Engine run

I have a reworked tower 40 which 4-2-4 nicely, the
only problem is that it speeds up when doing loops.
as soon as I return to level flight upright or inverted
the engine instantly switches back to a steady 4-2-4.
The engine has approx. 1 1/2 hours of run time. Could
it just need more run time or maybe another head gasket
or maybe different plug?
Any help would be appreciated.
Jay

> I have a reworked
>tower 40 which 4-2-4 nicely,
>the
> only problem is that it
>speeds up when doing loops.
>
> as soon as I return
>to level flight upright or
>inverted
> the engine instantly switches back
>to a steady 4-2-4.
> The engine has approx. 1
>1/2 hours of run time.
>Could
> it just need more run
>time or maybe another head
>gasket
> or maybe different plug?
> Any help would be appreciated.

Sounds like you need a smaller venturi, to me.

Gee, Jay, this is the way I like them to run.

Jay:

A good way to "test" for a smaller venturi, ala Brett (more thatn likely he is right), use one of the green filters. They seem to indicate a logical incremental size reduction and are cheaper / easier than swapping venturis. And they keep twigs and stuff from being eaten.

see Ya

LAST EDITED ON Aug-19-02 AT 07:41 AM (CDT)

You dont say whether it is the same for outside loops and inside loops--if it only speeds up on insides, try adjusting the tank height 1/16" lower in crements until it is the same inside to outsside.

If it is just switching to a 2cycle in the loops, that is what it is supposeed to do.

FWIW

Curt

PS: Who Reworked it??

There are a lot of things that are involved here. Brett could be right that a smaller venturi would help. But maybe it is propped wrong or the fuel is wrong or line length (a little longer, a little leaner to start with).

If you are using high octane (high nitro) fuel, try going to a lower nitro content. You may be able to go to more prop (diameter) or less pitch. What muffler? If a tongue muffler, maybe a screw or two in the exhaust holes. And, yes, lower compression, will make it come on less strong, so a small head gasket increment could help.

With a Tower 40, these use .010 head gaskets. If you are using 5% nitro now, then changing out one .010 head gasked for an OS (.016) can help reduce the amount of "charge" in the loops.

But, yes, also check for upright and inverted. It could merely be the location of your tank, and you may need to raise that just slightly.

Give us specifics. If it is my engine, that is one thing. If it is Randy's or Lew's or someone elses, that is another. But each is set up differently. What prop are you using, muffler, fuel, line length, lap time? It is all important.

LAST EDITED ON Aug-19-02 AT 08:47 AM (CDT)

"[email protected]" doesn't exist.

I am suspicious that the message is a fraud also.

-

Bogus or not, I'm having similar problems on my Tower 40, it hasn't been modified though. But I'll try some of the changes posted here.

Actually, I had stuffed the bypass on the engine, but the darn thing just was unreliable on my Banshee. Then I remembered Leonard saying something about them not being worth a hoot profile where the 35's were. So I unstuffed it and it's been working pretty well with the exception of winding up in the loops. It's managable, but it would be nicer to have a little less power sometimes.

Did I actually just say that?

>LAST EDITED ON Aug-19-02
>AT 08:47 AM (CDT)
>
>"[email protected]" doesn't exist.
>
>I am suspicious that the message
>is a fraud also.
>

Try changing the [email protected] to [email protected]. I suspect with the "q" being close to the "a" on a qwerty keyboard, this may well be a typo.

Sorry about the error on my email, It was suppose to be
[email protected] not Jjpz56aqol.com.I was up very late.
I am running the engine on 5% nitro with 20% castor oil.
Prop is a Zinger 11x5. Engine is mounted on a sig Twister
flying on 60' lines. The engine was reworked by Tom
Muggleton. Because of my work hours I havn't been able
to call him yet, so I thought I would ask everyone here
there ideas.
Thanks everyone.

Tom does a good job on his engines, Jay, so that is where I would start. Head clearance and venturi should be correct for how he sets it up.

I am now wondering if you are running the engine too slow on 60 foot lines. The engine may be just running too rich. What muffler are you using? That's another question. But either a change in prop or a little longer lines where you could run the engine a bit faster might do the trick.

And a little extra zing in the maneuvers isn't all that bad, either. (a "little").

Try running the engine a little faster (rpm) with an 11-4 apc prop. Should be a 2 cycle run with a rich burble when it runs.