Stuart No 4 Engine

[spacy]

pm replied to

 

[f350ca]

Sorry, haven't posted for a while, been able to escape this project and do some other work.
Have most of the parts built with the exception of the main rod packing gland. Been making scale fasteners to replace the machine screws I used, many more to go.

Greg

 

[LorenOtto]

Looking good!

 

[bobden72]

Maybe a bit of house keeping is required

 

[f350ca]

Thanks,
Actually just cleaned up the bench, you can actually see some of the surface. lol

Greg

 

[f350ca]

Wanted to add a control valve, did a search on the internet and the great goddess google linked me back to here. Blogwitch in answer to another query posted a set of plans for a globe valve. Had to change a few sizes to match my piping but all worked out, THANKS a bunch John

It looks good but may make one slightly larger. The engine runs nice on 8 psi but with the valve in line I need about 20 psi on the regulator to get enough flow. lol

Greg

 

[Jay Ladwig]

We think the engine for the boat was 5 inch bore, never did take the head off to measure.
Here's a link to the engine on a dry run.

Thought the crank was cast iron, wrong, was a low carbon cast steel, miserable to machine. Tried every grind in HSS I could think of and a couple of inserts, nothing gave a nice finish. In the end I rough cut it with a sharp pointed tool then file and emery close to size and lapped to final dia. In hind sight I should have cut one out of plate.

To machine the throw I made a jig that allowed one end to go inside and a grove to hold the throw with a light press fit.

Decided to open up the crank bearings on the mill with a drill and reamer. I fastened a block to scrap to the bed, drilled and reamed it to 3/8ths, then mounted the crank case with a dowel between a collet and the bored hole. This aligned the bore to machine. I then brought an angle plate up to it and clamped everything.

Have to remove a bit of the casting in the crank case, The throws don't clear at the bottom, Oops.

Had a 1 thou over reamer, and lapped the crank to 2 tenths under, so have 0.0012 clearance. It rotates but is that going to be enough clearance for oil.

Thanks for watching.
Greg

I have to say, one of the best things about being a machinist is learning from others. I built a Stuart #1 in 1977, when I was in trade school, and I wrecked the crank,,,tried to make offset clamps to run it between centers per my instructor..and then did it 2 more times from bar stock, before getting it right. What an awesome crank jig!

 

[Bob Sorenson]

This thing is eating up too much of my precious time, bloody thing is addictive.
The intake ports were cored in the cylinder but were too far apart at the valve end. Had to cut the openings closer to the exhaust port, but this meant that the valve wouldn't cover the end.

Cut a thin slice from a scrap of cast iron and ground it to .1 thick, then cut the ports with the correct spacing and size.

Sandwiches nicely behind the valve chest.

Made the connecting rod today. The drawings show the joint straight across the journal, decided to step the joint to locate the haves and not rely on the bolts.

Starting to look like an engine.

Know I could machine a full sized one faster. lol

Thanks for looking
Greg

I am building a #4 right now and have noticed a similar problem with the porting cores on the cylinder. They are too close together so the exhaust port will be way too narrow. I like your fix. I'll do that. I also saw in an old catalog that the #4 had a 4-1/2" flywheel. This kit came with a 5" (probably from a Stuart #9) and the bases are not tall enough. It will need a little plinth, or a small diameter flywheel. Great job on yours and thanks for showing this.

Take care, Bob

 

[Tug40]

F350, just saw this build log this morning.
Will make some great reading.
Thanks