question on hardness of journals on early dodge cranks,

[30dodge35]

Question and opinions on older engine crank and piston journals hardness,

I have had this happen twice on 35 and 36 dodge engine , the number 6 piston journal will egg shape and loose oil pressure. Then engine develops a knock. After tear down ,both times number 6 journal egg shape and worn, other crank and piston journals are OK.

I had a old dodge engine mechanic tell me to get a 38 crank or older, due to the fact the journals are shot peen.

I have since then put a 1940 Plymouth engine after rebuild , it is working fine!! Many miles on it and still great oil pressure ,no knocking.

Jesse

[Machinist_Bill]

One way you could have cheated was to grind the journals 0.008" undersize, hard chrome 0.005" on a side (0.010" Overall) and then regrind to correct size.

You can't argue with success on your new engine!

[30dodge35]

Looking at it now, that would have been a cheeper and better fix

the local shop that fit crank to block, had grounded it undersize and fit bearings to crank and Pistons

when I was working on aircraft engines ,We would test cranks with Rockwell hardness tester, cranks had been shot peen to get correct harness

i don't have one available to test these

I don't know if It is fact or a Myth.

Edited May 9, 2015 by 30dodge35 (see edit history)

[Machinist_Bill]

In today's world the steel is of better quality and hardness. Heck the valves in my Overland are 2 piece. The valve is cast iron and the stem is hardened rod screwed into the valve head!

To shot peen will give some sort of surface hardness but is a lost art. Flame hardening, oil quenching, and induction hardening took it's place.

Good luck to you!

Bill

[30dodge35]

Not sure about statement of better metal

granted technology and processes are here to produce better quality steel and aluminum

but the need for profit causes the manufactors to produce metal that has been recyled and needs more corrosion protection

a lot of the newer aircraft and cars corrode from the inside out , intergrandular corrosion

[MikeC5]

Shot peening is still used on certain jet engine parts for resistance to fatigue crack initiation. The peening actually deforms or 'cold works' the metal at the surface producing compressive residual stress. This makes it less likely for a crack to start (high tensile residual stresses produce the opposite effect).

[Machinist_Bill]

Shot peening is still used on certain jet engine parts for resistance to fatigue crack initiation. The peening actually deforms or 'cold works' the metal at the surface producing compressive residual stress. This makes it less likely for a crack to start (high tensile residual stresses produce the opposite effect).

It has been a long time since I heard any discussion on tension/compression!

Thanks for the lesson Mike!

Edited May 10, 2015 by Machinist_Bill (see edit history)

[Machinist_Bill]

Not sure about statement of better metal

granted technology and processes are here to produce better quality steel and aluminum

but the need for profit causes the manufactors to produce metal that has been recyled and needs more corrosion protection

a lot of the newer aircraft and cars corrode from the inside out , intergrandular corrosion

I work for a company that recycles Aluminum. We melt it, put it through a caster, and roll it into coils for building products (Window frames, gutters, downspouts, etc) None of it flies to 35,000 feet or is used in the automotive industry. I take that back as we make license plates for 35 States. There is no way Ford would use our stuff on their F-150!

I am not sure about steel companies (NUCOR comes to mind) and if the automotive companies use recycled steel. I'm sure they have the same "Mix" problems that my company has. In our case too much iron or mag. Interesting topic!

One thing that baffles me is that the metal is paper thin yet a car hood can sit in the Arizona sun all day and not warp!

[30dodge35]

I have been doing a little research on crankshaft hardening, Discovered there are a few different aproaches to this process. Some have a deeper effect than others. With this information and available bearing undersizes gives the machinist the infomation needed to determine how much a crankshaft can be ground undersize.

I remember my crankshaft was ground to undersized and fitted with bearings by a local shop.

This being said , the posibility of crank being ground too much and hardening being removed, I don't know if machinist re harden shaft after grinding.

The he crankshaft in the 1940 Plymouth engine was standard.

Still can't find the process used in 1935, verses later years, still a myth verse fact??

[30dodge35]

http://www.crankshaftco.com/steel-crankshaft-hardening.html

This is a article from crankshaft specialist

I think the older cranks were Nitrided harden

When mine was ground ,the hardness was removed,