woodburner

Hi guys,

I have a NIB ST 61 and just bought a suitable tuned pipe for it. My question is:

Should I break in the engine with the stock muffler or is it OK to do it with the pipe (following the manual of course)?

Thanks!

1QwkSport2.5r

Break it in on the stock muffler first. The pipe even if untuned will still boost power and put extra stress on the engine that IMO you don't want to do. Get a gallon through it before piping it. That would be what I'd do.

f16man

I haven't read this hole thread but I used a perry carb to fit my 3250 a bison pitts pipe with the tubes reduced and 5% fuel os glow plug runs perfect......................

Charley

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Hi Guys 'n Gals,

I'm a long-time ST owner (only Saturnos). In the latest MA, I saw an article where the writer said the subject model was powered by ST .35 PDP engines. Never heard of such. Did they exist?

CR

jeffie8696

I believe any baffle ported engine could be PDP modified by sending it in . But I have no first hand experience .

Charley

My Feedback: (2)

I remember that PDP was "Perry Directional Porting." First saw it in HB engines and the K&Bs.

CR

woodburner

Here's a PDP ST:

http://www.ebay.co.uk/itm/Vintage-Su...p2047675.l2557

jeffie8696

How do we know its a PDP? The usually marked the mounting lug PDP.

woodburner

In the case of the Ebay ad I posted it shows on the box and on the manual... I don't know how to recognize a PDP ST from a non PDP.

spaceworm

Here is a pic of an HB PDP with typical PDP stamping on the engine lug:

Bax

My Feedback: (11)

Some engines were made with PDP and were so marked on the packaging. Other engines were modified after manufacture. The modification was done by a few independent engine specialists and by Perry at the time. When crossflow-scavenged engines ceased production in favor of Schneurle-ported engines, PDP went away.

If you look inside the cylinder at the liner, you can see evidence of PDP by the addition of two narrow vertical slots between the exhaust port and the intake port. These served as extra boost ports that helped with the scavenging of spent gasses and the influx of the fresh fuel/air charge.

woodburner

Thanks for the info, Bax!

Charley

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I wonder if Clarence Lee ever converted any STs to PDP. He did lots of K&B 40s; blueprinted & PDP'd.

CR

earlwb

Clarence Lee used to advertise his PDP mod a lot years ago. So there ought to be some other brand engines besides K&B and HB with the PDP mods done to them.
I do not remember the PDP mod being limited to just those two engine brands either. But around that time though, the Schnuerle engines were becoming quite popular and most modellers bought the new Schnuerle engines instead.

downunder

ST had at least one engine with PDP from the factory, the G.60. I have a test on this engine at http://sceptreflight.net/Model%20Eng...20ABC-PDP.html

jeffie8696

I wonder if he could do my ST V60? It could use a little boost.

Charley

My Feedback: (2)

I remember Chinn & his articles. I wonder if he ever did the ST .35 PDP. I knew a guy from El Paso, TX, when I lived there, who had a Bluehead ST .60 that he never used. He wouldn't sell it to me. He's gone now & I've always wondered if they buried it with him. ;>)

CR

Jim Johns

I currently own four Super Tigre engines - an X-25 Bluehead, a Serie X G-60 Bluehead, a Como 40, and a Como 61. My first 40-size engine was a G21/46 that I flew the heck out of first in an Andrews A-Ray followed by an Bridi Trainer 40. The photo shows the Trainer 40 with the G21/46 equipped with a Macs flow-thru (sort of) muffler. It was covered with Permagloss Coverite, which provided a fine carrying case for the crumpled structure inside the day I buried it due to dumb thumbs. I still miss that airplane and engine even though that occurred almost 35 years ago.

The only downside I ever found to Super Tigre engines were the fragile needle valves.

jeffie8696

Do you have a photo of the X60 engine?

eddieC

My Feedback: (2)

Bax, Someone at your booth in Toledo said there may be a return of Super Tigre.

When will we find out for sure?

jeffie8696

I heard the same, and Im on pins and needles.

Charley

My Feedback: (2)

You mean from Saturno?

CR

hsukaria

I went to fly my plane with a Super Tigre G51 (Chinese) and I was seeing bubbles in the fuel line. The engine also quit in flight suddenly. I have just recently replaced the fuel tank and tubing. But I did notice that fuel is bubbling out at the carb HSN assembly. Is there a carb gasket set that I can purchase to rebuild the carb? Or am I going to have to use a sealer of some sort.

1QwkSport2.5r

If you're getting fuel coming out from around the needle, which is normal, then a simple o-ring may need to be replaced. I don't think there is an o-ring in there though. I would find it odd if it didn't leak before and does now. Bubbles in the fuel line will cause a dead stick a lot of times because it leans the mixture so much. I'd be rechecking your new plumbing for leaks though vibration is likely the cause (nucleation). Are you using a new prop?

All of my Tigres leak fuel around the needle valve, even with fuel tubing on the threaded needle holder. (I have 3 different variants of the Mag IV carb). Muffler pressure has its drawbacks.

hsukaria

I changed the fuel tank, but I will replace the tubing again (I can't remember if I used brand new tubing or used pieces). The fuel tubing shows bigger bubbles, not foamy bubbles. So, I suspect a leak, not foaming. But I will add foam rubber around the tank just in case.

To be honest, I got a bit spoiled with the pumper carbs on my 2 gas engines. I don't have to worry about pressure leaks with the gas engines.

I also notice that the compression is getting soft. So, maybe it is time to replace the piston ring while I'm at it. I will aim for the Frank Bowman ring if available.

By the way Tim, did you ever experiment with the carb spraybar filing to increase flow through the venturi?