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Title: anyone tried spark plug indexing? Post by: alex d on April 01, 2008, 14:59:48 pm yes, no? where would be better to face the gap?
Title: Re: anyone tried spark plug indexing? Post by: Jon on April 02, 2008, 06:13:30 am 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.
Title: Re: anyone tried spark plug indexing? Post by: alex d on April 02, 2008, 11:33:00 am 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
Title: Re: anyone tried spark plug indexing? Post by: Dominick Luppino on April 02, 2008, 19:10:39 pm I tried it, no HP gain. It was a lot of work for nothing…
Title: Re: anyone tried spark plug indexing? Post by: Scott Novak on April 03, 2008, 10:01:56 am 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 |