[Spridgets] Carb dashpot oil.

[Dean Hedin]

It's not that simple.

There is no accelerator pump on an S.U. to enrich the mixture
as you go to a wide open throttle condition (like on a Holley or Webber)

SU's rely on the delayed rise of the piston to force enrichment
when the butterflys go wide open.   The delayed rise is a result of the damper (and
naturally the viscosity of the oil in the damper).

So what happens is when the butterflys go wide open the engine trys to draw more air.
but the piston will not go up instantaniously, so instead the engine draws more fuel through the main 
jet.   This enriches the mixture, which is what the engine needs to accelerate. 

So if you had too thin of oil (or none!) in the dash pots the pistons would rise too fast, and
this would result in hesitation & bucking on acceleration.

As you go more viscous with the oil you will hit a sweet spot optimal for throttle response.

Then when you go too heavy you will have slow engine acceleration and see a puff of black smoke in the 
exhaust as you goose the throttle.


----- Original Message ----- 
From: "derf" <derf247 at gmail.com>
To: "Leo" <60bugeye at cebridge.net>
Cc: "David Ramsey" <dwramsey at att.net>; <spridgets at autox.team.net>
Sent: Monday, February 09, 2009 9:02 AM
Subject: Re: [Spridgets] Carb dashpot oil.


> Yes.
> 
> 
>> Am I correct on this...the heavier the viscosity used for the dashpot oil,
>> the slower the response, the lighter the oil the faster the response??? i.e.
>> the higher the viscosity the greater the resistance to the slide rising and
>> one up the heavier viscosity will slow the return to idle..no demand
>> state...?
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