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wjohn 
Orange Level
Joined: 19 Jan 2010
Location: KS
Points: 1801
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 Posted: 13 Mar 2022 at 9:55pm |
Sorry to hear that. I hope you're recovering okay. I have definitely enjoyed following along here and want to see it back together and running.
For what it's worth I found that some similar-era lifters were only carburized in the .030-.040" deep range. Doesn't mean that's what AC did, but personally, I am thinking taking more than .020" or definitely .030" off the lifter face is starting to get into questionable territory. I think you made the right call on that one lifter. I need to go back and re-measure my WD lifters to see how much I ended up taking off, and see if I had to go too deep to clean them up.
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1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45
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ac55tractor
Silver Level
Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 03 Apr 2022 at 7:03pm |
My surgery was successful. I have been able to sneak off, and I been doing some stuff in the cellar. An hour or so here and there is a lot better than sitting around.
We have two seasons here in Maine, Winter and Mud season. We spend Mud season getting ready for winter. I am anxious to get outside and to my 4 Simplicity garden tractors.
While I was recovering, I contacted an old friend and sent out the #8 lifter (tappet) to him. He programs (C.N.C.) computerized machinery for a large machine shop here in Maine. They have a Rockwell hardness tester. I asked him to check the center of the round flat and the body diameter of the lifter. I can rattle off some numbers, but they won't mean very much. The lifters are hardened, but not as hard as a hand file.
After grinding off roughly .030 off in my milling machine and grinding off another .015 or so with a 4 inch angle grinder. The round flat of the #8 lifter, measured virtually the same, as the lifter diameter or within one point on the Rockwell "C" scale. In reality we don't know what they are made from, but they are hardened throughout.
I think that is the important thing for us all to know. I asked him to toss the lifter out after he was finished with the test.
I finished my camshaft. here.
Steve (in ME)
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ac55tractor
Silver Level
Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 03 Apr 2022 at 8:27pm |
 This picture was taken before I sent off the lifter for testing. I have since resurfaced the one with the rust. Steve (in ME)
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wjohn
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Joined: 19 Jan 2010
Location: KS
Points: 1801
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Posted: 03 Apr 2022 at 11:07pm |
Sounds like good news for you - glad to hear it.
I'd be curious to know the Rockwell numbers if you have them. From what been able to gather, it was fairly common for lifters of the era to be hardened to .030-.060 deep. It would be really interesting if the AC ones were hardened throughout or made out of a harder base material with no post-machining hardening.
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1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45
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ac55tractor
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Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 04 Apr 2022 at 6:56am |
The flat tested at 56 Rockwell C and the body diameter came out at 57 Rockwell C. >  < Most of the hand files that are made today are made from high carbon steel and are hardened to 62-66 Rockwell C.
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IBWD MIke
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Joined: 08 Apr 2012
Location: Newton Ia.
Points: 3452
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Posted: 04 Apr 2022 at 8:22am |
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At work we have a 'PMI gun', I think that's what it's called. Anyway, it determines what material things are made of, very specifically. I'll take a lifter to work and have an inspector 'shoot' one and see what it's made of. I'm rather curious myself.
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ac55tractor
Silver Level
Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 04 Apr 2022 at 8:43am |
That's a great idea. I have been thinking about the Rockwell hardness of that lifter. It seemed a bit hard to me. But then I realized that chances are, the lifter may be harder than the camshaft, but the mating surfaces are both ground smooth. Along with the layer of oil between them, there really is no reason why they should wear themselves out. Sure they wear out in time, but I think if the tractor has regular oil changes, the parts should last a lifetime.
Just a bit off topic. In the late 60's and early 70's, Chevy had a problem with soft camshafts in their 307 engines. They would ware out prematurely.
Steve (in ME)
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IBWD MIke
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Joined: 08 Apr 2012
Location: Newton Ia.
Points: 3452
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Posted: 04 Apr 2022 at 10:59am |
That hardness doesn't surprise me. Had it been much less, that would have surprised me.
I'm going to guess that the lifters are 1040 or something close to that. A shop I used to work at made lots of pins, 1040 can be induction hardened rapidly. I'm sure there are several other steels that can too.
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ac55tractor
Silver Level
Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 04 Apr 2022 at 7:55pm |
1040 steel would be a good choice. It's machinable, with good tensile strength.
I am so glad that "IBWD Mike" is able to help us nail down just what material we are dealing with.
For now, I am moving on to the next part of my rebuild.
I noticed that I had two stripped out head bolt holes in my engine block. I covered the block the best that I could with duct tape to keep the cast iron chips out of the crank case, and repaired the holes in my drill press with 7/16-14 Heli-coils.
First, I measured to see if the block would fit in my drill press. I strapped down the block onto the base of the drill press, lined up each hole with a regular "on size" 7/16 tap as shown, drilled, tapped, and inserted the coils deep enough, so if the top of the block had to be resurfaced the coils would not interfere.
I am still not an engine re-builder.
My best advice is, if you haven't done this sort of fix with
Heli-coils before, don't attempt it. Just to be clear, leave this job to
someone that you can trust to do it right the first time. I can't tell you how many of these I misaligned when I was younger with the shop foreman looking over my shoulder.  Also, pulling the coils out after a misalignment can be a nightmare.
Steve (in ME)
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IBWD MIke
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Joined: 08 Apr 2012
Location: Newton Ia.
Points: 3452
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Posted: 06 Apr 2022 at 1:27pm |
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Well, the gun didn't give us the number of the steel. It did give a very specific chemical breakdown. For whatever reason it does not read carbon content. Between google and Machinery's Handbook, I'm going to say 1040 is the most likely candidate.
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ac55tractor
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Joined: 20 Oct 2012
Location: Raymond, Maine
Points: 240
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Posted: 06 Apr 2022 at 3:09pm |
Thanks for your efforts Mike. Maybe someday someone can come up with an answer on the material. For now, I am going to run my lifters, they all have plenty of "beef" on them. The thin one (#8) is gone. So there is no worries on my end. As far as the rest of them go, I may have only removed .010 or so.
Funny thing is that even though #8 lifter was warn out, The #4 lobe on my old camshaft was warn short. I am going to take a guess here. I could be wrong, but I don't think that #4 and #8 were getting enough oil.
I am glad that there are guys like you out there that support the rest of us.
I pulled out my cam bearings today and I am going to replace them. I scratched the first two when I removed the camshaft last time. Unless some one has a better Idea, I think that I am going to clean the cam real well, and cover the lobes with 2 or 3 layers of painters tape and reinstall the camshaft.
Thanks again  Steve (in ME)
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