It seems like the changeover between the 2QM and the 2GM happened somewhere in the high 200s to about 300 range for hull numbers. If you have an early boat with a 2GM engine, my guess is that the engine was replaced at some time in its history.
Anyone looking into these boats should not think of model years, instead they think of hull numbers.
J/Boats and Tillotson Pearson made incremental changes to the boats at a certain hull numbers. Unfortunately, much of the ancient history of the J/30 is not recoverable. There was a fire at the TPI factory in the late 80s that destroyed most of their old records about things like this. So most of what we have to go on is reconstruction of events (like this discussion) and the memories of the Johnstones and our own long-term owners.
The main reason for the changeover seems to be the unavailability of the original engine. There is another reason, however. With a fresh water cooled engine, the thermostat is set higher (around 180 degrees IIRC) versus the raw water cooled temp of only about 140 (again IIRC). The higher temperature allows a hot water coil to be added to provide domestic hot water for pressure water systems. On the other hand, the cooler thermostat temp of a raw water cooling system is used to prevent salt from precipitating inside the engine. That's one of the reasons these engines have lasted so long.
On the issue of smoking at startup, I agree with a few caveats. The engine should start up relatively quickly if its in decent shape. The engine should not need to be turned over for a long time to build compression. But remember, this engine does not have glow plugs. Therefore if you're trying to start the engine when it's been sitting for several days in Canadian March weather, it may not start all too quickly. Also, the engine will run only as well as the fuel injectors will allow it to run. On Mondial, I know that I had a problem with both hard starting and smokiness that was due to clogged injectors. For a very nominal price, a mechanic cleaned the injectors and the engine would start up within a few seconds (again, at reasonable ambient temps).
[This message has been edited by jmruzzi (edited 03-26-2002).]
