As Dave mentioned, this is all a bit much with our cast iron head tractor
motors. I was told the main reason for changing the washer is not sealing
but consistent seating depth and heat transfer. When you get serious about
reading plugs on a high performance engine you change the plug every time.
You can't really read a used plug. I used to go through buckets of them
tuning one and two cylinder bike engines. You also index the plugs, and
the easiest way to do that is usually marking them and torquing them to
min spec and indexing without exceeding max (avoiding the temptation to
give it that last little shove past max). With a fresh washer you can turn
quite a bit without exceeding torque specs. Sometimes you need spacers,
but usually not. It makes a shocking difference in plug fouling with high
performance two strokes, where you want the outer electrode bend facing
the transfer ports (more or less) so it acts as a shield to keep the plug
from getting oiled. When you snap the throttle open on a two stroke after
a downshift you send a zesty blast of oil up from the crankcase through
the transfer ports. You'd think with the flat roof of the transfer ports
that the gas charge would flow across the top of the piston and curl back
(whatever didn't go out the exhaust port) to hit the plug anyway.
Whatever, it made a difference.
Some people index four stroke racing engines as well, pointing the
electrode towards the intake valves. They also do it for consistent head
volume. I suspect most people do it so that they wouldn't look stupid when
someone said "where do you index your plugs". No one has ever asked me
that at a vintage race. If they did I suspect I'd find ignoring them in
favor of a good book or a nap much more useful than fevered activity with
my plugs. I do enough goofy stuff as it is.
-----Original Message-----
From: Don Marshall [mailto:marshall@nefcom.net]
Sent: Thursday, April 10, 2003 2:44 PM
To: Bill Babcock; FOT
Bill, I checked with my local small town NAPA store. After numerous calls
to Champion, they found out they can get them in lots of 1,000 for about
$170 plus shipping, tax, etc. Net cost of about 20 cents each.
So, if I check the plugs after each session, figuring 2 sessions per day
over a 3 day event, and if I can do 6 events each year, it'll take over 27
years to use all 1,000. By which time I'll be 84 years old and probably
ready to quit racing anyway. Don
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Don Marshall'" <marshall@nefcom.net>; "FOT" <FOT@autox.team.net>
Sent: Thursday, April 10, 2003 2:24 PM
Subject: RE: Spark plug washers/gaskets
> Champion used to sell them in bags of fifty. I suppose the Napa store
> could order them. It was the Champion spark plug guy that used to come
> to the bike races that told me I should change them. I forget his full
> name, but everyone called him Bobby. Very nice guy and could read more
> in a plug than most people could in War and Peace. Of course then I
> saw him checking Kenny Robert's plugs on the new (then) OW31 Yamaha in
> the hot pits and sticking them back in with the same washers.
>
>
> -----Original Message-----
> From: Don Marshall [mailto:marshall@nefcom.net]
> Sent: Wednesday, April 09, 2003 4:52 PM
> To: FOT
>
> Has anyone got a source for spark plug washers/gaskets? I was taught
> to replace them every time I clean the plugs but I can't find them
> locally except with new plugs. As cheap as plugs are, I don't want to
> put new ones in everytime I want to check the mixture, etc. Thanks, Don
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