Tuning - any expert advice?

[Basil]

Ok, my 78 Spit has dual Webers and headers and a hot street cam. I know it is running rich so I need to re-jet the thing and also I know the timing is not optimal for the set up. Is there any semi-scientific way to get the pproper jets and timing or is it just trial and error?

Basil

 

[Dave Russell]

Bas,
if you are serious about this:

There are books & books written about how to tune Webers. It would take several pages here to cover it all. Below are two good links which give the answers much better than I could do it in a long series of posts.

https://www.triumphspitfire.com/weber.html
https://www.geocities.com/Baja/Canyon/1017/weber.html

A starting point might be;
Chokes (venturi tubes) 34 mm
Main jets 135
Air correction jets 190
Emulsion tubes F15
Idle jets 40
Idle air bleeds F9
Pump jets 40
Aux. vent 4.5
D

[ 05-11-2003: Message edited by: Dave Russell ]</p>

 

[TR3-2001SE]

Man you sure make me appreciate my SU's!

 

[Dave Russell]

Yeah -- you can see why some people consider the Weber hard to tune. lot of separate jets & adjustments to get right. Not that much better for power than SU's either. However they do look trick. I think that people choose them more for looks & the Weber mistique than practical reasons. They do have their place for serious race engines.
D

 

[Basil]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Dave Russell:
However they do look trick. <hr></blockquote>