Yet another break in question....

[nitromad]

Hi -

I finally received my sts .28 engine back from the stockist as it originally had a faulty front bearing and wouldn't run. It finally idles, however during its first tank it started to run way too hot (it was still steadily climbing through 260 deg F) when I shut it down as I was afraid it would start to damage itself. The manual says I should be aiming for 210 deg F. I'm pretty sure I had it running nice and rich - there was smoke and fuel spitting from the pipe. The only thing I noticed is that it was idling too high. I tried to use the manual to find the idle air screw (which apparently controls the idle rpm), but it is only pointed out in exploded view - I can't find the thing on the actual engine (newbie I know). Is it possible it was running too hot as it was idling too high? It was revving high enough to just start to engage my four shoe clutch.

Is anyone familiar with the idle control for this engine? Also, is there any other reason why it could have been running too hot?

Thanks

Chris.

 

[Res]

Well, I don't know where your idle screw is specifically, but, on my four screw carb it was (Forgive the ASCII Art)

   Intake -->    ___   __   <-- High Speed
                 | |  / /
Low Speed -->  ======/ /=  <-- Mid Speed (Low Speed Seat adjsut)
                       \\
                           <-- Idle

Also, make sure you're using car fuel and not aircraft. My LHS recommended the wrong fuel when I picked up my car and the temp could not be kept down.

-- Res

 

[DerekB]

Hi -

I finally received my sts .28 engine back from the stockist as it originally had a faulty front bearing and wouldn't run. It finally idles, however during its first tank it started to run way too hot (it was still steadily climbing through 260 deg F) when I shut it down as I was afraid it would start to damage itself. The manual says I should be aiming for 210 deg F. I'm pretty sure I had it running nice and rich - there was smoke and fuel spitting from the pipe. The only thing I noticed is that it was idling too high. I tried to use the manual to find the idle air screw (which apparently controls the idle rpm), but it is only pointed out in exploded view - I can't find the thing on the actual engine (newbie I know). Is it possible it was running too hot as it was idling too high? It was revving high enough to just start to engage my four shoe clutch.

Is anyone familiar with the idle control for this engine? Also, is there any other reason why it could have been running too hot?

Thanks

Chris.

A high idle will cause it to run very hot. Also the recommended temps are not to be taken at idle. You should run it as you would (body on) and drive around for a few minutes then temp.

First thing to do is richen the top a half a turn and set that idle correctly.

 

[nitromad]

I've managed to get all the way through the first tank now, but still have not really fixed the problem. I have it really rich, the main needle is wound WAY out and it was spitting fuel everywhere, but the thing will just not stay cool.

I still can't figure out the idle control, so I used the throttle trim on my controller this time. I got it as low as the controller would let me, but I still feel it was idling too high so I really need to find the adjustment on the engine. As I couldn't get the idle as low as I'd like, I used a fan to keep temps within limits ( I know I really shouldn't do this) and managed to keep the temp around 220 deg F. However, as soon as I stop using the fan the temp just begins slowly and steadily rising till I have to shut it down.

I've attached a photo of an STS .28 mill and pointed out what I think is the idle rpm control. However when I turn it, it doesn't seem to make a difference so I'm not sure. Maybe someone who knows these engines would be able to tell me?

 

[jcchase]

turn your radio and vehicle on. Do not start the engine! take the air filter off and look to see how wide the gap is inside the carb. It should only be 1mm wide. (about the same thickness of a credit card.) If the gap is larger than 1mm turn the screw that you drew an arrow to counter clock wise until the gap is only 1mm. Start it up and see what happens. If you have to turn the idle screw alot then your throttle linkage may need to be adjusted.

jcchase

 

[mrwill]

did you seal it? could be an air leak.