Main bearings, clearances, and feathered shims. Long.

[cliffh]

Sorry this is so long.

This my first Studebaker engine rebuild. I've got the series of TW articles on engine rebuilding and the Shop manual.

Got my '63 289 engine parts back from the local, father & son, great reputation, old-time style, automotive machine shop. Was told the crank was OK. Did the plastigage thing on the mains and got clearances that are a bit on the big side. Studebaker says .0005 - .0025.

I got #1 - .004 #2,#3,#4 - .0035 #5 - .003

The bolts were clean and oiled and torqued to 90 ft-lbs. The caps are clean. I redid it and got the same reading.

I went back to the machine shop and they pulled out their Clevite catalog which gives different clearances for each main.
#1 - .0010 / .0031
#2,#3,#4 - .0015 / .0040
#5 - .0011 / .0032

I pointed out that #1 wasn't even within the Clevite tolerances and the dad handed me a feathered shim to put between the cap and the insert. Has the same effect as grinding the cap. I never heard of a feathered shim so I did some googling.

http://books.google.com/books?id=_CADAAAAMBAJ&pg=PA146&lpg=PA146&dq=%22feather+shim%22&source=bl&ots=0gHkEbvUX-&sig=5g3dQyj3B4n_0Ptnxt2q0T3DGqo&hl=en&ei=okMQTOPrLZKUnQef0ICfDQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCUQ6AEwAg#v=onepage&q=%22feather%20shim%22&f=false

http://deckwartaperedshims.com/index.php

I tried the feathered shim on #1 and it took it down to .0025 but I don't want to leave it in there. Just seems too CASO to me. Anyway the other journals are still out of spec as far as the Stude manual.

I could have the crank turned. I checked 1 rod journal with plastigage and it was at .002 which is the Stude limit. (Clevite says .0030). Turning the crank and buying the main and rod inserts would cost about $245 less whatever I can sell my standard inserts for. I doubt SI would take them back since they've been installed.

So you all could vote by number on what I oughta do. Or make a different suggestion. I'm not going racing but I do like having good oil pressure. I just want a dependable driver that I can take on the highway for 200 miles without worrying about it. Probably won't put more than 1000 miles per year on it.

1. Get the crank ground and have them do both the main and rod journals while they're at it.

2. The machine shop has a bearing cap grinder. They could take .001 or so off the mains. This seems a little less of a kludge than the feathered shims.

3. Put it together the way it is.

What's your vote?

Thanks,
Cliff

[StudeRich]

Neither! Buy a set of NOS Studebaker .002 Undersize Main Bearings. That is assuming that the Crank is round! Was it measured at many locations? If not, just bite the bullet and turn that bad boy.

Someone will buy your new unused Std. Set.

[cliffh]

Neither! Buy a set of NOS Studebaker .002 Undersize Main Bearings. That is assuming that the Crank is round! Was it measured at many locations? If not, just bite the bullet and turn that bad boy.

Someone will buy your new unused Std. Set.

StudeRich. Thanks for the reply. Do you know where I could find a set of .002 undersize bearings? The chassis catalog lists #1555405 for a .001 undersize set but the only .001 set I could find on-line was at Studebakers West for $225. I don't see a part number for a .002 set.
Cliff

[StudeRich]

OPPS, sorry about that! .002 Under Main Bearings are in the Chassis Parts Catalog for Sixes, and -.002 V-8 Rods that I have used before also are, so I thought the Mains came in .002, but none are listed.

So unfortunately you are back to turning the crank to do it right, if the Rods do not need it, usually you can insist on only turning the Mains and maybe polishing the Rods.

[BRUCESTUDE]

A '52 Commander that I had up 'til about 6 years ago had a hot start problem, I tried everything to remedy this: rebuilt starter, new ground strap, big cable, clean all connections etc. This all helped, but after a hot run it still turned over too damn slow! I rebuilt the 232, and upon tear down I found the feather type shims in every main bearing cap. I didn't have a micrometer to see if it was out of round, but after having the crank ground and the proper bearings installed, it turned over perfectly! My theory is when the engine got real hot and everything expanded, the shims compressed things enough to tighten the crank up, and if it was out of round this would add to it. Possibly incorrect readings on someone's mike , or an attempt to bring up oil pressure? Anyway, there is no substitute for good machining and correct (round) clearances!

[Chipmaker]

Before turning the crank,check the hole in you rods,it is not unusual for it to go egg shape opening up the clearance.The fix is to machine a few tho. off the meating surface of the rod cap then remachine the hole round.

[Dan Timberlake]

Plastigage is not super accurate, but is an excellent check to see if things are in the ball park. A buddy went thru some pains to "calibrate" some plastigage readings measuring installed insert ID with a bore gage, but I don't remember if the PG read tight or loose, and that was a long time ago anyway so the recipe might be different now. First I'd do some tests on my batch of plastigage clamping some PG between two smooth blocks of steel (2 iron main caps?) with 0.003" feeler gages on each end.

It would be interesting to place a deburred piece of brass 0.003 inch shim on the oiled #1 crank journal, torque the cap, and see if the cranks still turns. Kits of shim stock used to be available for just that purpose.

http://books.google.com/books?id=_yYDAAAAMBAJ&pg=PA128&lpg=PA128&dq=engine+bearing+checking+shims&source=bl&ots=NsOvLbUUKt&sig=qQuAbavqro_r9OA_wIq5c1zJiX0&hl=en&ei=dc8RTLOhGoa0lQeS2NXOBw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCcQ6AEwAg#v=onepage&q=engine%20bearing%20checking%20shims&f=false

But sooner or later I'd carefully stone the block and cap faces to deburr them, clean, and assemble with the inserts installed, and use a bore gage to measure the ID to compare to the actual crank journal sizes. I don't think I'd trust shims to create a round bore or transfer heat nearly as well as an insert seating directly on the cap. If the crank journals are the right size, very round and taper free ( < 0.0002") I'd use it with that loose front main. If the rod and cam bearings are tight and the oil pump measures well, I'd expect the oil pressure should be OK.

There was a time when main bearings could be bought individually for most engines. Those were the days.

If there really is extra clearance I'd check the crank closer. Polishing can easily leave the journals tapered, so the clearance is several tenths tighter just at the edges, which is not a desireable situation.

Still have the old bearings? If the finish is good, you might like their clearance better.

[studebakerkid]

The feather shims are called shimstock and they are used when you want to get rid of the vehicle for a cheep way to shim the bearings so that you do not have a knock. I can not imagine anyone rebuilding an engine and then resorting to shimstock.

[Bud]

The cost of reconditioning the crankshaft isn't very expensive. I won't rebuild an engine without having the crankshaft turned, straightened and polished as I believe that the engine will last longer, run better and have better oil pressure if the crankshaft journals are round, smooth and have the correct diameters. Plus you don't have to look for scarce bearings to make up for excessive clearance. I've used shimstock in the past, but it is a band aid at best. Bud

[cliffh]

Thanks everyone for all the good information. I decided to go with Bud's advice and get the crank reconditioned. The machine shop here in Walla Walla doesn't do crankshafts themselves. He had several that he was hauling to Spokane today so by making a quick decision, I got free freight and a quicker turnaround.
Cliff

[PackardV8]

Hi, Cliff,

Call me. Maybe we can save this for you. 509-535-8610.

thnx, jack vines

[Dan Timberlake]

I'd ask them to magnaflux the crank before grinding it, and say I want sizes favoring the large size, less than 0.0002 inch taper, and the radiuses at the edges of the journal fully blended into the crank fillets.

After I get it back from the grinder I'd also measure all journal diameters looking for ovality and taper, check rod side clearance, runout of the snout, timing gear area and crank flange, deburr or even chamfer the oil holes, and finally do a light polish with dull 400 or 600 paper rotating the crank in the correct direction, or dual direction hand shoe shine polish. In the previous millenium I brought more than one freshly ground crank back to local premium grinding houses for issues ranging from sloppy to criminal.

Before assembly I'd be sure to clean the crank oil passages thoroughly. Gun cleaning brushes, or the smaller one from this kit from Mr Gasket do a nice job.

http://www.jegs.com/i/Mr.%20Gasket/720/1211/10002/-1?CT=999