357 carb on 346xp

[shaker223]

3/4 of a piece of alluminum filler rod don't wiegh that much, unless yer from Norway. Why go with a .030" popup when you can go .100" & really wake it up, also allot less work involved. I know the 372's like it. Different strokes fer different folks.

Now sit back & watch the can-o-worms explode:msp_ohmy:

When welding a piston, isn't warpage a problem? Does the heat affect any of the piston's dimensions? Just curious how this is handled.

Thanks.

 

[sunfish]

When welding a piston, isn't warpage a problem? Does the heat affect any of the piston's dimensions? Just curious how this is handled.

Thanks.

Warpage can be a problem.

Must weld a little, then cool piston and repeat.

 

[sunfish]

Does anyone know of a larger replacement carb for the 357xp?

Easy bolt on preferred, but can mod if needs.

 

[shaker223]

I can't help you with that one Sunfish....My question is, has anyone calculated the compression ratio of these saws?

 

[sunfish]

I can't help you with that one Sunfish....My question is, has anyone calculated the compression ratio of these saws?

We check comp with a gauge (PSI). This old 346 is at 165, which is good. Modded they get up around 180-200+. There's probably a simple way to figure the ratio.

 

[J.Walker]

Don't forget those 357 carbs fit the Jonsered 2153wh too.
The other good thing about this swap is no more primer bulb!

View attachment 196222
View attachment 196224



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[sunfish]

Don't forget those 357 carbs fit the Jonsered 2153wh too.
The other good thing about this swap is no more primer bulb!

View attachment 196222
View attachment 196224

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What's all that electronical stuff on your carb?



I ordered another 357 carb..

 

[Terry Syd]

Yeah, what is that attached to the wet side of the carb? Does it interact with the diaphragm?

So what is the difference in size of the venturis from the 346 carb to the 357 carb? I read that the 346 carb is 15mm, what is the 357 carb?

 

[smitty299]

I believe that's a heated carb is it not

 

[sunfish]

Yeah, what is that attached to the wet side of the carb? Does it interact with the diaphragm?

So what is the difference in size of the venturis from the 346 carb to the 357 carb? I read that the 346 carb is 15mm, what is the 357 carb?

I didn't measure them, but the 357 looks about 2mm larger.

I believe that's a heated carb is it not

That's what I thought, but never seen one.

 

[Terry Syd]

Going from a 15mm venturi to a 17mm venturi will give a 28% increase in the area of the venturi. Not a bad swap for that saw at all.

Chainsaw carbs are generally smaller than you will find on kart and aero engines. Here's a formula that will give a range of venturis for an engine - Modifications - Explorer (FLPHG) Powered Hang Glider Harness

I checked my Husky 450 with the formula and came up with a total area of flow equivalent to a 19mm venturi. That sits well within the range of the formula. Of course, the 450 is a strato so I have to add both the area of the 13.5mm venturi carb and the area of the 13.5mm strato port to get my total area of flow.

 

[sunfish]

Thanks for the info, Terry.

I'll study that and measure the 357 carb to be sure.

 

[J.Walker]

What's all that electronical stuff on your carb?



I ordered another 357 carb..

That is the heat element for the Walbro carb.