Engine: Oil Pressure and Bearings

[mjeansonne]

Many years ago (about 35 years), I rebuilt the 6 cylinder engine in my 1954 Champion (which I longer have...) I had the crankshaft journals turned .010. After the rebuild, the oil pressure was still very low, reaching only about 20 lbs at 40 mph. Tested it with an external oil pressure gauge and it was sill low. So I rebuilt it again. The journals and the bearings showed considerable wear in only a few months time. Took extra care to keep everything exra clean. Oil pressure was still low as it was previously. My Machinist suggested that perhaps Studebaker had 'surface hardened' the journals and that is what we should have done, but didn't.

I am rebuilding my first Studebaker engine since that time and am concerned about the hardness of the journal surfaces. This engine is a 1963 full-flow 289 V-8, non Jet-Thrust. The same machinist that did the machine work 35 years ago is the same machinist that is doing the work now. He said when he turned the crank (again to .010) he got lots of sparks and so the journals seemed to be of good steel. He remembers the problem we had with the 6 cylinder crankshaft. This is the first time the engine has been rebuilt, everything initially measured out from standard sizes, though well worn.

My question is, do we need to be concerned with the hardness of the journals after having turned the the bearing surfaces down .010? I don't want to have low oil pressure.

Thanks for everyone.

[1954khardtop]

Mike, I sent you a PM earlier, did you see it?

[jackb]

is his old machine up to turning that crankshaft down ? ....there shouldn't be a problem...Its been discussed here that Studebaker engines were no harder than the competition....folklore...Your flathead probably suffered from lifter bore wear...

[jclary]

No mention of cam being replaced...just saying...???

[StudeRich]

The V-8's do not have the issue of Valve Lifter bores being worn out early on like a 6 Cyl.

HOWEVER all Engines are subject to Cam Bearing wear, as mentioned already, those should always be replaced, if you did not on the 6, one or both of those conditions caused your dual failures.

The Stude. cranks are harder than ordinary other makes' steel cranks, being Forged iron like older Fords.

[mjeansonne]

The cam bearing were replaced both times on the 6, so that wasn't the problem. I always suspected that maybe it was because the main journals on the 6 prior to 1955 were a much smaller diameter than those post- 1955. Don't know, but just a thought. Haven't owned a 6 since then.
With the V-8 going back together now though, it brought back those recessed memories of the problems I had with the 6, so I told my machinist I was going to pose the question concerning the journal on the V-8. As indicated initially in my first post, He stated that he thought the crank journals were indeed hard because of the sparks emitted. Not being a machinist I can only rely on his expertise... whatever sparks have to do with it!!!

[tbredehoft]

Steel with the capability to be hardened had different (smaller and whiter) sparks than plain low carbon steel, whether it has been hardened or not. This could be what he was seeing.

[PackardV8]

My Machinist suggested that perhaps Studebaker had 'surface hardened' the journals and that is what we should have done, but didn't.

No, it's not necessary to surface harden a Studebaker crankshaft after a typical regrind. Yes, agree, your 6-cyl low oil pressure was most likely from the cam bearings and/or lifters. It wasn't from grinding through the "surface hardening."

The Stude. cranks are harder than ordinary other makes' steel cranks, being Forged iron like older Fords.

In a discussion of metallurgy and technology, correct terminology is necessary. Studebaker crankshafts are of forged steel, not "Forged iron."

FWIW, every major manufacturer, GM, Ford, Mopar, AMC, made or still builds millions of engines with forged steel crankshafts. That a crankshaft is forged does not in and of itself make it "harder." It depends upon the alloy of the billet from which it was forged and the heat treating it received afterward.

Yes, Studebaker forged crankshafts are stronger than the typical cast steel cranks used in many other economy car engines of the era. This isn't because of the "hardness" but because forging gives an inherently stronger grain structure than casting.

No, they're not harder than the forged cranks used by other manufacturers. Millions of 283" Chevys of the same period had forged steel crankshafts.