Another version of how not to build a model engine

Gallery, Projects and General > Project Logs

<< < (15/41) > >>

sorveltaja:
I made a bevel to brass button, and copper gasket also, and re-lapped the valve seats. With M3 screws it's possible to apply more fastening force to the head cover, than with earlier M2 screws:

So it's about time to assemble rest of the engine.

sorveltaja:
At this stage, head cover is fastened, and spark plug in place. I flooded the engine a bit with wd-40, and gave it a spin, to find possible leaks.

The head cover seems to be ok, and valves seem to seal ok.

But there is a leak, where the cylinder and head meet:

I was tempted to put some loctite there, but instead I used 'high temperature instant gasket' paste, that vulcanizes at room temperature.
Head screws were opened just enough to get the stuff between the parts, and then tightened:

When the paste is cured, it's like a soft rubber, making it easy to remove the excess material with a sharp knife.

But anyways, if the gasket paste fails under pressure, I'll get back to that loctite-schema :ddb:.

sorveltaja:
During the acid running tests, there hasn't been leak problems so far.

Current setup:

To save my fingers, I used trusty Dremel with rubber wheel to spin the engine:

After some fiddling, the engine fired. Short high speed runs, no response for the carb's needle, just as it did before. Fuel was ethanol.

Next thing was to test with gasoline. At first, the engine had same running habit, that it had with ethanol. I kept on trying, but letting the engine to cool down between the tests.

At first time in its history, the engine started to show even faint response to carb needle :bugeye:.

Carburetor has 1.9mm throat, but with 1.5mm ptfe plug, it worked better.

So there is a new carby to be made...

sorveltaja:
I made a new carburetor, that differs from previous ones, so that it doesn't have the needle going across the throat. Parts are ready to be soft soldered together:

NickG:
S,

Nice work on that carb :scratch: I don't really understand it but it looks good! Just wondered - have you considered Jan Ridders petrol vapour carb? That could solve your mixture issues drawing in a pre-mixed vapour, just a thought. Even if you didn't want to pursue that route, or felt it was cheating or something at least it would give an indication as to where the problem lies.

Nick

Navigation

 Message Index

Go to full version