My PT-40 is ready to go all but the engine.
I can not tighten the carb or take it out and the retainer and hex nut are now mangled.
I can not get the old retainer out and it is very frustrating. Isn't the retainer supposed to just pop out when the nut is removed?
I am now thinking I will have to take a bus out (don't have a car) to my LHS two cities over to have him correct the problem. But if I can get help here instead it would be greatly appreciated.

Why can I not get the old retainer off to replace it? It is a Thunder Tigre sport .45

G'day Mate,
All you need to do is loosen the nut & the carb will slide out, the cinch bolt does not come out, with the carb in place, if you have mangled it, you have also, more than likely wrecked the carb stub.

Like the previous poster started you cannot remove the cinch pin on Thunder Tiger engines with the carb still in place.

To Remove the Carb:

loosen the hex nut and back it off just one thread but do not remove. The nut will be just slightly away from the case. Now using a small wood dowel that will fit the end of the threads without pushin on the nut and a small mallet gently tap the dowel just once and the cinch pin will move in slightly up to the nut. Do nothing more on the pin or nut.

Just rotate the carb to loosen and it will now easily pop out. Not sure what damage you have done but the pin and nut will now most likely need replacement. I would recommend calling you LHS first as these parts are not carried by many shops.

John

I don't understand. If the retainer can not be removed why do they sell a replacement part for it?
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFW35

And with the hex nut totally removed the carb still will NOT come off. But I can not replace the retainer without the carb coming off. What, will I have to dump an engine simply because of a stripped retainer?

In you first post you said this is a Thundertiger engine however the link you just posted is for a similar part for a Supertiger engine, which is it? Tower does not sell Thundertiger parts and chances are they are not interchangable.

At any rate look at the picture of the part you posted. See that half moon ground on the shaft? That is where the round boss of the carb rides and that jamb pin cannot be removed in either direction while the carb is still in the engine. Period.

Like I said the nut is loosened and a gentle tap on the hex nut end removes the pressure on the carb and the carb is 'twisted' in the engine not pulled and it will fall out. After the carb is removed the cinch pin will slide right out without ever completely removing the hex nut.

Pounding on either end of the pin or severely tightening it will damage the round part of the carburator boss in addition to the pin and hex nut. I would highly recommend you get some help before you cause any further damage. cinch pins may be cheap to replace but carburators are not.

John

My mistake, so sorry. It is a Super Tigre .45

Finally, with a lot of twisting, I got the carb off with no damage. Still can't get the retainer out.

Normally the cinch pin if the nut is removed can slide out in either direction but depending on the damge done to the threaded end its will probably have to be pushed out from the back side (toward the threads) with a proper size punch.

John

OK I got the old cinch pin out and the new one in, curved side facing out. And tightened it as hard as I could. It is tight but the carb still has some give in it and it still shifts about 1/16th of an inch when moved by hand. Is that a significant amount to matter? If I leave it like that will it eventually loosen up again to the point will the pin will have to be replaced again? Is there something I can put around the carburetor to make it even more tight such as epoxy weld http://jbweld.net/products/jbweld.php ?

I remember you were looking for the replacement pin. Can you please check the carb body for dents (where the pin pinches the carb). If you over tighten the nut, it will pinch TOO MUCH and put a dent in the aluminum carb body. This happened to my Super Tiger 46.

Pics would help a lot.

Stripped the nut trying to tighten the nut on the new retainer. Why can't I get it tight? There are no dents or deep scratches on the inside or outside of the carb where the retainer or nut goes. Everything goes in neat as its supposed to, the nut gets nice and tight where I can not turn it anymore but the carb still shifts a bit.

Does anyone know what size nut it takes so that it can be replaced? I think after tightening it as tight as it will this time I will reinforce around the carb with dots of jbweld.

Is there any reason why the base of the carb can not be spot welded with jbweld? There will seem to be the only way to stop it from shifting. If it's Ok I will be getting some tomorrow.

Can not take pics as my camera is damaged.

JB weld will probabaly not hold against slick alum. It might if you can roughen it up some.

I used JB Weld to fill in a small chunk around a muffler manifold before and it dried real nice, very strong.

Been working on it? OK, Ok I apologize just couldn.t resist. Something is wrong with this picture the engine will never run right with a loose carb and don,t start goobering things up with bull snot. If you have not damaged the carb boss the replacement pin may be the wrong one for a larger engine and cannot tight the carb before the thread stops the nut.

Also I have to ask is the rubber 'O' ring inplace around the carb boss and if this is a used engine could it have the wrong carb as a replacement?

This is the procedure for reinstalling a carb that uses a cinch pin:

1. The carb boss with the "O' ring around it is slipped into the engine boss for the carb and pushed right up to the 'O' ring.

2. Now with the needlevalve positioned cross way or slightly aft the palm of your hand is positioned over the carburator throat and your finger wrapped around the bottom of the engine. As you squeeze the carb is pushed down and pushes aginst the O ring and this is where the seal occurs.

3. With the freehand using only a properly fitting nut driver for the hex nut you now squeeze for all you are worth pushing into the 'O' ring the freehand tightens the cinch pins hex nut and this will actually pull that halve moon and the carbs boss tight aginst the crankcass holding everything very tight, there will be no play and the nut only needs to be lightly tightened.

Either you have a mismatch of parts, or missing parts or damaged the carbs boss where the cinch pin rides.

Agine get help at you local club or I can see much further pain in your future.

John

There can bo only only one response here: Get Help

Failure to get help in learning to fly most often results in never acheveing anything.

Failure to get help in learning to operate a glow engine most often results in frustration and fixing problems that may or may not exist.


If you goober that engine up with JB glue then you just might have to replace it for no reason other than you just made it unrepairable.

John

This is the best pic I can take of it. Not much help as the camera is very old and heavily used. The marks around the pin are only scratches, no dings or dents. I will be going to LHS soon as it is possible.

Thank you John for your attempts at helping me, I am a [sm=bananahead.gif] when it comes to engines.

Decided to use my ASP .46 2stroke from another plane. Will be working on the Super Tigre when practical.