douglas racer

I recently bought a beater airplane off a guy with an old Thunder Tiger 46 on it that I'm trying to get running right. He claims it was put away oiled but I had to free up the carb as it was seized. The engine turned over nice though and it seems to have decent compression. I put a brand new glow plug in it and when I first ran it I couldn't get it past half throttle without dieing. After a while it started to run better and I can now get it to full throttle. The problem is, it seems to be down a little on power AND I realized after I shut it down that slightly rich of peak was only 1 and 1/2 turns out on the mixture. Can that be right? I have no manual for it but most of my other engines seem to say about 3 turns out. It seams to me that only 1 and 1/2 turn out would indicate a lack of air but how could that be? It idles pretty nicely and transitions to full throttle nicely but it doesn't sound like its reaching proper rpm's. I have a tachometer somewhere but I haven't been able to find it for years. Any input would be appreciated. Thanks for looking.

JohnBuckner

My Feedback: (1)

Yes one to one and a half turns out does sound in the ballpark but you need to disclose exactly what propeller diameter as well as pitch.

By the way when manuasl suggest a starting needle opening lke three turns out, That is only a rich starting point and final setting will be in more (leaner).

John

j.duncker

My Feedback: (2)

Replace all fuel lines including the clunk line in the tank.

If there is an O ring on the needle replace it.

douglas racer

Thanks guys My other engines run at about 3 turns but going through some engine manuals that I did find online it seems there are engines that suggest 1 1/2 -2 turns as a start so perhaps it is right. All the fuel lines are good, that was the first thing that I checked. I have a 10x4 prop on it which I think is about right. The idle and transition are good so maybe it's just because it's an old engine. I'm going to fly it next week and we'll see how it goes. I don't suppose anyone knows a link to any Thunder Tiger manuals? Thanks for the responses.

MrMulligan

My Feedback: (314)

I had one of these that I ran with a 10x8 or an 11x6. Great engines. I think you're underpropped.

douglas racer

I was actually impressed with the idle and the throttle response. I'll try it with the 10x4 and then find a bigger one.

jester_s1

Yes, a 10x4 is too small. A 10x6 MAS is on the small end, but I used one for a long time on my Kaos. It absolutely screamed in the air with that prop. I use a 10x7 Scimitar now, and the plane has better straight line speed and still turns a lot of RPM in the air.

My needle valve is less than 1.5 turns out at a peak setting, so you are ok there.

Any engine that has sat long enough for the carb to seize needs new o rings all around. The needle valve o rings and the carb o rings will allow air leaks which play havoc on your tuning.