Case hardening?

for those with Series MM sidevalve cars produced between September 1948 and February 1953
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Mick Lynch
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Case hardening?

Post by Mick Lynch »

The adjuster screws on the tappets have a degree of wear and pitting. I have rubbed most of them flat with carborundum paste (checked them with blue for low spots and a hand mic to ensure they didn’t deviate from the perpendicular).

Should they be case hardened prior to re-erection?

If so it’s not something I have ever done; anyone got experience? Local ironmonger sells case hardening powder.
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philthehill
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Re: Case hardening?

Post by philthehill »

If you have the means of case hardening the adjuster screws they should be case hardened.
Here is a good explanatory video on case hardening:-
https://www.youtube.com/watch?v=f_bXiIfcBWs
An easy way of getting the heads of the tappets flat and square is to mount the tappet in a pillar drill chuck, put a piece of oiled emery cloth on the table and push down the chuck and tappet onto the oiled emery cloth. the head of the tappet will be smoothed and flat. Just make sure that the table is square to the chuck by mounting a piece of rod in the chuck and checking with a square on at least two sides.

Mick Lynch
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Posts: 219
Joined: Sat Sep 12, 2020 9:20 pm
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Re: Case hardening?

Post by Mick Lynch »

I got them case hardened. Seems to have went well.
No8 tappet screw
No8 tappet screw
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I used Kasenite No.1 powder. It’s used by gunsmiths for firing pins but has many other engineering functions. Time will tell if they are more successful than leaving as is.

You can see the remains of the ‘shell’ in the powder for one that fell off and I had to do again.
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