack Klarich]

This is what an indexed spark plug would look like inside the combustion chamber

 

[dolt]

Guys, not looking for an argument.:cry I believe in what I can prove to myself and I have unfettered access to a dyno to test theories like spark plug indexing and the results of me, personally, not what some guy that knows a guy that has a cousin that married the CEO of Autolite, but me, putting bikes on a dyno, recording data, pulling them off the dyno (not letting them cool down) changing a jet, raising/lower a needle, replacing an NGK plug with an HD Irridium or replacing a non-indexed plug with one that has been indexed, etc. I have seen no measurable change on the dyno between a non-indexed and an indexed plug.

Certainly agree in the theory but put my trust in data.:s I rely on the proper setting of squish and/or singh grooves than spark plug indexing for complete combustion on a modified HD twin.

Not saying plug indexing is bad, not advising against it but just stating what I have seen.

BTW Jack, the HD head is a bathtub head; not shape as the one in the illustration. Bathtub heads and flat top pistons present a very different picture at TDC.:s

 

[Jeff Klarich]

I guess we kinda hijacked this thread to discuss indexing and dyno runs. It's good to be able to agree to disagree, everyone is entitled to their opinion. What works for 1 does not always work for others, not to mention not all dyno tuners are created equal.

 

[Jack Klarich]

Guys, not looking for an argument.:cry I believe in what I can prove to myself and I have unfettered access to a dyno to test theories like spark plug indexing and the results of me, personally, not what some guy that knows a guy that has a cousin that married the CEO of Autolite, but me, putting bikes on a dyno, recording data, pulling them off the dyno (not letting them cool down) changing a jet, raising/lower a needle, replacing an NGK plug with an HD Irridium or replacing a non-indexed plug with one that has been indexed, etc. I have seen no measurable change on the dyno between a non-indexed and an indexed plug.

Certainly agree in the theory but put my trust in data.:s I rely on the proper setting of squish and/or singh grooves than spark plug indexing for complete combustion on a modified HD twin.

Not saying plug indexing is bad, not advising against it but just stating what I have seen.

BTW Jack, the HD head is a bathtub head; not shape as the one in the illustration. Bathtub heads and flat top pistons present a very different picture at TDC.:s

Duly noted:s Troubleheads and Pans would benefit more due to design and high piston dome

 

[dolt]

Thanks guys, healthy discussion.

 

[Jeff Klarich]

Thanks guys, healthy discussion.

Agreed.

 

[Jack Klarich]

Thanks guys, healthy discussion.

Agreed.

Maybe we should be politicians hAAAAA:s
Always good to get as much info out there and let the members decide what they like or add to the discussion IMO

 

[HDDon]

I've been following this thread and one thing it shows is just how good this forum is. I can't think of another site where this wouldn't end up in some type of fight and hurt feelings. Thanks to everyone for making this the type of forum where everyone can feel welcome. I would like to offer my two cents to the discussion. I raced motocross and hydroplanes when I was younger and we searched for any type of advantage we could get. Indexing plugs was one of the things everyone did just to make sure you were doing everything you could to stay in front. I don't doubt that it doesn't show up on the dyno even though it might be a seat of the pants thing. I think Dolt is giving us the straight stuff but like he said it won't hurt.