The boost port is similar in design to the "wart"...only with the HP and Webra, they are somewhat externally hidden by fins or "badging"
Check the K&B c/l speed (and r/c pylon ) engines designed by Bill Wisniewski for more info...

https://www.modelaircraft.org/files/WisniewskiBill.pdf

Hi. I have the same engine. On the side of the mount is the marking "C657" I see that yours says "C580" do you know what these markings mean?
I'm hoping it can give me a more accurate date of manufacture as the engine was my fathers and I'm looking to sell it.

Many thanks

Hi there,

Very, very old thread, I know... but...

Well, I have to messed up of HP 61 F's. Very mistreated by a dork. Maybe there is chance for a 9th life.
Two wrecks could make a working one.

Is there a parts listing to find? PDF-format. So I can reconstruct some details.

The sleeve is Schnürle ported, but old style machined, like a diked piston and sleeve.
Piston ring has no stopper key to slot and can rotate freely. The type of porting makes no need for it.
The ring is even grooved, so works like duoble seal.

The combustion chamber is a hemi type.
Bearings are stock type, easy to find.

Main question, how is the head shim/seal constructed?
On a technical drawing found in the reviews at Sceptre Flight, it looks like there are two in place.
1 to seal the sleeve,
2 a spacer to lock the separate cooling element.

The sleeve has no collar, as more common today's engines show.

Hope to rive this tread, most knowledge slips away on old age sadly.

And get a new leash of life for it...

Thanks in advance,
RCP

You might check the MECOA website. They bought up the stock of a lot of out of production engines.

I'll write them, but expect fairly high cost, has to be shipped at the EU...
Could be hell on earth :-)
It is just on the edge of binning it for scrap metal...
A complete example might be more clever... will see... what anwer I can get!

Thanks,
RCP

I have 2 HP 40s. and a mess of 40 parts. if anyone wants them I figure $65 shipped inside the US.