# "Tightening up" a Stuart Beam



## smfr (Nov 3, 2011)

I picked up a Stuart Beam on eBay a couple of years back. The machinist didn't do a great job with tolerances, and everything was loose, so it knocked something awful when running.

Luckily there isn't too much play in the main gunmetal bearings. I'm thinking I can just file down the halves a little to reduce the play, and maybe re-ream them.

I've re-made the Watt linkage components, made a bronze bushing for the crank end of the connecting rod, and I'm in the process of making bronze bushings where the con rod and the linkage connects with the beam. What I'm not sure about is how to add bushings for the top end of the connecting rod; there isn't much room there to fit bushings (unless I make their walls 1/32 or thinner).

Other than just making new components, does anyone have any suggestions about how to tighten up a loose engine?


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## Jasonb (Nov 3, 2011)

The Stuart beam does have a tendancy to knock, look at the main bearing pivot.

Same subject came up on SmokStak a while back

http://www.smokstak.com/forum/showthread.php?t=91178

Re the top of the conrod, just open it out 1/64th or the next number drill up and turn a pin to suit.

J


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## tel (Nov 3, 2011)

Just don't get too carried away with the 'tightening' - they like a little bit of pre-wear.


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## Blogwitch (Nov 3, 2011)

For getting things a little tighter, K&S brass tubing can be used to very good effect for making thin bearing shells. Just open up the hole slightly to the OD of the tube, cut a piece of tubing off and loctite it in the hole. Dress to length when set.

Use a Dremel with a cutoff saw in it, otherwise you will find that because the tubing is so thin, it will distort.

John


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## smfr (Nov 3, 2011)

Jasonb  said:
			
		

> The Stuart beam does have a tendancy to knock, look at the main bearing pivot.
> 
> Same subject came up on SmokStak a while back
> http://www.smokstak.com/forum/showthread.php?t=91178
> ...



Yeah, mine sounds about like that ;D

I did find that the big end of the con rod was worn into an oval, so I think most of the noise was at the crank end. I have a nice bronze bushing in there now, and a newly machined crank pin.

I did try turning pins to a slightly larger size to fit larger holes, but didn't have good luck getting a nice constant diameter over the inch or so length on a 3/16 in diameter part, even after making and using a follower rest, playing with tailstock alignment etc. So I ended up using drill rod of the correct size to make new pins, with bushings. Now that I have a bit more lathe experience I can try again.


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