plywood
Recovered N/A
Yep, I read that whole post.
Ok, well I've been up on a roof all week tearing off and fixing rotten plywood on a 12/12 pitch roof this week, and of course it has to rain, no damage, just a pita.
Anyway, about the timing curve, assuming that there is not a marine application Injector Pump for the particular diesel engines put into a work boat, then the IP such as the ones in our trucks have a mechanically operated cam that is based on throttle position. As the throttle is increased, the IP retards the timing to allow for load. At the same time, as rpms increase, the IP housing pressure increases, and advances the timing. These two functions work simultaneously, sort of with, or against each other.
On older gas engines in vehicles, you would have the same situation, except you had centrifical advance, in the distributor, with a vacuum retard to account for load, but in the Inboard/Outboard boats with the same old 350 chevys and 4 cyl Iron Dukes, there was only a centrifical advance, but no port for vacuum retard. The 2 stroke outboards had a mechanically operated advance relative to throttle position, with no correction for load either.
With smaller boats with small fast spinning props this works well enough cause there is more prop slip under load that just lets the engine spin somewhat til the boat catches up if someone guns it so to speak. But with a work boat and a very large diameter prop that really bites, if you load that boat it will really load the engine more if full throttle is applied, in which case it would seem benificial to have the retard function for the timing curve.
I parted out a turbo 7.3l block recently that had a couple bad rod bearings, could be that it was run without oil, but later I noticed that either someone messed with the retard cam on the IP, or it maybe wasn't tightened well enough when rebuilt and slipped. In any case I've been wondering since it slipped in such direction that there was no retard to the timing curve for the first 1/4 throttle or so. I had the IP on another truck before I figured it out, drove it around the block, and it smoked black under a small amount of throttle.
For me the subject comes up because I like to run a 2 stroke outboard on my say 19ft ocean fishing boat. What I have now is a 115hp. They did make an "Ocean" version of the 115 and 150 that have a larger diameter prop and higher reduction gear lower unit, which is great for powering over swells coming in over outgoing tide and such, but it concerned me to put even more load in the midrange or an engine that has no correction to timing for load.
I grew up around the ports of the North Oregon Coast, and the Commercial fishing vessels with diesels went and went and went as long as they were ran all the time. That's one thing about the hot exhaust, the cold exhaust usually means you have a plenum between the exhaust valve and nice salty water to condense in your engine.
