Early 1/2" reach plug heads take L series Champion plugs and are ientified
by the number 22952 ( as I recall ) cast into the front right top corner of
the head.
Late heads use 3/4" N series Champion plugs and have the number 168XXX
stamped into the front right top corner of the head..
Yes it is important to have the right plugs.
Bob Grunau
Canada
Nels,
If it is a 1953, and if the cylinder head has not been replaced by one from
an earlier TD (or TC or TB), then you're using the wrong spark plug. The
late TD/TF head requires a plug with a 3/4 inch thread reach (Champion N
series). The L series plug you're using has a 1/2 inch thread reach. In the
late head, an L series plug's electrode is recessed into the lug hole, so is
shrouded and not exposed to the full blast of combustion and will foul.
If you aren't sure which head you have, there are visual clues that I don't
remember off the top of my head. Nor do I remember the correct current N
series plug. I'm away from my books and notes this evening so can't look
them up. Hopefully someone else will chime in, but if not I'll post the info
later.
Another way to tell is to bend a piece of stiff wire into an el, with the
bottom leg of the el very short. Insert it through the plug hole and hook it
at the bottom if the hole. Mark the wire parallel to the plug seat. Pull it
out and measure to the mark.
If it turns out that you do have an early head on your late TD then the L
series Champion is correct, but L82YC is colder than normal. L87YC is better
for most standard XPAG engines, or the equivalent heat range from another
maker.
--
Chip Old
Via iPhone Mail
On Jun 29, 2010, at 6:13 PM, Nels Anderson <nels@flightsim.com> wrote:
> It seems that as long as I've had my '53 TD the spark plugs have fouled on
a regular basis. Last summer I had the carbs professionally rebuilt and
adjusted and expected that to solve the problem. But today I tried to drive
the car and it was running so rough I turned right around and went home.
>
> I pulled the plugs and found #3 fouled (black material between points) and
#4 somewhat caked with black material but not fouled. #1 and #2 were black
but not so bad looking. This is pretty much the same thing I used to see
before the carbs were rebuilt.
>
> Carbs were rebuilt last September, 1300 miles ago.
> Plugs were new last September, 1200 miles ago.
> Ignition wires were new in 2007.
> Distributor cap, etc. new in 2004.
>
> So I'm wondering what I can do to reduce this fouling? Would hotter spark
plugs work; I'm currently using Champion L82YC. Would a sport coil help
(hotter spark)? And if so, I believe the plugs have to be regapped; to what
setting? Currently they are gapped between .020 and .022 according to the
book.
>
> Thanks for any help.
>
> --Nels Anderson
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