Irvine 61 Problem

[Ashley Hunt]

I’m hoping that someone out there can help me with a problem that I have with an old Irvine 61 engine. It hadn’t been run for about 15 years so I stripped it all down, cleaned and inspected everything. All seemed fine so having put it all back together again I tried giving it a run. What I’m finding is that when I try and draw fuel through from the tank by putting my finger over the carburettor air inlet and flicking the prop it appears to pressurise the tank and pushes fuel back up the pipe to silencer. Very frustrating and messy.

Any ideas anyone ?

[Martin Harris - Moderator]

Is the cylinder liner located correctly? All I can think of (at this hour and without an Irvine 61 to think about it properly) is that the piston port timing is out and it's pressurising the crankcase instead of the cylinder.

[cymaz]

Double check that the pipe work is correct and not moved when installing the bung

[SIMON CRAGG]

Sounds like a plumbing problem. Easy to get things the wrong way round, especially if fitting the tank when the model is inverted. I would check everything again to rule it out. Worse case, the liner moved round when you put it back together,

[Ashley Hunt]

Thanks for the suggestions. I’m fairly certain that the plumbing is correct so it can only be that the cylinder liner has rotated slightly.

Thanks again.

[Engine Doctor]

Hi Have you run the engine in the past? Is it a red crankcase or the silver three piece crankcase ?. If cylinder is in correctly and it still pressurises the tank then it could have a reverse rotation crank fitted .They were often fitted on the early engines whit three piece crankcases  for use in twins or for a pusher installation or when the engine was fitted to a reduction gearbox for using larger props. I believe the crank had a "R" stamped on the web. Could possibly be a reverse crank on the red version but not sure if they were available .

Edited By Engine Doctor on 29/05/2019 10:50:29

[Ashley Hunt]

I have run the engine loads in the past so it’s not a reverse rotation crank but that was an inspired suggestion. Thanks.

[Frank Skilbeck]

What happens if you block the silencer exhaust when flicking it over, that should pressure the tank and force fuel to the carb, providing the plumbing is all correct.

BTW my 53 recently became difficult to tune and would cut in flight, I found some "fluff" had manged to get into the carb limiting fuel flow and making the needle insensitive, the fluff was caught in the annular space just after the carb fuel pipe nipple.

Edited By Frank Skilbeck on 29/05/2019 12:17:55

[Nigel R]

I'm probably being stupid, but is the needle valve open enough?