Engine: 289 Rod/Main Journals

[345 DeSoto]

Took measurements of my 289 (Sky Hawk) rod and main journals. Rod journals are 2.00 inches, and mains are 2.500...both, right on the money. My Wife (A-1 Machinist) did the measuring using HER micrometer. Can I use STD rod/main bearings, or do I need to go oversize?

[karterfred88]

Took measurements of my 289 (Sky Hawk) rod and main journals. Rod journals are 2.00 inches, and mains are 2.500...both, right on the money. My Wife (A-1 Machinist) did the measuring using HER micrometer. Can I use STD rod/main bearings, or do I need to go oversize?

What's wrong with the ones in there. Get some plastigage and check the clearances. Looking at those heads, it looks like this 289 was gone through pretty well before.

[StudeRich]

If they measure Standard which they do, they would take STD. Size Bearings if damaged somehow.

If you use .010 UNDERSIZE Bearings you will lockup the Crankshaft, there ARE no Oversize Bearings made for Engines.

[swvalcon]

If you are right at std you should be fine with new std bearings. Now if it was worn just a little and checked out at .001-.002 undersize they also make .001 and .002 under size bearings for that any more than that you need to regrind the crank or if it's way out of round. I always check each journal in three or so spot around each journal to see if it comes up the same.

[Dan Timberlake]

Yeah, at least 9 different measurements are needed on each journal to qualify its condition.
Also checking all the main journals for runout (crank straightness) with a dial indicator while turning the cranks slowly while supported in the front and rear main bearings in the block, or some greasy wooden V blocks.
And I'd check for cracks using the wet fluorescent mag particle method before considering it suitable for use or regrinding.

[swvalcon]

Dan True but checking for run out and cracks is most times done by the crank regrind shop.

[PackardV8]

And I'd check for cracks using the wet fluorescent mag particle method before considering it suitable for use or regrinding.

Dan True but checking for run out and cracks is most times done by the crank regrind shop.

Interesting that I just had this discussion about a Packard V8 forged crankshaft. None of the crankshaft grinders here in Spokane wet mag cranks. The experienced machinists say they can tell by the "ring" when tapped with a hammer. If a customer wants it done, we can dry mag, which is better than nothing.

All the grinders do have crank presses to straighten run-out. It's usually only necessary when a crank has been welded up to save a badly scored journal.

FWIW, I've never seen a Stude V8 crank cracked which didn't show extreme heat bluing on one or more journals.

jack vines

[345 DeSoto]

STUDERICH - So use to thinking oversize for pistons, but you got the point.

[wittsend]

STUDERICH - So use to thinking oversize for pistons, but you got the point.

Well, it could be said that the bearing material itself is "oversize" (thicker). But, no, no one usually discusses it in those terms.

Which reminds me of the time I went to the bike shop as a kid to get a left pedal. The owner who had a Chet Huntley voice Asked, "So you want a left pedal?"" To which I answered, "Right." And he said, "Oh, you want a right pedal?" To which I said, "No, I want a left petal." To which he said, "So, you want a left pedal." And I again said, "Right." And he said, "So you do want a right pedal. .... This went back and forth about five times before he was probably feeling sorry for me in that I was too naive to get it. Eventually he got it right, I did get a left pedal.

[swvalcon]

Jack that is how my dad use to do it with a small hammer and in later years as his ears where not so good he would dry mag some.

[doofus]

In the 80's FoMoCo built some engines with OVERSIZE cam bearings. they were used to save some factory engines and no standard cam bearings would stay in block, the cam bearing driver would push them right on through. we wound up reusing the old bearings. enging had good oil pressure with std pump and lasted many years in Yeoman Service to a fellow Guard member.A CAFO for sure! Luck Doofus

[Dan Timberlake]

...................
FWIW, I've never seen a Stude V8 crank cracked which didn't show extreme heat bluing on one or more journals.

jack vines

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I think there are a few tales on this board about folks whose V8 cranks broke in service, some presumably original.
http://forum.studebakerdriversclub.c...t=broken+crank

Didn't larkgirl have a V8 crankshaft break in service too ?



I'd bet any one item off the dollar menu that the break would have been visible as a mere "indication" using wet mag particle a few months/years earlier.

[Mrs K Corbin]

well, it could be said that the bearing material itself is "oversize" (thicker). But, no, no one usually discusses it in those terms.

Which reminds me of the time i went to the bike shop as a kid to get a left pedal. The owner who had a chet huntley voice asked, "so you want a left pedal?"" to which i answered, "right." and he said, "oh, you want a right pedal?" to which i said, "no, i want a left petal." to which he said, "so, you want a left pedal." and i again said, "right." and he said, "so you do want a right pedal. .... This went back and forth about five times before he was probably feeling sorry for me in that i was too naive to get it. Eventually he got it right, i did get a left pedal.

and who's on first!