many of you might have known of this, but i had never heard of such a thing. anyways, i'm always lookin for ways to mess with the car in the winter. when money is tight, i turn to small, and practically free details. anyways, i was talking to an old time racer about the usual BS, and he got to a thing called spark plug "indexing" as he called it. basically, the point of it is to find hp out of a motor. you're trying to get the electrode to point down towards the cylinder so the "arm" of the spark plug is pointing towards the piston. all you have to do is mark the threads on the plug so that u know when the "arm" is pointing down. not all the threads are the same, so it will take you trying each spark plug on every cylinder until the plug tightens about where your mark is. it might even take a couple sets of plugs to accomplish (to find the rigt threads), but has proven for 10hp on a 350hp V8 and a slightly more effecient burn. not anything huge, but an old trick that i don't mind trying on my own car for ****s and giggles. now only if changing lt1 plugs would be a bit easier....

 

I have heard that to I don't think it will make that much of a diff. on a LT1 or any newer computer controled car but it can't hurt. I would only take the time to do it if the headers are off.

 

I would only take the time to do it if the headers are off.[/QUOTE]

Very, very very true. If my plugs go bad, i'm pulling the edelbrock shorties off and ditching them before i put new plugs in. the edelbrocks make it virtually impossible to change the plug on the #2 cylinder. the tube goes right over where the socket needs to go. took me 4 hours, and 2 small flex head extensions stuck together on the #2 cyl. to change plugs

 

I don't know if it is really worth 10hp in a street engine or not I would guess it has a lot to do with chamber shape and piston tops the LT1 does pretty well in those areas. That said if the headers are off or the heads for that matter why not index a few set ahead of time just make the plugs where they need too go later, can't hurt and is just a little of your time.

 

HEll i lucky to get the damn plug it the hole...i could care less as long as i get that bitach threaded!

 

even though the technology has improved, as well as chamber effeciency and the addition of fuel injection, the point of indexing still remains; create the shortest route possible for the spark. prevent the spark from having to go around the "arm" of the spark plug. definately not something you should go spend hours doing, but lie you saif, if you've got the headers off it's worth a chance

 

I spent 3 weeks in school doing nothing but indexing spark plugs and putting bolt-ons's on a 02' TA and a 94 Camaro, and then running them on a dyno. The biggest gain I ever saw off of indexing was 2hp.

Nothing wrong with doing it of course, I might do it for the hell of it, if my engine was pulled. too much work if it was still in the car. Also, keep in mind, you may have to go through 50 plugs before you find 8 that work.

Unless you have a large collection of plugs just lying around. I wouldn't say this is really a free mod.

 

They sell spark plug indexing kits, they are flat copper washers for difference thickness. Instead of trying 50 different plugs, you can mess with the washers. The easiest way to do it is with the head off so you can see the plug electrode. I thought it was supposed to be pointed toward the exhaust valve.

 

Thats correct. and if you can find one of those kits it will be easier. You also don't need the head off. They sell indexing plates, its a plate with a spark plug hole thredded in it.

 

And I'm willing to bet you could see a 2 hp variance just by doing nothing! Interesting topic though.

 

yeah, thats pretty much true.

also, while most cars (Civics) loose HP with a CAI, I saw f-body's make as much as 17hp

 

might as well side gap them while youre at it

 

Do most cars really lose hp with a cai??

 

The washers won't work with tapered seat plugs like we use though.

 

For us, I would say indexing the plugs is not worth the trouble. It's an old trick for getting the most out of a race engine.