OS 40 LA backplate gasket

[Jeffrey Cottrell 2]

Hi guys

Got an OS 40LA with a blown backplate gasket (plastic backplate).

Internet search suggests I can make a new one from, for instance, a glossy magazine cover. Can't imagine this being a high stress part, so what do you think?

Anyone suggest a better material?

Jeff

 

[Don Fry]

Buy a motorbike gasket, cut as needed.

But dirt cheap, try the advise. It might work or not, and I’m inclined to think, it might. But, caviate, not a proper engineering solution, and it might not last forever. 
Your shout, do you think the airframe will break first or the backplate seal. Having established a seal problem, you know the signs, if a new one is needed, it’s still zero cost, and re-evaluate. 

But I think, proper materials, buy a gasket. I’ve got one from a monster bike, and am still cutting off bits 20 years later.

Or if desperate, an OS part, but that is desperation, a seal is a seal.

[gangster]

Many years ago I spent a couple of hours trying to get an old k&b45 running. The head was blowing. Various gaskets I made did not work. I was out of tricks and stood there staring at it eating a Mr Kipling fruit pie. I looked at the foil tray it came in and was inspired the thick foil mad a wonderful head gasket

[Jeffrey Cottrell 2]

Hi Guys

Thanks for your thoughts, but I've found something else which puts the whole project in doubt.

So first of all had the engine running on the bench. Seemed to be pretty sweet, although running rich and didn't seem to want to lean out.

Probably just the carb wanting a good clean.

Only reason I noticed the gasket was the amount of unburnt fuel collecting round the back of the engine, which led me to the backplate screw missing and from there to the gasket.

However, checking the rest of the motor out, I find a crack in the big end of the conrod. Bush itself looks in good nick but has left me wondering what else I'm liable to find.

Found a new conrod on e-bay, not too pricey, but means the motor not such a bargain as I hoped. If I find anything else, then costs could spiral. So, opinions please.

Soldier on or cut my losses?

Thanks

Jeff

[Don Fry]

That motor has all the signs, it’s a nail. Get something else. 

[Paul De Tourtoulon]

Make a new con-rod out of a lump of duralumin.

 

A gasket from a document folder.

Edited October 31, 2021 by Paul De Tourtoulon
gasket

[Nigel R]

Cut and run. La40 easy to find second hand. Sell your nail for spares and repairs.

[Nigel Grant 1]

I think the others guys advice would be best regarding moving on. After all, when you get to the field and weathers good you want to be able to fly. But if you decide to give this one a chance, attached is an article I found on the net ages ago about setting up LA 15's for some type of combat flying in the US. If the file attaches and can be opened, you will see on page two that for the author of the article, it is standard to replace the gasket straight away on a new engine with some type of automotive liquid gasket material from a tube. Good be a way forward, especially if the stuff's not too dear. 

LA-15 Clunk Tank Secrets.pdf

[Rich Griff]

Get an exploded parts view so you know what's involved with stripping the engine.

 

Clean and examine. Anything else a problem ? Access and go from there.

 

You have a good Conrod ?

 

DO NOT allow any sealer to enter a threaded hole else the hole WILL split !

 

Even a thick envelope can provide gasket paper, thin card, cereal packet, a glazed paper, mmmmm not really unless your in the Sahara and have nothing else.

 

Nice idea about Mr Kipling foil...dare I say an exceedingly good one !

 

Bet you didn't expect that comment yeh !?

[Rich Griff]

Gosh, did he use enough red sealer there ?

[Jeffrey Cottrell 2]

Hi Rich

Thanks for the ideas, maybe not so much for that awful pun!

However, you're a little behind the times.

Since I have already found a cracked conrod, perhaps I have already stripped the engine down? Who needs an exploded diagram for an LA?

Also, I don't have a new conrod, only seen one for sale.

Final nail in the coffin is this.

Spotted what looked like a spot of rust on the bore. Closer examination, it is the brass liner showing through the chrome.

So, no doubt, this one's a write off. C'est la vie.

Got a FP coming off e-bay. Would I be correct in assuming I can transfer the remote needle set up from the LA to this?

Quite like the idea of keeping my pinkies as far as possible from the whizzy bits plus it would mean the LA is not a total loss.

Straw clutching at its best, eh?

Jeff

[Engine Doctor]

You should be able to  simply swap the rear NV if its the metal braket type. Just leave the stadard FP NV wide open or fit a blanking plug to the FP carb where the NV screws in . 

[Jeffrey Cottrell 2]

Hi ED

Don't know if the spigots are the same size, but if so I can transfer the carb as well as the needle.

Will know more when the new one arrives

Jeff

[Nigel R]

FP, fabulous motors, better than the later LA I think. 

[Jeffrey Cottrell 2]

Hi Nigel

Yes I'd heard they were more powerful than the LA's. If I can fit the remote needle, would have the best of both worlds.

Mind you, there's a snag (isn't there always?)

Just heard from the seller. Apparently e-bay have given him an address that is two years out of date and was deleted years ago.

So apparently my motor is headed for somewhere 100 miles away.

Ho hum

Jeff

[Engine Doctor]

17 hours ago, Jeffrey Cottrell 2 said:

Hi ED

Don't know if the spigots are the same size, but if so I can transfer the carb as well as the needle.

Will know more when the new one arrives

Jeff

Hi Jeff not sure about carb spigot size but still doable. Re the address contact the post office or courier . They should be able to sort it.

Edited November 1, 2021 by Engine Doctor

[Jeffrey Cottrell 2]

Hi ED, thanks

Using the rear needle would be handy but not critical. As I said in my last post, current concern is to try to get the motor delivered to me here.

Apparently it's being delivered by Hermes, and only the sender can change the address.

Had a long conversation with him yesterday, but that cut short when he had to go to work. Waiting to hear back from him now.

Fingers crossed

Jeff

[Engine Doctor]

14 hours ago, Nigel R said:

FP, fabulous motors, better than the later LA I think. 

Yes far better quality from an era before accountants were in charge. I can't understand how the likes of ASP, SC etc could make engines that never shed the chrome off of the liner yet OS seem to make it a feature of their engines !

[Nigel R]

ASP probably tipped the industrial waste from the chroming process straight into the nearest river, OS would have needed to be a bit more responsible which must have driven the cost / difficulty up for them.

 

I always thought a ringed setup was best... But I understand why ABC was a good advertising ploy... "no running in"

[Rich Griff]

Yep, some times parts exploded views can be exceedingly usefull, especially for the tyro or those who are not sure.

 

It's good to know sometimes that the prop driver for example is held on via taper and collet, sometimes even a d type drive is not obviously, but point taken.

 

It's best to check...

 

Pity about the chrome coming off...

 

[Jeffrey Cottrell 2]

Hi Guys

is it paranoia if they're really out to get you?

So, bought the 40LA. Turned out to be an expensive paperweight, c'est la vie. Back to e-bay bought a 40FP instead.

Seller managed to despatch it to the wrong address, one I moved out of 2 1/2 years ago.

Lots more on e-bay, but having no luck actually getting one so far.

Can anyone confirm whether the LA carb will fit an FP?

Looking at one with a broken spray bar. Worth a punt if the LA carb will fit.

Your thoughts?

Jeff

[Graeme White]

Will the 40fp not make its way to you eventually?

[Don Fry]

Broken spray bar, raises a couple of questions;

why

how.

Motors are tough little things. If broken, always a sign of abuse, tweedling. And the owner can’t be bothered, don’t know how, or it’s a bit of junk he’s picked up in a lucky bag and is passing on

ie, a nail unless proven otherwise. 
You can ascertain if the carbs will swap, part number of the FP, will have the same part number as the LA.

BUT DONT ASSUME ( making an ASS out of yoU and ME), a broken motor has one fault.

 

[Jeffrey Cottrell 2]

Hi Don

Sage advice as always, many thanks.

Motor also has broken fins on the head, so sure sign of an impact sometime during its life. Maybe one to miss out on.

Currently only one bid of £9.99. Might put a speculative bid on of, say, £12. See what happens.

Other than that, I'm not sure you're right about the carb. On the LA one the fuel inlet is plastic and either moulded or glued in place. Either way not removable, where the FP one is a threaded hole for the spraybar.

Not sure about the spigot size, but certainly won't have the same part number.

Good thought anyway, thanks.

Jeff

 

[Don Fry]

Why is a broken motor worth £12. Scrap, for parts, obsolete, ancient. 
Re did OS carry the same carbs to FP to LA, I always assumed they did. They did nice air bleed carbs on the first. I will only think, the LA carbs were a cut down version. The FP carb was an Al turning, into a clamped receiver, with a o ring seal at the top to seal.

Old memories. I run motors, I don’t repair them.
In fairness, FP engines, while nice, are at least 25 years old. Accept no worse/ better than replacement, or just cheaper.

Can I offer you an early Ford XR 2, plenty of miles, not even broken, but burns oil. Bargain, never to be repeated offer, usual oil emulsification issues, no warranty.………..name your money and double.

23 hours ago, Don Fry said:

 

 

Edited November 2, 2021 by Don Fry
This site says this is a 22 hour old post. It lies. I just posted it