Technical INDEX SPARK PLUGS ( anyone else do it )

Ok, you've lost me....

 

The distributor is a mechanical device that directs the current to fire the plugs it can also be the control to the flame kernel Starting and stopping (along with the coil and other ignition parts). Once the mixture is ignited the length of the burn is controlled by the amount of heat applied (from the plugs etc.) the amount of oxygen available, and the amount of fuel as in any fire. When plugs are indexed the flame kernel that starts the combustion is Larger therefore HOTTER so the mixture is exposed to more more heat sooner and hotter resulting in a larger combustion of the mixture.

With the ignition advanced mechanically yes the mixture STARTS combusting earlier but all things being equal it stops the spark sooner also.

The indexing ONLY provides a bigger hotter flame earlier therefore the mixture burns longer from the introduction of more heat sooner rather that a smaller flame from an unindexed plug which is provided for the same amount of time mechanically.

Perhaps a little analogy is in order to help people understand. You have all seen videos taken holding the video vertically yes they work just fine look the same same length etc. Now if simply by rotating the camera and shooting the exact video with the camera SIDEWAYS the result is a WIDER more filling of the frame video.

Without indexing the fuel is ignited by the tall slim video works just fine BUT with indexing the fuel mixture is ignited by the LARGER WIDER video all other things being equal the bigger larger video is the same as the flame with indexing.

 

I tried it from time to time and in the toolbox were all different size copper shims used for indexing the plugs.
I think it's really hard to say just how much it helped or hurt or maybe did not make any difference.

I can tell you that from doing dyno pulls and changing different brands of spark plugs for each pull it never made much difference at all.
One time a friend had either 3 or 4 brand new manifolds in boxes and he asked me to look at the runners to see if they all looked exactly the same which they did. No machining marks or anything.

When they installed one manifold it made a 32 HP gain on the dyno and that really caught everyone's attention.
It was used for many years going through tech many times.

Jimbo

 

How many time have we done stuff because it's allways been done that way with no proof it helped. I remember a local racer that was successful would do worthless stuff to his car and laff when it showed up on other cars a week or two later.

 

Hmmm. . . I've always worked under the assumption that you only needed a single, sufficient spark to ignite the air/fuel charge in the cylinder. Once ignited the fuel will burn to completion on its own with no additional "spark" present, assuming also a proper fuel mixture and general engine design.

I'm thinking that the spark duration would be shorter than the time it takes the fuel to burn to completion, though the whole event is "instantaneous" for all intents and purposes.

 

YES you got it. AND the better the spark the more efficient it is.

 

i started the process today.first plug our no5 as luck would have it was 180 degrees out.so moving on to second cylinder im marking the plug twice once with tipex for the open end and once with a sharpie marking the strap end .ill allways be able to see one or the other mark.the tipex may take a few minutes longer to do but what the hell,could make that up on the 8 cylinders.too hot for this game here today im off for another spin.

 

finally finished the indexing today i used a moroso kit from summit.some plugs took 1 shim others took two.now all plugs electrodes are pointing the centre of the combustion chamber.there is a marked difference in the running ,starting and idle.seems to be running really clean and responsive too.took about 3 hours overall.need to skim the plug socket on a lathe to stop it fouling the headers .that would speed things up.very happy with the results and glad i took the time to optimise the plugs.ill just add that i was starting from a bad place with a combination of denso plugs and edelbrock heads with 7 of the 8 plugs pointing away from the centre of the combustion chamber others may not get the benefit i did.