51 Commodore 8

[Deleted User]

If I have to shim these bearings. What should I use. I remember Geoff from N Z said to use cooking foil to check them. Would that work shimming the bearings. I'm talking about aluminum foil. This may be a dumb question but I don't se why it would work. Does anybody know?

[Deleted User]

I have another dumb question. I talked to an expert about using plastigage and he said it would'nt be accurate. Does anyone have an opinion on this? On using aluminum foil to shim with, I would probably be better off trying to find some shim stock if anybody around here has it.

mars55

McMaster-Carr has shim stock. Here is the link to McMaster-Carr. Enter "Shim" into the search box on left and click arrow.



http://www.mcmaster.com/



I think aluminum foil would be too soft to shim with. It would squeeze out under pressure. By the way, Hudson did not recommand shiming late model Eights.

Geoff

mars55 wrote:

McMaster-Carr has shim stock. Here is the link to McMaster-Carr. Enter "Shim" into the search box on left and click arrow.



http://www.mcmaster.com/



I think aluminum foil would be too soft to shim with. It would squeeze out under pressure. By the way, Hudson did not recommand shiming late model Eights.

I realise Hudson did not recommend shimming, but hey, if it works, why not? It all depends on the condition of the bearings really. All you are doing is laying shim in between the bearing cap and shell, to reduce the clearance. I agree that plastigauge is not accurate, as it is only a static test - move the crank at all and the plastigauge is destroyed. By using a thin strip of folded foil you can turn the crank and gauge the amount of resistance to turning. And yes, you can use foil in between the shell and cap - it will not go anywhere. In fact it can be beneficial, as you can lay it in half a thousands of an inch at a time, and reduce the length of each layer so that they overlap. this way you can for instance put an entire layer right around the bearing half, then the next layer a little shorter, and then shorter again, etc so you have a graduated reduction of clearance, as the most wear will be at the bottom of the bearing. I rebuilt the engine in my Essex 25 years ago, and I dug out the best main bearings shells I could find, mounted them in the block, and instructed the reconditioners to grind the shaft to the size of the bearings. They rang later to say that the rear main journal was .010" under the bearing size. I told them to leave it. When I got the block home, I inserted a .005" steel shim around both halves of the bearing shell, thus reducing the internal size by .010", and it is still in there, after over 85,000 miles, still not knocking!

Geoff.

[Deleted User]

Thanks Geoff for your advice again. I finally found a place that had shim stock. I did'nt think it would be that hard to find, the parts stores did'nt even carry it. I just got .001" thick because I have no idea how much wear these used bearing I got have if any. The tolorance is so close on these bearings, I figured I better not get any thicker because I can always use more than one piece and so on. I just hope my crankshaft is not out of round. It is not skored at all so I'm thinking it probably is not. On the rod bearings I am going to sand the caps till the tolerance is correct although I did'nt hear any rod knocks. I know most car companies don't recommend that either but I have done it before and got by ok. Thanks, Buck McGill

P.S. By the way, I am B Smedley's brother in law.

Unknown

You mean that guy that lives up on Sasquatch Knob ??

[Deleted User]

For added support to the shim recommendation. Bernie Siegfried, former Hudson engineer and engine man swore by the use of shims. He had a technical session which was regularly given to explain how and when to shim the bearings in Hudson engines... Spashers and the venerable insert bearing later sixes.

[Deleted User]

That's probably him. The one with the 53 Jet.