I have been running two impulse mags for a while. If the impulse mag. goes down in the field, I am not interested in hand propping a 0-540. So if the spring in one breaks or a condenser goes bad you still can start easily. The other problem is people getting confused which mag is the impulse magneto and sit wearing a starter out trying to get the #@&%# thing to fire up. (yep that was me on a buddies boat after he rewired the control panel and crossed the p-lead wires.)
I changed out the standard aircraft starter for a high torque starter. The starter is a high torque, high rpm starter (I think for a toyota), it fits a coarse tooth flywheel gear, spins the motor faster than a standard lycoming starter at about 1/3 the weight, and is cheaper to rebuild. You can get the cheap one at CarQuest, and probably Autozone, I have the part number for one of those places if anyone is interested.
Just be careful if you are running with your timing advance a couple degrees to get more power. You can get alittle more power and RPMs, but you get more heat as well. If you get a kickback, the cheap starter's mounts are very likely to break. :wink: Trust me on that
You can get the conversion plate at most airboat companies in Florida and I know Mark's carries them. He also carries a high torque starter with a much stronger mounting bracket. With those two changes I have not had problems with that palm beach hull or neither have any of the other 2 lycomings are running around with. Just something to think about.
The angle valve 0-540 temperature on the palm beach hull I run sits at about 120-130 at cruise (1700 to 2000 RPMs) and gets up around 160-180 if we are running in the 2400 - 2600 RPMs. I have seen shrouds on 0-540 on airboats to get the temperature up to recommended aircraft operating temperatures.
There is a good Yahoo Lycoming discussion group for airplanes that all sort of topics appear. Mahlon Russell with one of the major aircraft overhaul shops fields the questions. I think he was a mechanic with Lycoming for years and is now in charge of customer service or something at Mattituck Aviation I believe. Here is the site.
lycoming@yahoogroups.com