I have an original 1920 model TT engine with no spark plugs currently. I would like to clean the threads but can not find what would be the correct spark plugs for this engine. I see that there are different brands but no size listed. I would would like to run a tap down to clean the threads before installing the correct plugs. Does anyone know where I can find the correct plug size & brand for this engine? Thank you
1/2" pipe - don't run the tap in too far !
Its pipe thread.
As far as brand is concerned, there are several. Probably the most popular is Champion X, which has been been used in Model T's for about a hundred years. The new ones are about $20 each at O'Reilly, but you can find good used ones for a lot less. Here's one earlier discussion of plugs: http://www.mtfca.com/discus/messages/257047/281658.html?1334294429. With a Google search you can find more.
Joni,
CAUTION: The pipe threads seal the plug. It does NOT run down and seal with a copper gasket etc. As Steve said above: "1/2" pipe - don't run the tap in too far !" I would recommend cleaning them with a wire brush etc and see if they seal up ok with the plugs.
Disclaimer -- there are some reproduction heads that use the 14mm modern plug size and Ford produced some heads with metric threads for export -- you do not normally find them in the USA cars.
Respectfully submitted,
Hap l9l5 cut off
i second the opinion of cleaning with a brush, you could get in trouble fast with a pipe thread.
a good hardware store sells gun brushes, buy one that fits and brush it out good. if you have crap in it that wont go away with a brush, then run the tap down until you feel it grab, and NO MORE, the object is to not remove any material, just the rust and junk.
seeing the price the crappy autolites and champ 25s i would go with the repro champion X's. they are quite expensive, but they will last longer than you.
A battery cable terminal wire brush cleaner works really well. You can get them a harbour freight or any auto parts store. 99 cents to maybe 5 bucks.
I put never seize on my plugs and crank them down. Stay away from Autolite. The porcelain won't stay tight once they get hot. Motorcraft or Champion are good. If you insist on running the tap down be careful you don't get any threading shavings down in the engine. I'd just put a battery cable end brush in there and clean them out.
Thank you for all your responses. I will try what you have suggested.