Anyone tried this?? I just read a great article about indexing and they were able to get about 6-8hp out of a 150hp Porsche 944 motor... The article found that the best results were had by having the opening facing the exhaust valve... just curious if anyone has tried this (and possibly in conjunction with opening the gap).

 

I used to do that in my SB Ford engine but, that was only because the spark plug was not centered in the head so the side electrode could shield the spark from the compressed combustion mixture. Since our plugs, I am 99% certain, are in the center of the head, I doubt there would be much benefit.

 

Does anyone have a picture from the service manual that shows the heads and spark plug location??

 

jeffa55,

If the indexing article is online, could you please post a link?

Thanks,
Jeff

 

It isn't online (that I know of)... It was in a Porsche Excellence magazine. It was a well written article and basically found the following (based on tests and a dyno):
- Split fires are a TOTAL waste of time
- Having the plug opening pointed towards the exhaust valve produced the best results (at least on that motor)
- Having the plugs all gapped the same and facing the same direction (wherever that may be) is VERY important. Basically, it said that AT LEAST have the plugs be consistent in the engine and you will see some gains.

 

Yes, it's centered. Here's an illustration from the service manual.

 

Here's another.

 

Here's another.

 

Do you know which of the valves is the intake and which are the exhaust?? I am going to try, at least, having them all point the same, but would love them to point toward the exhaust side.

 

I wonder how much variation +/- in torque values is acceptable for spark plugs?

I figure you'd generally like higher torque rather than less torque than the recommended specs, within reason.

Maybe you'll luck out and only need to turn an extra 20 degrees or so. I'd be afraid of stripping the threads though.

Can spark plugs be ordered with different angles of the electrode vs. the thread start?
--
Jeff

 

Actually, you index plugs by using shimming washers... they sell them specifically for indexing. You do not index by over or under tightening. Basically, the best way to do it is to make a mark on the ceramic part that lines up with the electrode, then you use shims and tighten down the plug so that mark (the electrode) is then pointed in the right direction.

 

Anyone know which vavles in the pic are the exhaust and which are intake??

 

In the picture above (RH bank) the exhaust ports are on the top.

When indexing your plugs, just remember that the intake ports are toward the center of the car, and the exhaust ports are toward the wheel wells.