123Cat

I was having a good run with 11 flights lightly tightened with a paper gasket ,


I didnt have a proper tool to do it up tight and it came loose , gives me a chance to do so more work on it


I dont mind if I disturb the fit and make it looser , its too tight over the top anyway

The piston is sealing half way down from the top , its not a great piston

but starts OK when its hot , terrible when its cold

The 2.5 mm piston pin is still OK

here is a picture

nitroairplane

Funny I had a PAW 09 dismantle itself while running yesterday.

123Cat

It came loose in flight and there was black goo on the model where the engine was chewing its self , but it was only loose about an eighth of a turn as the muffler ring fouled on the tank

Do you use paper gaskets between the parts ?,

I use A4 paper to make the gaskets for the cyl and backplate

I need to make a tool to tighten it as you cant get a hold of the cylinder

greggles47

Hi Cat,

Guessing it's the Silver Swallow? but regardless, I use brown envelopes as gasket material.
For the screw-in cylinder, use a drop or two of thread seal and tighten with a length of leather belt. If you hold it with a pair of pliers, it won't slip and give a nice tight fit. Use the belt on the cylinder muff (cooling fins) as well and it tightens and loosens without marking the ali.

Regards

G

123Cat

I used multigrips with copper shim on the cooling fins and a vice and soft jaws to do the cyl

And a 12 inch rule to do the Backplate

AMB

When I installed the ring muffler used the factory gasket a thin coat of copper-coat gasket on all surfaces, a piece of leather belt over cylinder, then tight with pliers no leaks and never a loose thing this is the procedure I used on all my PAWS and a couple of Sharmas with the PAW rings, the sharmas had to have the back of the lowest fin dremeled off for clearance martin

Recycled Flyer

This advice I got from a well respected Team Race engine builder -
heat the crankcase (not the liner) with a heat gun before assembly.

That way the outer thread bites down that bit harder when it has cooled.

Oh, and use copper or brass ring between the cylinder liner and the crankcase as paper or card has too much give in it and will eventually loosen up giving you the same result again.

AMB

Recyled flyer never had any issue with factory PAW gaskets they are 1` think fiber , also rubbed oil in befor using to prevent any rips then th coppercoat stuff martin

Recycled Flyer

Martin, if you had a choice between fibre and copper or brass with screw in liners, which would you pick?

We are talking liners here, aren't we?

qazimoto

My Feedback: (1)

I use this one made out of an old thick leather belt.

Seems to work best when the engine is hot and it may take a few separate goes to get it right.

It doesn't pay to get it too tight, you may need to get it off sometime.

Ray

nitroairplane

The PAW cylinde uses 3 screws to hold it down.

123Cat

I was thinking lap the surfaces ,

but that is the old lapping paste thru the engine wear it out stuff


Ive been doing

so a copper gasket how thick?? and do you anneal it first

qazimoto

My Feedback: (1)

There's no real need to put a gasket between the liner and the case in a PAW engine and this would effect the exhaust duration. AFAIK the PAW 55 is the only one with a screw on cylinder fin jacket.

Ray

Recycled Flyer

Thick enough so that when the cylinder is fully tightened down the rotation of it is such that the wrist pin holes do not form a bridge between the transfer ports and the exhaust ports.

If they do then you will lose some charge straight out of the exhaust.

In other words there is no set thickness for the gasket but simply enough of it to coincide with the final rotational alignment of the cylinder. Simply sand down the metal ring until satisfied.
Try being that accurate with card or paper!

The rest of it some one else will have to chime in as its all that Iknow about these kinds of engines but I suspect that annealing will make little difference.

P.S. If it has a fully floating wrist pin then catching it in a transfer port is an issue too if the wrong rotation of the liner is chosen!

steve111

Also the 049 and 06.

123Cat

What about Alfoil between the surfaces

Recycled Flyer

How much rotational torque do you think that 0.2mm of aluminium foil is going to take before it shears?

And how many layers do you propose to use before you achieve the correct rotational position?

AMB

Al Foil might be ok if heavy enough like a broiler pan thickness or pie pan, have used it for head gaskets martin

123Cat

Thank you

I got it together

I cant actually tell you the method as that is only privy to the Silver Swallow works team and other Silver Swallow users

That and certain other trick modifications I will post up as a picture

123Cat

Well , I cant tell a lie , I tried to geta hold of the works team , no luck

, I even Emailed CS Engines but they didnt answer , so they must be on holidays

I used A4 paper and did it up tighter and A4 paper for the backplate

Im thinking Alfoil would make a good gasket as you can cut it with a scalpel, but its awfully thin at half a thou

123Cat

Ive got a piece of 1mm stainless on the backplate to try and stop the conrod from eating it

qazimoto

My Feedback: (1)

Paper is fine, that's what I use all the time. Also a gasket needs a certain amount of compressibility to work properly so anything used needs to be relatively soft. If you try Copper or Brass it would certainly need annealing.

Some of the people pontificating about gaskets above have probably never made one in their whole life.

A trick shown to be decades ago when we were using Series 13 Taipan diesels in c/l Junior Ratrace, was to discard the gasket and coat mating surfaces with Auto Joining Compound. "Rolls Royce Joining Compound" was the stuff I had access too. You waited till both surfaces had cured and then assembled the parts.

It was very effective and again required no gasket.

qazimoto

My Feedback: (1)

My two PAW 80's (049's) have three screws holding the cylinder fins on.

Ray

fiery

My Feedback: (2)

Ray

"Rolls Royce joining compound"

Was that blue Hylomar?

http://www.hylomar.com/index.php?opt...d=62&Itemid=70

qazimoto

My Feedback: (1)

No the stuff I've used had a dark honey colour.

I first used the RR Joining compound (aka Gasket Goo) as a young apprentice in the early '60s, and always used similar
generic products for assembling bits of car engines. eg rocker gaskets. I bought some fresh stuff from
Repco just a few years ago. It came in a little bottle with a brush in the lid.

I don't know about Blue Hylomer but it could be an updated equivalent.

One of the advantages of using this stuff to replace gaskets in model diesels is that it effectively pushes the piston up the liner just a tad equal to the difference in mating surface thicknesses. Hence it can restore hot hand starting in a tapered bore engine when it begins to fade.

It does also alter the exhaust duration of the engine, and this has to be balanced against any starting improvement.

Greg Ardill has my third best Taipan series 13 in his "Burford" Vintage A Voodoo team racer, and has won the StIves Burford Day Vintage race three times with it.

It has this mod!

Ray