NEW Tee Dee .049 with Hiscott throttle / muffler control NEW

Bob,

If that's the case how does the engine perform with the SPI issue. Seeing as you keep the stock cylinder.

I am wondering that also. I have not run one yet. When I purchased the muffler/throttle I was thinking about putting it on a Medallion and using one of Matt's/Bernie's Tee Dee power non-SPI cylinders. Unfortunately, it is now pretty low on the list of projects.

Bob

I have one I got off eBay a few months ago for $35 plus $5 shipping that was installed on what was described as a TD.051. It appears to have been run a time or two and has the 1702 TD head. Frankly, I haven't taken it apart yet because it is an early piece with no machined flats on the cylinder and I haven't been in the mood to possibly mess up the cylinder. I have an extra TD05RC P/L to provide non SPI running if needed. I was looking for one new on a card but this one came along first. Hard to tell the value since you may find a guy who just has to have one to complete his collection. Will try to start the engine soon as I am curious on how smooth of transition the Hiscott unit is from idle to WOT.

fit90 wrote:I am wondering that also. I have not run one yet. When I purchased the muffler/throttle I was thinking about putting it on a Medallion and using one of Matt's/Bernie's Tee Dee power non-SPI cylinders. Unfortunately, it is now pretty low on the list of projects.

Bob

Well, maybe Prerunner will post back. It does have a 3 fin head on it..... We shall see.

cribbs74 wrote:Bob,

If that's the case how does the engine perform with the SPI issue. Seeing as you keep the stock cylinder.

Bernie sells shims to lift the cylinder, removing SPI for that purpose.

Actually still awaiting that engine in the mail. Bought it from a guy in San Diego for $30 shipped to my door.
Same with the Golden Bee

Both are new.

I just thought they were cool and couldn't pass them up.

RknRusty wrote:

cribbs74 wrote:Bob,

If that's the case how does the engine perform with the SPI issue. Seeing as you keep the stock cylinder.

Bernie sells shims to lift the cylinder, removing SPI for that purpose.

Yeah, I was just curious as to why it was originally marketed as a bolt on affair. Since the TD has SPI then surely it would have affected performance.

Not knocking the engine mind you, it's a neat little piece of history.

cribbs74 wrote:Bob,

If that's the case how does the engine perform with the SPI issue. Seeing as you keep the stock cylinder.

Sorry guys. You lost me. What are SPI issues?

Elgatoprerunner wrote:

cribbs74 wrote:Bob,

If that's the case how does the engine perform with the SPI issue. Seeing as you keep the stock cylinder.

Sorry guys. You lost me. What are SPI issues?

SPI= Sub Piston Induction. Basically the piston extends past the lower edge of the exhaust port and takes in a charge of fresh air to be used in the combustion chamber. It increases engine performance.

When a muffler is added the engine draws in exhaust as opposed to fresh air and it decreases performance.

Usually you either add shims to get rid of the SPI or you install a Non-SPI cylinder/piston to negate the SPI when running a muffler.

Rusty,

You have to monitor engine performance with the shims because they also change the engine's timing. While we have all discussed SPI and exhaust slits and their postiions many times I do not recall ever seeing anything on internal (transfer and booster flute) timing. The several times I have used the shims to eliminate SPI I wound up with an engine that ran badly. I do not know if it was because of intake timing, compression, changed combustion chamber shape or volume, something else or some combination of things.

???

Bob

fit90 wrote:The several times I have used the shims to eliminate SPI I wound up with an engine that ran badly. I do not know if it was because of intake timing, compression, changed combustion chamber shape or volume, something else or some combination of things.

My guess would be compression. By calibrated eyeball, it takes a .020" (half millimeter) shim to eliminate spi on my TD .051, and that drops the compression too much to recover without machining your own glowhead.

It would also shift the exhaust and transfer timing, possibly where the theoretical peak rpm would be beyond anything that intake timing/reed/venturi, primary compression, etc. would support. By four stroke analogy, kind of like having Ferrari cams in a flathead tractor motor.

I have never played with shims but, I do remember reading in one of the mouse building or performance guides that the shims are to be used to ensure the piston crown does not extend past the top of the cylinder. So using them to eliminate SPI would reduce compression like AHRMA mentioned. You could possibly use a #1702 head to gain some of it back but, your best bet would be to just swap on a non SPI cylinder.

This is a shade tree mechanic observation maybe some of our more brainy members can speak about port timing etc.

I received the engine today. There is a 2 stamped on the engine mount. Does that mean its a .051? Is that a good thing? If you guys would like to see some close ups let me know.

This youtube video looks a lot like my muffler. The carb is slightly different.

https://youtu.be/VS3kJz_bVyg

It looks like this thread is in the wrong section of the forum. Sorry. Maybe the moderator can move it.

Anyways I was able to snap some shots of the engines we have been talking about and one more surprise I bought today (already posted it in the cox engine section of the forum)
http://coxengineforum.forumakers.com/t2097-cox-venom-bought-accidentally#30618


Here are some shots of the exhaust throttle valve. This was activated by the trhottle lever, when the idle position was reached. The lever pushes against the spring loaded sliding brass pin, which restricts the exhaust area



Golden Bee NIB

Is this a good way to store these engines. Cool dark place and in a zip lock bag?

This is the package deal I was talking about at the beginning of the post. I really only need a standard .049 for this pod. I'm thinking I should replace it with a more common engine and put the Venom in the zip lock with the other two.

Did you purchase all 3 for $30?

The Venom is your high value piece, while you could run it, your best bet would be to remove it from the pod and display it.

No real way to tell what you have cylinder wise unless you remove the cylinder and muffler. Have you done that before?

Neat engines you have there.

Ron

Elgatoprerunner wrote:It looks like this thread is in the wrong section of the forum. Sorry. Maybe the moderator can move it.

Moved to Cox Discussions. No problem.

cribbs74 wrote:Did you purchase all 3 for $30?

The Venom is your high value piece, while you could run it, your best bet would be to remove it from the pod and display it.

No real way to tell what you have cylinder wise unless you remove the cylinder and muffler. Have you done that before?

Neat engines you have there.

Ron

All three of these engines were purchased last week. I really got luck with the Venom because it was the glider I was after. It was just in the package deal. At the moment I'm trying to contact the seller to find out any history about the engine. Here were the purchase prices

Golden Bee NIB $30.00 shipped to my door
Medallion or Tee Dee with Hiscott muffler and throttle new w/out box $30.00 shipped to my door
The glider package with Venom (appeared to be new) ready to fly for $60.00

As for the engine disassembly part I am pretty good with stuff like that. Unfortunately I do not have the specialty tool that makes it easy to take these things apart without damage to the finish.

Do not use pliers!!!!

Especially on the Venom. It will be worthless if you do.

Wrenches are available here or through vendors. Check the for sale section.

Just found the cox tool in my garage.

I know this is an old thread, but we recently came across two of these units. Both are new, without package and have the instructions. Is there still a market for them?



Best Regards, Matt

I will take them both.

ian1954 wrote:I will take them both.

Based upon the limited research we have done, would be priced at $39.95 each.

Matt