Irvine 25 Sleeve Nut

[Frank Skilbeck]

I'm looking to use an Irvine 25 Blackhead I have, barely used and in very good condition, but I've run into a problem, the propshaft is too short for a 0.5" thick prop hub, spinner plate, washer and nut. A sleeved nut may do the job, but the thread is 1/4" UNF and I can't find a supplier. Anybody got any suggestions?

[Keith Evans 3]

Tyr Just Engines and look for "Shaft Extensions " .

[Martin Harris - Moderator]

A friend with a lathe?

[Engine Doctor]

Hi some of the Irvine's around  that era (mk 1) had a stud insert for the threaded part of the crank. See if your engine has it. If it it does then simply buy a high tensile 1\4 unf bolt and cut to length. Mk 2&3 had one piece crank and should be plenty long enough. If the crank has been shortened or just too short then just engines should be able to help.

[Former Member]

[This posting has been removed]

[Frank Skilbeck]

Thanks all, I'll give JE a call.

I don't think it's a stud insert as it's not threaded along it's complete length.

[Keith Berriman]

This sounds like a an engine that may have been in a radio controlled car . When the shaft has to shortened down for the clutch assembly. A shop that sells IC car engines may have one

[Frank Skilbeck]

Posted by RC Plane Flyer on 01/04/2017 19:59:59:

This sounds like a an engine that may have been in a radio controlled car . When the shaft has to shortened down for the clutch assembly. A shop that sells IC car engines may have one

No it's my engine, had it from new, but only used it in one model some 25+ years ago and it's been oiled up in it's box every since, you can easily get a prop, washer and nut on, but a spinner back plate means there's no thread left. I have an OS25 FSR too (but the carb is bust) and it has a bit more thread. I don't know why Irvine made it this short.

The other option is to find a prop with a hub that's less the 1/2" thick, but the 9 x 5 and 9 x 6 props I've got, Graupner and Master, are both 1/2" thick.

[Denis Watkins]

You may not like this Frank, but I run three .25s, and all with your problem

I use spinners, but fitted with a half nut and precision thin washer, not the mild steel type, and everything fits and stays on

I do know why we use a full nut and a thick thrust washer, but the half nut set up has never parted by itself

Edited By Denis Watkins on 01/04/2017 21:05:56

[Nigel Grant 1]

I have experienced a similar situation when I picked up an NIB OS 25 SF which had a shorter shaft than the later model 25 FX's I was used to. I got by with using APC prop's and switched from Du bro spinners to aluminium backed Greatplanes ones. I have just measured a Master and an APC 9x6 and the APC is 1mm thinner at 11mm.

The thinner prop hub and spinner back plate gives enough thread in front of the prop washer to engage the nut without the risk of it stripping and when cinched down tight the shaft has filled the whole depth of the nut.

Nigel

[Former Member]

[This posting has been removed]

[Frank Skilbeck]

One ordered from Just Engines, thanks all.