Main bearings

[Deleted User]

Does the 8 cylinder stepdowns Have inserts for the crankshaft? I know my 6 cyl.jet does. I am still new to the Hudson's, I know too some of you this probably sounds like a dumb question. Just curious.



Thanks, Barry Smedley:o

hudsonguy

Barry,



Stepdown Hudson 8 engine's do indeed have poured Babbit bearings, rather than replaceable shell inserts found in the sixes.

[Deleted User]

My Brother-in-law has a 51' commodore, 8 cyl. When he starts it up cold he says he can hear a main rattle for afew secounds. The car has 50,000 miles on it. He has adjusted the valves and dropped the oil pan and cleaned out the sludge, ( it was very dirty) It runs very smooth and has good pickup. Should he start worring about that rattle, or is this just a Hudson trait with the babbit set up.



Thanks, Barry Smedley

[Deleted User]

Thank you for the info.



Barry Smedley

Geoff

The eight cylinder main bearings are actually inserts, but not the easily replaceable type as in the later engines. They are bronze-backed babbited bearings, and are held in place by a countersunk-head screw, therefore you have to take the crankshaft to replace them. Up until 1940 there were shims in between the cap and the block, but these were eliminated from thereon. Barry, as regards the rattle, I wonder how he knows it is a main bearing? Normally a loose main shows up under load. A loose piston would be more likely, but one would have to listen to it to ascertain with any certainty.

Geoff.

Park_W

Barry, to amplify a little more: the way one "renews" these 8-cyl. engine mains is by sending the old bearing inserts to one of the folks who does rebabbitting. They do them to what Hudson called a "semi-finished" condition ... that is, they're not bored out to the exact size of the crank's main journals. After having the crankshaft journals machined, or at least checked for exact journal diameter, the machine shop then installs all five semi-finished inserts and "line bores" the babbit lining to the exact size needed for a proper fit to the crank journals. Line boring ensures that all five bearing holes are on the same axis, which corrects for any misalignment of the block's bearing "saddles" as the block has aged. This is usually the case, which means that if you just had the individual bearing inserts machined to size and installed them, the crank would lock up because of the misalignment of the bearings. Then the only thing you can do is put in shims to provide more bearing clearance so the crank will turn freely. But now you have the bearings running with substantially more clearance than desired, and they won't last long. So ... you pretty much have to have the rebabbitted inserts line bored to do it right. And when you talk to the machine shop, be sure they understand you're talking about line boring the babbitt bearing material, not the cast iron block "saddles" as is commonly done with modern engines. Not many shops can do this work any more, first because they don't have a boring bar long enough for a straight eight block, and second because they don't have the boring bar cutting tool for the soft babbitt material. Other than the foregoing, renewing these 8-cyl. mains is no problem !! LOL.

SamJ

Even GPS wouldn't help me...:D

SamJ

Park W wrote:

Not many shops can do this work any more, first because they don't have a boring bar long enough for a straight eight block, and second because they don't have the boring bar cutting tool for the soft babbitt material. Other than the foregoing, renewing these 8-cyl. mains is no problem !! LOL.

No bar can be boring as long as they're serving cold ones...:eek:

Park_W

Having just returned from a week in Munich, I can attest to that, Sam!

Uncle Josh

Hey, the old 36 Terraplane rattles for about 15 sec. until the oil runs down into the bearings. I suspect the mains as the rods should get oil on the first turn. For the mains, and cam, we gotta splash enough oil so it collects in the trough on the inside of the block, and runs down into the bearings.