[Healeys] carb oil

[Herbert Miller]

To add to what David said.
Variables that effect piston response.
1.Dash pot spring. There are several available. Mk 1 Sprite had none at all.
2.Viscosity of dashpot oil.
3.Friction between piston shaft and dashpot. The latest HIF44 uses a ball
bearing.
4.I am not positive, but I suspect that the diameter of the damper plunger,
the brass slug on the end of dashpot cap, is a tunable item. Check the cap
for a part #.

All these items combined to generate a mixture curve under acceleration. If
you have a modified engine, cam, CR, ported head, etc. you may have to tune
this curve as well.

Herb Miller


-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of David Nock
Sent: Thursday, August 12, 2010 10:31 AM
To: Oudesluys
Cc: healey list
Subject: Re: [Healeys] carb oil

By raising the piston to fast you will have a lean mixture. Yes you  
will be getting more fuel but you are also increasing the size of the  
venturi which for a short time will lower the low pressure area over  
the jet. This will inturn cause less fuel to be pulled from the float  
bowl. By holding the piston down and accelerating, you are increasing  
the air flow over a smaller area. This inturn increases the low  
pressure area over the jet and pulls more fuel.





David Nock
British Car Specialists
Stockton Ca 95205
209-948-8767

www.britishcarspecialists.com
.
.

On Aug 12, 2010, at 12:01 AM, Oudesluys wrote:

> With SU's to increase acceleration we used to use the thinnest oil
> possible to get the piston up fast and allowing more fuel in.
> Kees Oudesluijs
> NL
>
>
> Richard Ewald wrote:
>> Yes but does that higher flow rate more than offset the increased  
>> thickness
>> of the needle due to the piston not rising?
>> Venturi vacuum is very weak, and I can't see where even if the  
>> venturi
>> vacuum doubled it would overcome the lack of jet area.
>>
>> On Wed, Aug 11, 2010 at 7:20 PM, Michael Salter <
>> msalter at precisionsportscar.com> wrote:
>
> [demime 1.01d removed an attachment of type text/x-vcard which had  
> a name of coudesluijs.vcf]
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