why is using a Weber on a vintage race car cheatin'? I do, and any anything
I do is not cheatin', by definition.
Webers can act funny. Going to a larger fuel jet richens the mix. Going to
a larger air jet leans the mix, by a ratio of 1:3 as compared to a fuel jet
in a DCOE (the air jet change has one third the impact of a fuel jet
change). The main jets, both air and fuel, effect the full throttle
performance but have little effect on normal street running. The emulsion
tube also has a great effect on mixture, but more over the mid-range. The
idle jets effect not only idle but also the normal running below 1/4
throttle on a street car. The pump jets effect the pickup when throttle is
applied.
The action you describe is pretty much what I'd expect if the idle jets are
too small. I'd go up maybe two steps on idle fuel jets. You should get the
highest idle speed when the air screws are about two turns out from bottom
if the idle jets are about right.
Bigger engines sometimes give the carb greater "signal" at the jet orifice
in the throttle body, thus sucking more fuel for a given jet size than a
smaller engine. So sometimes a larger engine can actually use the same size
or even smaller jets than a small engine.
Cheers, Brian
At 05:25 PM 4/13/98 -0400, you wrote:
>Greetings, knowledgeable ones...
>
>Can anyone tell me if going from an .045 to an .055 in a Weber jet is
>richening it?
>
>This isn't a race car dilemna.... (Webers on the Team Thicko Red Rat
>Bastard #99 would be cheating... and that is just not allowed...), but
>on a Volvo 122 Estate wagon. I replaced the original tired B18 with a
>30,000 mile B20 out of my old ES (a tree fell on it).
>
>I transferred the intake & Weber (32/36 DGAV) carb, plugged up the fuel
>injected head, and have tried to tune it, without much success. The
>engine will only continue to run when cold fully choked. If tuned to run
>decent when warm, it won't run without stabbing the throttle repeatedly
>when cold.
>
>I'm assuming that the B20 needs more carb than than the B18. I'm also
>assuming the idle jets need to be richer. Any ideas?
>
>WST
>
>
>
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