Fresh motor pix ready for paint

Suggestions, concerns, and what is the correct power plant for your Thompson.

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2qwk4u442
Posts: 24
Joined: Mon Dec 24, 2007 9:37 am
Location: North Eastern Ohio

Fresh motor pix ready for paint

Post by 2qwk4u442 »

Here are a few pixs of the first powerhead (minus the head), almost ready for paint. Rob

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thegammas
Posts: 566
Joined: Sat Nov 25, 2006 2:10 pm
Location: Wilmington, Delaware. peterstransky@verizon.net - put wooden boat in the subject

Post by thegammas »

looks fantastic!
Peter Stransky
1962 Cortland Custom Sea Lancer
Wilmington, Delaware
georgeb
Posts: 10
Joined: Sun Nov 11, 2007 5:20 am
Location: North Carolina

Post by georgeb »

Wow!
Image
George Barber
1961 Off-Shore
Montreat, NC
calvin
Posts: 57
Joined: Mon Sep 24, 2007 4:09 pm
Location: maryland

Post by calvin »

Great looking powerhead...did you bore each motor or just hone?
2qwk4u442
Posts: 24
Joined: Mon Dec 24, 2007 9:37 am
Location: North Eastern Ohio

Post by 2qwk4u442 »

Hi Calvin,
The blocks were first degreased as best possible, then bead blasted with care. All machined surfaces were taped off to resist the blasting, I didn’t worry too much about the bores. I weighed both blocks just for shi*s and giggles to see how close they were.

I inspected them for any problems, and thoroughly deburred the blocks inside and out.
The blocks and bores were in good condition and I suppose they could have been done with a very light hone and new rings, but I tend to be a perfectionist.

I Hand picked four +.020 oversize pistons determined by condition, roundness and optimal size. I cherry-picked these from 15 pistons @ +.020.

On a vertical CNC machining center I set up the blocks in prep for boring, checking squareness to the crankcase mating surface, checking straightness of the bores, out-of round and the center to center distance of the bores compared to the crank CL to CL of the crank throws. I didnt rely on the spec's, but rather the true numbers off each crankshaft. I also confirmed the squareness of the bores and my set-up to the head mating surface.

I then bored them to within .002 of finished diameter using a bore gauge, keeping in mind the piston sizes I had handpicked and the factory spec on clearance.

Then using a Sunnen Engine Hone at work to take to finish size, and with the guidance of an "old timer", we put the optimal crosshatch and finish to the bores.
I then thoroughly scrubbed and cleaned the block and bores in several steps.

I oiled the bores properly then sealed in plastic and boxed them, then put in a clean & dry warm area until ready for use. (it took me about 3 years to get to that step)
Otherwise, I pulled them out for inspiration every once in a while, and to admire them.
(I know, Im nuts)

Rob
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