Packard Forum Index » V-8 (1955-56)

H.

One thought. Press needle bearings in pin holes in piston. Then use smaller pin.

So you mean drop the center of pin bushing in rod down 80 thou..i would be willing to try it...but jack would know if that would fly.

No experience with this but I'd think needle bearings and a smaller wrist pin would be a very poor construction. First of all, the forces would be acting on very much reduced bearing area probably resulting in extremely fast wear of the pin bore in the piston, and secondly that the pin will only be working a small part of a revolution I expect the pins will flat-side in very short order.

Jack- I do get very good pricing as an egge re-seller.

PackV8- I have a 374 going together now, I will get Rod dims and post.

Needle bearings are for low load applications, ball bearings and bushings are for heavier loading. Not only will needle bearings get flat spots, the cages may crack from the constant shock loading.

In Packards, caged needle bearings are used in king pins, lower outer pins, clutch linkage and similar applications. Uncaged needle bearings were used on cam followers and often wore out prematurely

Quote:The original question was the retail difference between cast and forged pistons.

Quote:
I have all the rod dimensions on file, as we rebuild them on every engine. What dimensions do you need?

jack vines

Troy T. Lookig forward to your measurements.

If convenient, also measure the amount of clearence betwen a stock rod/piston assembly and bottom of cylinder wall at the rods closest travel to the cylinder wall. Which should be when the piston is 1/2 way between TDC and BDC.

Edit: IIRC it is 1/16" clearence.

Edit #2: Not when piston is 1/2 way to TDC but when the centre of wrist pin is half way from bottom of cylinder.
Just spin one and see.

Motorcycle s use needle bearing for both pin and crank.

But my thought was to reduce Machining. Pressing in bronze then boring and reaming. Think pac pin is .908.. So to get 080 a 3/4 ..75. Or .800 pin.

Riki- close, the pin is .980 x 3.255

Thanks troy.

I knew an 8 was in there somewhere..

FWIW, a customer had a numbers-matching 374" block which wouldn't clean at .060". I gave him the options of sleeving the block or having custom forged pistons made up. Either was going to be about $1000.

He was going to teach me a thing or two; so he looked through catalogs for something close to an interchange and came up with Chevrolet 427" tall deck truck pistons and rings for $450. I said, "OK, we'll do it your way. Bore .125" over and hope there are no rust pits inside the water passages, cut .100" off the tops of the Chev pistons, cut retaining clip grooves in the piston pin bores, hone the bushings to size, rebalance the crankshaft. All the machining, plus pistons and rings will be $1200."

We bought the Chev pistons and rings so we could hone to their diameter. Fortunately, we hadn't done the machine work on them, because a rust pit hole opened up in a rear cylinder before we got to .125". We sleeved his block back to .030" and used Egge pistons.

For future reference, should 374" pistons never become available again, it's relatively easy to sleeve a 374" block down to use 352" pistons. As I said, whether to sleeve or use forged pistons is about a wash.

jack vines