Indexing

[daredevil]

Just wondering how many of you guys index your plugs and at what area of performance does it make a real difference.

 

[3404spdvaliant]

Mine are indexed off center toward the exhaust valve.
Probably worth 2-5 hp in my case being the sb heads have the plug angled to the exhaust valve already which is ideal.

 

[daredevil]

How do you do yours? different spacers under the plugs or carefully crush the aluminum washers till correct on initial installation?

 

[3404spdvaliant]

Well I had about 12 spark plugs including the ones in the car, so what I did was with a marker draw a line on the plug marking where the open side of the electrode was[or 180 to the strap] then with all plugs out of the motor, [so to have many available] started screwing them in till I could get'em one at a time to end up where I wanted them to point
[off center to the exhaust valve] that way eventually you will get a plug that lines right up given it's in the right hole with out washers.

So outta 12 plugs I got them all indexed with no washers.

All of the plugs and threaded holes were/are clocked different when tapped/dyed.

 

[daredevil]

thanks ,makes sense. Im gonna do this on my new motor. As much as i,ve spent i want every horse. I wonder how common this is with non racers

 

[dusterdon]

actually with the powerful ignition systems we have now, indexing the plugs isn't the big deal it used to be, but i guess it can't hurt anything.

 

[daredevil]

direction of initial flame travel does make a difference. top fuel cars use indexing as a tuning tool

 

[abodyhotrod]

for any racing app. indexing is recommended, i just indexed mine w/ the heads off.

 

[3404spdvaliant]

I will do this to every mopar I own, it almost costs nothing [4 extras,spares?].