Anyone with experience using these tappets please

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
bowman
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Anyone with experience using these tappets please

Post by bowman » Tue Sep 20, 2022 4:23 am

I have a bunch of these NOS tappets that I'm about to use in an MB rebuild. They are supposed to be compatible but an online search seemed to suggest they weren't case hardened like the originals. Original factory tappets seem to be hard to find these days. Anyone have any experience using these in a running engine please? Is the lack of case hardening a big issue?

Image

Also, would be great to see an official reference to compatibility if anyone has one of those cross reference guides please?

Thanks!


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Re: Anyone with experience using these tappets please

Post by Adam » Tue Sep 20, 2022 6:50 am

Whats not hardened on them, I may have some of them too, put a copy of the post that says so on here.

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Re: Anyone with experience using these tappets please

Post by bowman » Tue Sep 20, 2022 2:43 pm

I was running part number searches on the PartTarget.com site Adam. It says the face is case hardened on the 637047 item.

Here are the 2 data sheets for the factory part 637047 and the later service part 804773.
637047.png
804773.png

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Re: Anyone with experience using these tappets please

Post by dpcd67 » Tue Sep 20, 2022 3:19 pm

You can't have a lifter that is not hardened; it won't work. Try to file it; if you can't, then use it. If you can, throw them away. Who would make a lifter that wasn't hardened? Not counting current Chinese ones.
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Re: Anyone with experience using these tappets please

Post by Adam » Tue Sep 20, 2022 5:11 pm

What is considered the face? will do some searching tomorrow, I use a center punch. if it flies off its hard.

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Re: Anyone with experience using these tappets please

Post by dpcd67 » Tue Sep 20, 2022 7:10 pm

The face is where it meets the cam lobe.
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Re: Anyone with experience using these tappets please

Post by Ralph » Tue Sep 20, 2022 8:17 pm

I used those on an MB rebuild in 2013...with a NOS cam.Ran it in with some Zinc treatment, no problems.
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Re: Anyone with experience using these tappets please

Post by bowman » Thu Sep 22, 2022 4:24 pm

dpcd67 wrote:
Tue Sep 20, 2022 3:19 pm
You can't have a lifter that is not hardened; it won't work. Try to file it; if you can't, then use it. If you can, throw them away. Who would make a lifter that wasn't hardened? Not counting current Chinese ones.
Good question. Maybe one uses 100% hardened steel and the other uses a case hardening process to achieve local hardness where it matters? These are genuine jeep service parts so I guess they must be acceptable. Perhaps wartime parts had a little extra hardness to cope with massive abuse in the field?

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Re: Anyone with experience using these tappets please

Post by bowman » Thu Sep 22, 2022 4:24 pm

Ralph wrote:
Tue Sep 20, 2022 8:17 pm
I used those on an MB rebuild in 2013...with a NOS cam.Ran it in with some Zinc treatment, no problems.
Thanks Ralph, good to know.

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Re: Anyone with experience using these tappets please

Post by W. Winget » Thu Sep 22, 2022 4:58 pm

Just another opinion, I'd rather have the lifter need adjustment to the wear, than replace a cam that is worn down from a harder metal riding on it.
So yeah, I'd use them.
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Re: Anyone with experience using these tappets please

Post by dpcd67 » Thu Sep 22, 2022 5:12 pm

Wear on a lifter is always bad: no amount of adjustment will restore the dome shape which makes the valves rotate. And I have seem them worn flat.
One clue is the type of steel listed; the top one is in the 5000 range, which is Chrome moly, with a higher chrome content, and low (.2%) carbon which means it has to be case hardened to work. Meaning it has to have added carbon to make it hard and it even specifies the face.
The bottom one is far less descriptive, calling out only "steel", which means nothing. So, it might contain enough carbon to allow it to be hardened without adding carbon through case hardening process.
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Re: Anyone with experience using these tappets please

Post by parker007 » Thu Sep 22, 2022 5:14 pm

your options now are getting slim. not much lifters on market.

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Re: Anyone with experience using these tappets please

Post by W. Winget » Thu Sep 22, 2022 7:31 pm

So being mil spec and purchased for the military fleet of vehicles, one would suppose it's not of high enough quality to use in a rebuild, go figure.

PDF description with NSN:
https://aerobasegroup.com/pdf/nsn/2805-00-933-3554.pdf

Piece as described by another dealer listing it as oversized:
https://www.vintagejeeps.com/p-1482-tap ... 19703.aspx
Looking for 1918 Standard B 'Liberty' truck parts

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Re: Anyone with experience using these tappets please

Post by dpcd67 » Fri Sep 23, 2022 8:56 am

It says not Casehardened; does not say it is not hardened. Why doesn't someone check one? Easy to tell; one way is as Adam said; try to scratch with a center punch. Or a pocket knife. Or a file. You will know right away if it is hard or not.
Case hardening is only for low carbon steels. Steel with a higher carbon content can be hardened without adding any more carbon. The top one, as I said, has only .2% of carbon in it, so it will not harden by itself; it needs extra carbon added; that is what case hardening does.
If it were made from a higher carbon content steel, having the third number 4 or higher, it would harden with no addition of carbon; IE, heat and quench; it's hard.
So, in reality, we don't know.
The Army would not purchase soft tappets; at least no reason to....
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Re: Anyone with experience using these tappets please

Post by Adam » Fri Sep 23, 2022 5:03 pm

4773 tappets, pic did not come out. file slides off the side surfaces and off edge of face.
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