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Plymouth Tappets


Guest baggersbailey

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Guest baggersbailey

Looking at the tappets on my 1938 Chrysler Wimbledon (plymouth p6 in the US) No1 inlet has a gap that I could crawl through, I can adjust it with my fingers, so what stops it self adjusting again ? Cheers from the UK

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Looking at the tappets on my 1938 Chrysler Wimbledon (plymouth p6 in the US) No1 inlet has a gap that I could crawl through, I can adjust it with my fingers, so what stops it self adjusting again ? Cheers from the UK

Isn't there a lock nut on it?

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Doesn't require a lock nut.

Depends on the year. Parts book shows a lock nut on 1938 and earlier engines. Part number 40819.

In 1939 they changed the adjusting screw from part 70774 used on earlier engines to part 681544 used on later and the later adjusting screws don't show an associated lock nut.

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Depends on the year. Parts book shows a lock nut on 1938 and earlier engines. Part number 40819.

In 1939 they changed the adjusting screw from part 70774 used on earlier engines to part 681544 used on later and the later adjusting screws don't show an associated lock nut.

And that is why I asked.

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My MoPar Master parts book shows part #681544 screw used from 1928-1954 for all six cyliunder car lines. Not that it matters.

Interesting. My parts books end at 1948 so it sounds like you have a newer book. Since the tappets have the same number from at least 36 through 48 I can see that 681544 would fit in an older engine. I am guessing that 681544 is in some way self-locking while the older 70774 is definitely not.

I wonder if who ever put the engine together for the original poster had your parts book so assumed all the tappet screws were the same. But the tappet screws he used were the older ones which needed nuts.

Looks like both the older and newer parts are available through several vendors on PartsVoice.com so which ever ones are needed to fix this engine can be acquired.

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That 681544# probably came out in mid 30's? So Mopar cars must have used those self locking tappet screws in the mid 30's too. I've never seen anything else on hundreds of Mopars late 30's on up that I have worked on over the years.

I wouldn't want to deal with lock nuts when adjusting tappets on an old flathead!

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. . my 1938 Chrysler Wimbledon (plymouth p6 in the US) . . .

I believe that the '33 Plymouth was sold in England as a Chrysler Kew 6. I assumed that was true for other years too and that models like the Wimbleton were rebadged Dodges or DeSotos. I guess that was a bad assumption.

Do you have a cross reference for the mapping between US and UK models?

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That 681544# probably came out in mid 30's? So Mopar cars must have used those self locking tappet screws in the mid 30's too. I've never seen anything else on hundreds of Mopars late 30's on up that I have worked on over the years.

I wouldn't want to deal with lock nuts when adjusting tappets on an old flathead!

Doing the exhaust on #6 can be a bear and you really do need tappet wrenches to do it. Later cars had a removable panel in the wheel well so maybe getting to #6 would be easier, but on my '33 you come in from over the fender. I probably don't check them often enough and it has been years since I actually adjusted them. So long that I don't remember the details but I vaguely recall having the tappet wrenches on the tappet and lock nut in my left hand and going between a regular open end and the feeler gauge with my right. Mostly what I recall is getting burns from the hot manifold as I couldn't manipulate the wrenches well enough with gloves on so I end up doing it bare handed.

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Guest baggersbailey

That's the way I read it Rusty. Am going to try thread locker for a start, but getting ready for a big strip. See if it works while I wait for some new followers. Cheers from the UK

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May not be necessary to strip the engine. If you can lift the valve with a valve spring compressor there may be room to remove and replace the tappet screw.

The tappets are mushroom type and can only be removed after removing the camshaft.

Worse comes to worse, you can remove the head and the valve and valve spring which should give you plenty of room to get the old screw out and a new one in.

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