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Alum bronze cam bearings riki's 56 400

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Just curious, why did you chose bronze over the babbitt-lined steel which at last check were readily available? Isn't the babbitt is a better bearing surface than bronze?

Hi, Dave,

with the oiling problems, (pump), cams bearings were and i think are a pressure source to check for clacking.

So going to see how the alum bronze wears.

I have new babbitt cam bearings from terrill ,,which were used to size these.

That's a "it depends" question. Babbit was one of the earlier bearing materials, just after greased wood, steam era. It's rise goes back to methods they had to manufacture bearings(casting), ease of tooling, methods of lubrication, and shaft speeds. The more modern babbit styles came after WW2 due to it's limitations in higher energy motors.
"It depends" on the coefficients of friction, coefficients of expansion, clearances, forces, lubrication, rotational speed, temperatures, vibrational dynamics, etc. to predict bearing life, not just the bearing surface.
Babbit's depend on tin and with tin, you get lead, antimony, and a few other elements which are no longer mentionable to environmentalists. They still use tin plating in diesel service for coating the pistons after hard chrome for lubricity.

Very interesting thinking, Riki and one modification I've never seen or even considered.

If restricting oil to the cam bearings is desired, it's easy to install the cam bearings with the oil holes out of line with the block. Then, new oil holes of the desired smaller diameter can be drilled to create a restriction.

FWIW, the cam bearings and journals are one of the few wear areas seldom a problem in the Packard V8s. Thus, restricting oil probably doesn't hurt anything and may raise pressure to mains.

In order of problems usually found in Packard V8s:

1. Main bearings - always going, often totally gone. I usually drill the main bearing holes and feed passages to 9/32". I've never been able to prove it helps main bearing wear, but a carefully machined and assembled build with good oil is going to last a long time anyway.

2. Rod big end bearings - wear but don't usually fail. When the mains start pounding, the rod journals usually also require a regrind.

3. Rod small end bushings - about average wear. I've seen one engine with oversized pins installed in the pistons. Now, I have to dial bore check all the rods just in case.

4. Rocker arms - high miles or severe neglect will show worn shafts, rocker ID, wear in tips.

5. Cam lobes/lifters - about average wear

6. Pistons - always cracked where the barrel turns to the flat if engine is run hard, as in Studebaker Golden Hawks with overdrive.

7. Valve spring retainers - Early soft retainers should never be reused in anything other than a trailer queen rebuild. They will fail eventually.

8. Cam bearings and journals - seldom to never a problem. So how will Riki be able to determine if bronze cam bearings are worth the effort? It would almost require a test of oil pressure with DuraBond bearings, then replacing them with custom bronze.

jack vines

Thanks, for the input, fish, and jack,

jack question, i forgot the holes at 3 and 9, do plugs go in there?, can't find in book, (parts) book,

Riki, if you're asking about the holes at the front of the oil galleries, they're covered by the cam retainer plate and spacer and the slots on the back of the plate feed oil to the cam chain and fuel pump eccentric.

Can't remember if we've confirmed you have the late design plate and spacer, but that's a must.

jack vines

thanks jack,

i have the late one, updated one, i just drew a blanks on that, been so long,