ORIGINAL: Wildstyle
I still have to make a bracket to support the underside of the carb. the insulator is just a piece of actel sheet, 3mm thick.
Curious how the OS's will hold up. Especially the bottom main journal (plain?)
what do you mean by plain main journal? the bottom end of the OS120FS has a bronze bush, I think the later alphas series do not.
I've run the engine on glow and clocked up enough run time now to switch over to gas. Im running redline synthetic oil at 16:1. I know it may seem like alot but redline is very clean burning and in the grand sceme of things 16:1 is still alot lower than 16-18% glow mix.
I was thinking about installing a small nipple (such as a exhaust nipple) in the backplate to allow a small shoot of pure oil to be injected from time to time, to aid in bottom end lubication. there's two bosses in the back plate so drilling and tapping this area will be easy. Any thoughts?
I should mention my inspiration came from the work that ''pull up now'' has done and the videos ''i7x58'' has posted of his sweet running satios. not to mention w8ye and others in this thread and there trial and error examples. And not to mention the fact this is my last glow engine that I own, no more hydroscopic, rustly, slimely glow fuel
Wildside:
Thanks for the compliments about this thread, and the success we've had converting these engines.
A plain bearing is a bushing, either bronze, brass, oil impregnated bronze, or even babbit (tin & lead), that is contained within a diameter at the end of the rod. That circle on the end of the rod is called a journal. From your description, you have a plain bearing. The alternative would be a ball or needle bearing cage.
The nipple on the crankcase to inject oil is probably not necessary. I've inspected my conversions' lower ends a few times, and there is always plenty of oil. Besides, the upper end of the valve train is more of a concern. There are some who have devised a check valve system to route oil to the cam gear to address that problem. I've not had to resort to that though. Never let the engine lean out. Even if your carb comes loose from vibration, causing an air leak, is enough to destroy the engine if you don't catch it quickly and throttle back. Besides, the crankcase on a 4 stoke needs to breath freely. It's not like a 2 stroke that has a sealed crankcase, using the pressure pulses to drive the gas-rich charge into the cylinder up through the bypass ports.
The lack of a lower support on the carb is one of the instigators of the vibration that can loosen the carb, by the way.
What is actel? What are it's thermal properties, such as Tg (glass transition temperature). Do you have any gaskets between? Do you have any performance numbers from this engine, running, yet?