spark plug discussion......for fentons

[claybill]

LOTS OF SIMPLE QUESTIONS..BUT i want to be on the same page as everyone helping.....

what plug reach is everyone using....?

how do you measure this plug reach.? I am assuming this is the thread depth?

my stock plymouth takes plugs with a short thread depth...maybe 1/2 in.

and my motorcycle takes NGK B8Es a longer thread reach.

obviously the electrode on the plug must be in the combustion chamber. why then is the electrode on the champion extended 1/4 in. more than the autolites? pistons/valves wont hit it? thats my fear.

how do you find the correct # for a longer reach plug that has the same heat range as the shorter.?

when using a fenton or shaved head do you change plugs?

bill

[james curl]

I had my head milled .090 and the top of the block surfaced. I run autolite 603 sparkplugs without any problems.

[martybose]

Reach is indeed the thread depth. The stock head takes a 3/8" reach plug, so far it seems that the Edmunds (mine) and Fentons (other folks) take 1/2" reach plugs. I ran an Autolite 306 until I figured out the reach issue, then switched to an Autolite AP425 which is 1/2" reach ( I called the Autolite tech line for their recommendation). Any variation in the 425 designation will be right, the AP is what I could find to try. But you do have to chase the threads first if you've been running 3/8" plugs for a while!

Marty

[claybill]

NOTE... the FENTON aluminum head is definitely a thicker casting than the stock head. and it requires a longer reach plug for sure. i am off to get a set of AP425's.

i will for sure chase the threads..as i cn see the last few threads are carboned up.

also an interesting note....the plymouth stock head has a shorter and shallower combustion chamber than the 230 dodge...guessing 10-15% less volume. sometime ago it was mentioned that the 41 head would make the 230 SING! i agree. it would raise the compression for sure.

i puton new plug wires this am..better.

i turned the dist clockwise, smoother. ( TO adj bolt limit)

things are looking up.

thanks all. bill

[martybose]

(snip)

i turned the dist clockwise, smoother. ( TO adj bolt limit)

If you've hit the movement limit on the bolt into the block, don't forget that there is also a range of adjustment on the bolt that goes up into the distributor housing on that same arm.

Marty

[claybill]

thanks marty.

b