[TR] zenith or su's ?

spook01 spook01 at comcast.net
Wed Dec 2 09:33:35 MST 2009


if i were you guys, i would give joe curto a ring since he has worked on the 
carbs longer than most have been screwing them up!
let him select a spring and needle from his lists and send it out to you.
Best,
Ray


----- Original Message ----- 
From: "Anthony Rhodes" <spamiam at comcast.net>
To: <triumphs at autox.team.net>; <wayne at motorcarriage.com>
Sent: Wednesday, December 02, 2009 8:37 AM
Subject: Re: [TR] zenith or su's ?


> >You don't want to compensate for bad Needles with Springs. The Needle
>>Profile or what Jim called "calibrated" is the
>>most important part. Sort the Car out on the road using the Volvo Needle
>>then see where you are rich. At idle or popping on the Highway.
>>Then take it from there. The Springs should be your last concern.
>>Wayne
>
> Wayne,
>
> I'd say that you need to figure out your spring first, since it (as you 
> say)
> determines which part of the needle profile is operational at any given 
> power
> level (and controls the amount of "constant depression").
>
> The way to determine this? Not simple.  You can guesstimate it from the 
> spring
> used on other cars with similar HP and carb choke size.  You can directly
> determine it by looking for just reaching full piston lift at maximum flow
> rate.  Unless you get a child to ride alongside the engine as you race 
> down
> the road, I suppose the only way to do this is on a dyno.
>
> Excessively strong springs will work, but will cause greater restriction 
> on
> air flow than necessary.  I.E.  you have smaller choke carbs!  Excessively
> weak springs will also work OK, until you get to maximum lift.  At that 
> point
> you lose the ability to control the misture with the needle, and the 
> mixture
> is determined as if the carb were a fixed choke type.  Mixture will be
> dependent on airflow to some degree.
>
> Of course you will have to select different needles for the different 
> spring
> rates.
>
> -Tony
>
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