Re: Weber downdraft

Jarrid Gross (GROSS(at)unit.com)
Mon, 8 Jun 1998 13:11:00 -0700


---------- From: lauri(at)lorenzo.pp.fi

>Has anyone any experience about one dual downdraught Weber feeding an
>Alpine? I have seen some intakes (Fiat Abarth 1000 Berlina Corsa, for
>example) with such carb system. It takes much vertical space and works not
>as well as two sidedraught ones do, but it was a typical period fit let us
>say in Volvo's.

>I guess it should be assembled one throttle to feed cylinders 1 and 4,
>another for 2 and 3.

I think that what you are talking about would be an IDA or IDF twin weber, which is not a progressive carb like the 32/36 DGV. It would be nice to have one throttle feed 1 and 4, the other 2 and 3, but making the manifold to do this would be quite a chore.

This carb is somewhat taller than even the zenith carbs, and along with the velocity stacks, the height will definately protrude through the hood.

Its a great carb though, and since it is a very popular air cooled VW hop up, cost for a used set is very attractive.

I'd be more inclined to butcher an early manifold (I to IV) and run a dual IDA setup, with individual runners. The carbs would be through thr hood, but thats where all the good air is anyhow, just watch out for sucking up a low flying bird.

Possible carbs for use on alpines (with few or no mods) could be.

1) Series I,II,III with zenith carbs = Weber 40mm single choke (VW replacement for solex 30PIC carb).

2) Series III and IV with twin solex, use 32/36 or 36/36 DGV progressive, or 38 or 40 DFAV non progressive.

3) Series V with dual 150CD strombergs, 2 X 175CD (from volvo/triumph).

4) Series V with dual 150CD strombergs, 2 X H2 SU carbs (from MG/triumph).

Jarrid Gross