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Stihl 046 conversion

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Old 11-03-2012, 03:27 PM
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Scota4570
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Default Stihl 046 conversion

I still need to make a mufffler. I have not run it yet. 79cc. 4# 10 oz so far.
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Old 11-04-2012, 01:51 PM
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Default RE: Stihl 046 conversion

Very nice conversion.

Looking in the exhaust it looks ported?

Did you do the machine work?
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Old 11-04-2012, 05:23 PM
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Default RE: Stihl 046 conversion

I did not change the ports. I did all of the machine work. I was hoping to run it today but the muffler took longer than anticipated. This is my best looking engine so far. It just looks like a powerhouse, very svelt an purposefull. Hopefully the performance matches the looks.
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Old 11-04-2012, 06:25 PM
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Default RE: Stihl 046 conversion

The paint dried on the muffler. It turned out way to heavy. I used automotive muffler tail pipe material and turned off about half the wall thickness. Anyone have ideas for thin wall steel tubing? I was thinking of cutting up some old automotive shock absorbers. I found an old vaccume cleaner tube that looked promising but, I was not sure if it was chrome plated or cadnium plated. Cadnium fumes are deadly so I did not use it. I also looked at the local chi-com tool place for a slip roller/ ring roller to make my own tubing without success. Brazing with map gas is working OK. Aluminum solder is no good, it melts when you run the engine. Sounds like an excuse to buy a TIG welder.

I put an HDA carb on it. I also have a big NOS walbro that is big, an SDC 20mm. I see it has only one ajustment screw. Any ideas on how that might work?
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Old 11-04-2012, 08:38 PM
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Default RE: Stihl 046 conversion

Looks great!!

That manifold is very similar to the one I made for my 62cc Stihl. But I am afraid you are going to find you need more heat insulation for the carb. That's what happened to me in testing mine....

The Stihls are like the Zenoahs; they really like to rev, so you might resist the very common urge to overprop it. Let it rev and you'll love it!

AV8TOR
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Old 11-04-2012, 10:08 PM
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Default RE: Stihl 046 conversion

If you are going for light, you don't need a roller to make your own round tubing from flat stock... find some appropriate steel plate (old car hood or something, imports have thinner metal), find something round and sturdy (automotive exhaust pipe should work) and find the circumference, cut a piece the length you want with the other dimension being the circumference of the tube, wrap the metal around the exhaust pipe working your way around, a rubber mallet should help massage things. Once you get half way around fairly close, use a C clamp or two and clamp that half to the pipe then you should be able to work the rest easier. If I had to guess you won't be able to get the ends closer than `" from eachother at this point which should be fine, take your metal and put a hose clamp around it or squeeze it and put vise grips on each end at the seam, then weld that together. Then you can put your bolt tubes and outlet tubes on then cap the ends like you did on the one shown above. If after welding the tube isn't round, you should be able to manipulate it in a vise or on a flat hard surface with a rubber mallet or something similar.

Electrical conduit is usually thinner wall than exhaust pipe, other than that I can't think of anything in the size you are going for.
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Old 11-05-2012, 09:00 AM
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Default RE: Stihl 046 conversion

There were several different Walbro carbs used on the 046 over the years. These exact numbers are probably only available from Stihl but to research the sizes, you may find another carb that will work?

HD-24A 17.6 mm venturi http://wem.walbro.com/walbro/product...-24B&Series=HD
HD-16-318
HD-9A
HD-8-318
HD-11-318
HD-10B
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Old 11-06-2012, 03:59 PM
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Default RE: Stihl 046 conversion

The numbers are in:
22x10 menz
7200rpm
6.1hp

I have not found the timing sweet spot yet.
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Old 11-06-2012, 05:58 PM
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Default RE: Stihl 046 conversion

Sounds great! Congrats!

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