Alright. I recently bought a second hand plane and the engine which was installed i quite literally a mongrel. It has an os 60 fsr h (helicopter apparently) an os 72 replaced with a 7b carby but yet to bet a screw for it and the gold aircraft head. Will these things affect it much? Also if it would not work how much would all the parts be individually?

If the engine runs OK, then go for it. The head won't affect it all that much. Worst case is the engine might tend to run too cool which could affect its performance on colder days, but in the summer when it is hot and humid, it won't have as much power loss from heat sag. But folks have run the heli engines on model airplanes already many times. The heli-carbs tend to be wrong for airplanes, which is why they swap out the carb for a airplane carb.

If the engine doesn't work, your best bet would be to get another engine instead of trying to fix it.

Is the 7b carb an airplane one? I seem to remember seeing them on an ad for an airplane engine at some point. The problem i think it was the 72 carb had now low end needle valve instead it had different pins that you put in and i didnt have any of the others and the low end was too rich

if the barrel slides in and out laterally then it would probably be unsuitable for airplane use. if its the regular rotating barrel type it should be okay depending on whether it rotates in the correct direction.

The 7b carby twists and moves in and out at the same time (e.g. The more i rotate the barrel the more it moves out, if i close the throttle the barrel rotates back in a bit)

Originally Posted by scrubmonkey

The 7b carby twists and moves in and out at the same time (e.g. The more i rotate the barrel the more it moves out, if i close the throttle the barrel rotates back in a bit)

That should not present any problem. Many airplane carbs move sidways as they rotate. Just fire the engine and see how it runs - like Earl suggested.

I need to get an idle stop screw for it as it was missing it when i got the carby. Next time im at the lhs ill check out the spares for one

Unless the idle stop screw affects the carb such as it lets the barrel come out, then you do not really need it. The idle speed can be controlled from the servo and end stop adjustment via the TX. So you may be able to run the engine without the little screw. The screw is a small metric screw and you might have one in your parts bin too. Some screws have a smaller tip filed into them too. But it is hard to say which one your carb has until you try one to see how it fits and works.

Yes the 7b carby the barrel rolls out and in with the rotation so it really needs it. Am going down to the lhs soon to pick up a new needle for an os 46 max fx as it keeps sucking air in from around it and none of the shops ive looked in have a small enough o-ring

Try a watch repair shop. They usually have a assortment of small O-rings for repairing wrist watches, etc.

The 7B carb came on the old OS60FSR. It needs the idle stop or the barrel will fall out.

Ive noticed that. Im waiting till my parents can get me down to the lhs to get a spare

You probably know,but the barrel moves away from the needle valve as it rotates,automatically adjusting the mixture,as it does that.