Tuesday, March 31, 2009

Cleaning, Preparation, and Bearing Gaps

There isn't much to tell about my progress. I received another order of parts from Stewart Eng. I've cleaned the engine block and checked the new rings for clearance after honing. Everything checks out there.

The next step is the big one. I need to find a reliable machinist to turn down the journals on my crankshaft. I'll also be ordering a set of big end shells and a new rear bearing. I need to get a good idea of what undersize bearings to order.

Below is the measurements of the crank that I've taken.  It looks to be a 30 thou under on the big ends, and a 20 thou under on the rear main.



Anyone know, what measurements I should tell the machine shop?

I would think:

-0.030" bearing shells... grind the big ends area "A" to 1.5950" / 1.5945"

-0.020" rear main grind the rear shaft area "C" to 1.4795" / 1.4790"

But would it be more wise to hand the machine shop the rods, and bearing shells .. and ask for a gap.  What gap?  Would that be 1.0 thou or 1.5 thou gap?

Opinions?

1 comment:

  1. I just spoke with David at Stewart Engineering. My suppositions were correct and the measurements listed above are correct for -0.30" on the crank pins.

    I learned that the exchange on the rear main allows me to specify any dimension on the rear main. They will simply machine that out to whatever I need.

    Now I just need to get that plug out of the end of the crank and clean that out VERY well.

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