Spark plug tricks?

You can also index the plugs. That's where you make sure the gap of the plug is pointed towards the center of the combustion chamber on all cylinders.

These spark plug tricks do work but we're talking about the type of things you do when you're looking for that last 1 or 2 horsepower. On a street car it's kinda pointless.

hmm, this is particularly interesting to me 85! good find! i'll have to go out and give this a try tomorrow! the only question is, did you leave the ENTIRE electrode exposed? if so, how the hell did you gap it afterward? also, what did you end up gapping them at?

IMO...

I would place more emphasis on determining the correct plug and gap than attempting to index your plugs. The rate of return for a properly indexed set of plugs is likely to be in the range of 1 - 2% which is essentially worthless unless you're a competition racer and need the extra .01 seconds. I have seen more harm done using improperly gapped plugs than because they are facing random directions.

But let's assume that you deem it worth your time. Each engine, or more accurately each cylinder, reacts differently from indexing and requires a different position. Based on final runner direction and swirl, the incoming air passes through the intake valve in a calculable speed and direction which is then theoretically turned and aimed towards the exhaust valve as the piston travels towards TDC. So, depending on the direction of rotation and center of compression (contrary to popular opinion, there are varying levels of compression within the combustion chamber), the plug face needs to be oriented towards the oncoming slug of air in order to facilitate a more complete and thorough ignition. Based on the factors just discussed, this may mean the plug needs to be oriented toward the intake valve, towards the exhaust valve, or some angle in between. The only way to correctly determine this is through airflow models and dyno tuning.

Of course, if you have a mild case of COD (Obsessive Compulsive Disorder) as do I, you'll index the plugs simply because you can't stand the thought of them facing in completely random directions. But honestly, I think you'll get a better drop in quarter time if you take a large dump before you race.

taking a dump for teh win.


dont forget to tighten the belt an extra notch afterwards.

This is all interesting, and seems to have some theory behind it, but I've bought the best of the best plugs and had the cheapest of plugs and I can't say I've ever noticed much of a difference. I personally think its a placebo effect on a NA street car. Are you sure the reason your car is running so well isn't from the cooler fall air?

Not to be completely pessimistic, but I'd just like to see some dyno numbers before I go hacking at my electrodes or buying special washers and indexing plugs.