anyone tried spark plug indexing?

[alex d]

yes, no? where would be better to face the gap?

[Jon]

I have learnt to point it halfway over to the exhaust valve, but I don't know if it does anything for a normal VW combustion camber.

[alex d]

oh well, I'll give it a try, in fact I have to find some really thick washers as the plugs protrude too much into the chamber

[Dominick Luppino]

I tried it, no HP gain. It was a lot of work for nothing…

[Scott Novak]

I index my spark plugs.  I can't afford dynamometer time so I don't really know if it is making much difference.  But at the very least, I think it should help the cylinders run more uniformly.

Initially I pointed the outer electrode midway between the intake and exhaust valve.  However, I noticed that the coloring around the spark plug insulator wasn't uniform on either side of the outer electrode.  So now I point the electrode a little more towards the intake valve, and the spark plug coloring is uniform on either side of the outer electrode.

The other reason that I index my spark plugs is to make sure that the threads don't project into the combustion chamber where they could heat up and cause pre-ignition.

For better or worse I'm running a semi-hemi combustion chamber with a very low 6.8:1 compression ratio.

My spark plug gaps are set at 0.065" (1.65 mm) and I use a Jacobs Pro Street ignition and Jacobs Ultra Torquer Coil.  I'm using a Mallory vacuum advance Magnetic Breakerless Ignition (MBI) distributor with the larger 208M 8-cylinder distributor cap modified for 4-cylinder use.

Scott Novak