Indexing plugs

Turnip · Post by **Turnip** » Tue Feb 24, 15 10:02 am

Hi all,

What are your thoughts on indexing spark plugs. Some say it should be with the strap facing the inlet and others facing away.

Dave-R · Post by **Dave-R** » Tue Feb 24, 15 10:37 am

After trying it both ways my thoughts are it makes sod all difference in a Mopar wedge head.

Blue · Post by **Blue** » Tue Feb 24, 15 11:30 am

My thoughts too, the plug is in such a lousy position anyway I wouldn't have thought indexing would make a blind bit of difference.

Dave999 · Post by **Dave999** » Tue Feb 24, 15 4:34 pm

face the gap towards the exhaust valve...
thats the hotest area

so it will go off better

and that comment is based on absolutely nothing to do with cars or experience or anythig really other than GCSE chemistry

hot stuff does faster chemical reactions than cold stuff so will cause a more dramatic expansion!!!!!

think its probably just an idea someone had because he had a lot of very narrow thin washers to sell.
The spark will go off the electrode at a different place every time as the sharpest point (the place where a spark tends to go from) it went from last time was erroded away by the spark produced from it.

side gapped plugs is another thing that Might MIGHT work, but again subjected to sharpest closest point between centre and strap

and then there are the plugs with the kinda ball bearing centre electrodes...

Dave

shovelheadrob · Post by **shovelheadrob** » Tue Feb 24, 15 6:45 pm

Only ever had to bother with indexing on one engine, when we used to race in Super Modified the motor we used was a bit tight on clearance & if the plugs weren't indexed the pistons would close them up a bit! Other than that I think it's not necessary.

Mossy68 · Post by **Mossy68** » Tue Feb 24, 15 7:41 pm

shovelheadrob wrote:Only ever had to bother with indexing on one engine, when we used to race in Super Modified the motor we used was a bit tight on clearance & if the plugs weren't indexed the pistons would close them up a bit! Other than that I think it's not necessary.

Now that's working to tolerances !

Turnip · Post by **Turnip** » Tue Feb 24, 15 8:25 pm

We had a few visits from Michael ( the owner of the Samantha Pro Stock team) and his crew trying to help us with some problems we were having.

They told us to cut the strap back to a point and then face the open side to the inlet

Dave-R · Post by **Dave-R** » Wed Feb 25, 15 9:25 am

An old race trick used to be to grind the centre electrode to a point. The plug will not last long like that of course.

Sparks jump easier, faster (and at a lower voltage) from a sharp point.

But I don't see that adding power or fixing any issues with the way the engine runs. It might be a crutch for an ignition system not working correctly though.

Dave999 · Post by **Dave999** » Wed Feb 25, 15 11:28 am

Turnip · Post by **Turnip** » Wed Feb 25, 15 1:25 pm

We were have a misfire issue at the time but cured that by putting the MSD in the bin

Guy · Post by **Guy** » Wed Feb 25, 15 3:40 pm

Turnip wrote:We were have a misfire issue at the time but cured that by putting the MSD on the bin

I didn't know you called your car that

but I have heard you call it by some other names

Les Szabo · Post by **Les Szabo** » Wed Feb 25, 15 3:52 pm

Turnip wrote:We were have a misfire issue at the time but cured that by putting the MSD in the bin

Suprised you don't use the FBO ignition, certain people say they outperform MSD...

Les

Les Szabo · Post by **Les Szabo** » Wed Feb 25, 15 3:52 pm

Turnip wrote:We were have a misfire issue at the time but cured that by putting the MSD in the bin

Suprised you don't use the FBO ignition, certain people say they outperform MSD...

internet

GTXJim · Post by **GTXJim** » Wed Feb 25, 15 4:56 pm

years ago I read that indexing the plugs gave you an extra HP per plug, 8 free HP, they said you aim the electrode towards the exhaust valve, did it on the GTX couldn't tell the difference, don't bother now, I know Dave Wilson indexes his plugs on his Nitro TMD, they are a twin plug BAE Hemi and he has the electrodes facing each other.

Dave-R · Post by **Dave-R** » Wed Feb 25, 15 4:59 pm

GTXJim wrote:years ago I read that indexing the plugs gave you an extra HP per plug, 8 free HP, .

Putting a magnet on your fuel line and fitting an electric fan above the carb both give you more HP than that.