Indexing your plugs...

[Hodgie1013]

Has anybody tried indexing their spark plugs? I'm going to give it a shot and see what happens. I know the "Falcon Six Bible" makes mention of it but only briefly and not too detailed. I bought some Autolite 5125s. They're a couple heat ranges cooler than stock to work with my ignition setup, and have and extended tip. I'll also open the gap a little over what stock calls for. Maybe .005 or so. I generally opt for Champions but they didn't have what I was looking for in stock. Just curious if anybody has any input about this subject. I'll post results if they're worth posting.

Here's a little info for those who may not be familiar:
http://www.fordmuscle.com/archives/2000/07/indexplugs/

 

[LaGrasta]

I tried it.
First, you have to have extra copper washers to help seat/align them correctly. Second, it made no difference at all in terms of mpg or seat-O-the-pants.

 

[LaGrasta]

It might be good to try any number of the new multi tang spark plugs out on the market now. Essentially, they do the same thing as indexing, pointing the spark in a more appropriate direction (i.e. all directions).

 

[addo]

I had one motor where it was crucial. If the electrode pointed up, the piston tapped it closed.

 

[blueroo]

I noticed one difference...it runs smoother

 

[falcon fanatic]

I've tried it on a number of engines. The only one where I noticed a seat o the pants difference was my Civic SI. It was an autocross car and had all the usual engine mods, header, cam, etc. It made a real difference, but that car was very sensitive to what brand plugs I used, too. It only liked Nipondenso u-groove. I suspect the message there was that I needed a more powerful ignition.

 

[rbohm]

8) years ago when plug indexing was all the rage, we tried it on our race car, and found no difference in performance. but because the driver said he liked the feel of the engine with indexed plugs, we took the time to do it. we ran B/Fuel Altered.

 

[powerband]

Hey if it makes you more comfortable that you went that last 99% after the first 99% for performance - then go for it.

The Clifford built 250 in the '61 shows the labor intensive care taken by true builders. I have some pics I took for the machinist when investigating how it was put together.

Indexed plugs might be needed to prevent piston/valve interference, or may be helpful in efficient flame combustion spread. Either way, I keep rotating a set of 12 plugs until I get of the indexes most correct ...

Heres''s the "Mothballed" Clifford 250 pics as built with index marks:

Powerband

Jack Clifford, legendary six cylinder racer, record holder and engine builder's shop built this performance 1975 Ford 250 six engine and then it was crated and "mothballed" for years - 10:1 Pistons-.070 overbore, Clifford matched shot peened rods, Clifford 272H Cam, line bored & balanced bottom end, Cloyes timing set, Melling pump, Fisher performance balancer, 1.88 int. valves, Ported and relieved, Offy 3X1 w/3 progressive modded Holleys @ 600 CFM at WOT, Re-curved distrib., Hooker long tube dual out headers = the works =, a few mysteries...