Autolite double platinums

[Down_South]

OK,

"...how are you going to match the resistance of the gaps between the cylinders..."

Yes, I understand this is an issue, but as long as the pressure difference between each cylinder is within the manufacturer's specified PSI, the ignition system is designed to function properly.

"...how many times you have to match it, and how often you have to do this over the life of the plugs?..."

Only once, and again only once.

 

[pavelow]

I'm running Autolite DPs in the Jetta and can't say anything bad about them.

 

[GMBoy]

Originally Posted By: Vikas
Anybody remember "indexing"?



Yep. They still sell the little kits at Summit to do it. The idea was to get the electrode facing the "kernel" for better combustion.

 

[1kickbuttranger]

Originally Posted By: GMBoy
Originally Posted By: Vikas
Anybody remember "indexing"?



Yep. They still sell the little kits at Summit to do it. The idea was to get the electrode facing the "kernel" for better combustion.


Also, racers do it on ultra high compression engines to keep the bend in the electrode away from the piston so it doesn't make contact.

And on a side note, years back I knew an old school mechanic who who had marked a whole bunch of plugs as to where the electrode sat, and he kept moving plugs around to where they happened to sit where he wanted them to sit, and he said his car ran real good...

 

[mechtech2]

Plugs were also indexed to 'point' the open unshrouded plug firing end at the most judicious spot in the CC for the best flame propagation.
What was this direction?
Tough call, because turbulence and flow changes the static picture.

Hotter ignitions with wider gaps lessened any need for indexing.