Two Stk

[Rcmaster199 at aol.com]

Warm fuel will assist the vaporization. With care tho, to   disallow vapor 
lock. And most vaporization does happen in the crankcase due to  partial vacuum 
effect and heat there. But enough happens in the venturi to act  as 
refrigerant for the carb body and that can cause freezing and ice build up.  Also, the 
sudden expansion of the inlet air  as it enters the crankcase  just past the 
venturi, can't be ignored either.
 
The dynamics are complex and depend on ambient conditions but the concept  is 
fairly simple once the fundamental is understood: evaporation is a cooling  
process
 
MattK
 
In a message dated 3/1/2005 8:58:16 AM Eastern Standard Time,  
bob at toprudder.com writes:

e heard  of heating the fuel before it goes to the
carb (on automobiles) improves  the vaporization and
can increase mileage. Don't know if it is true,  but
sounds plausible.

I believe the majority of the vaporazation in  our
engines occurs in the crankcase (two strokes), not in
the carb. I  also think that this process helps cool
the engine internally, especially  the piston.

This reminds me of a problem I had with a generator  a
couple of years ago. Ran fine for about 30 minutes,
then would start  running erratic. Finally, I figured
out it was carb ice. Click the link  below to see the
quick fix for it. Ran a piece of dryer vent from  the
cylinder head around to the intake. Got me through the
2003 ice  storm, no power for several  days.

http://www.toprudder.com/photos/feb03/carb_heat.jpg

Bob  R.

--- Rcmaster199 at aol.com wrote:

>  
> The action  of converting liquid fuel to a vapor in
> the venturi is a part of   
> the refrigeration cycle. It requires energy to do
> it, which  comes from several 
>  sources. The most important source is the  lower
> than ambient pressure as the 
>  piston drives to  compression, but ambient air and
> crankcase heat contribute   
> also, once the engine has reached steady state.
> Insulating  the carb body 
> places  different demands on these sources  of
> vaporising energy. 
>  
> Potentially, it may  reduce air temp further which
> may have a supecharging  
>  effect. I think you are after improved sealing
> between the carb body  and the  
> throttle barrel, but this could be an added  benefit.
>  
> Interesting idea Nat
>  
>  Matt
> In a message dated 2/28/2005 9:02:14 PM Eastern
> Standard  Time,  
> natpenton at centurytel.net writes:
> 
> The  carb is a potent refrigerator. Most carb case 
> heating comes from  ambient 
> air, not from engine case conductance. The engine 
>  crankcase though, should 
> be well ventilated. The  situation may  be better
> with a plastic bushing for 
> mounting the carb  to  engine case, although I have
> not done so.  Nat
>  
> ----- Original Message ----- 
> From:  _Dean  Pappas_  (mailto:d.pappas at kodeos.com)  
> To: _discussion at nsrca.org_
>  (mailto:discussion at nsrca.org)  
> Sent: Monday, February 28, 2005  1:49  PM
> Subject: RE: Two Stk
> 
> 
> Did you  turn down the carburettor boss to make a gap
> that's filled  with  
> vinyl?
> If  not, then it's an awfully thin bit of  insulation
> that provided the 
> desired  effect.
>  later,
>     Dean
>  
> Dean Pappas  



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