Dodgy steam engine...help!

[Corrado]

I recently bought a new twin marine engine & I've had nothing but trouble with it. Firstly it would not run, even at 50 psi. Then I found one of the eccentrics loose.It seemed to exhaust a lot of steam for no movement.
I re-tightened the eccentric & it finally started to turn over on it's own steam, but only slowly & still exhausting way too much steam.
After putting 4 boilers through it, it has freed up & spins freely but is very weak & still blows too much steam.
It is a 3/4" X 3/4" twin & I can stop it turning with one finger! Due to most of the steam being exhausted, it empties my 4" boiler in a minute. This can't be right?
I was told this engine could drive a small dinghy. What is wrong with this engine?

 

[Mechanicboy]

The timing is out of position. i readed at new again in your comments... The excenter can be i 20 degree from BDC while the crankpin is on top. Or only 90 degree excenter with crankpin at top. Which brand is the steam engine produced from?

Here is the better to explain about adjusting timing..

[ame="http://www.youtube.com/watch?v=YyIZQb-t9mc"]http://www.youtube.com/watch?v=YyIZQb-t9mc[/ame]

 

[don-tucker]

Could be one of the valves is not seated properly,maybe a gasket is fouling it or something stopping else stopping it seating,I just had that with a rob roy
Don

 

[Charles Lamont]

It is a 3/4" X 3/4" twin
I was told this engine could drive a small dinghy.

You were lied to.

Incorrect timing would not make it blow by.

How good a fit are the pistons? Do they have rings, soft packing, or labyrinth grooves? What is the condition of the valve and port faces?