from 'D' Jetronic to Twin Carbs

[hughicol]

Have got myself a weber twin carb setup but would like some advise on what distributor and fuel pump to use along with any other suggestions as to tuning etc.

Dave

[Nige]

easiest way is Bosch 009 for the dizzy, these can be had cheap s/hand. I managed to find one off VZi for £25 with working Pertronix module included.

As for fuel pump you'll want a constant 3.5-4 psi, I fitted a rotary one new £49

http://www.vwspeedshop.co.uk/pg/fuelsystem.htm

no need for a regulator with one if these and fitted pretty well in the existing fuel pump location (912e though)

You may need to fiddle with the wiring as the fuel pump relay takes messages from a the Fi for it to be in an ON position.

You can stick with the stock vac dissy but you would need to T in vac lines and an anti pulse valve. I struggled with this setup on mine.

Linkages can also be had from here CB performance one does the job nicely at a reasonable price.

Tuning, I messed about with mine for ages, gave up and took to a local specialist who mainly works on old MGs, he rolling roaded/dyno'd it for £50! Best £50 I spent on it.

You'll also need a breather setup as the Djet runs an enclosed system IIRC?

[Gilbert '71 T]

Hello Dave,

I'm going in the opposite direction to you, Carbs to D-Jet

on carbs I had:

009 Dizzy (with lumention fitted - no points)
Rotary job fuel pump (made a really irritating noise when first switching the ignition on though)
CSP bellcrank linkage from Machine 7

if I have any success with the D-Jet and you're not in a rush most of it might be available. But I won't know for a week or so.

I had the same experience with the 009 as Nige, I spent an age trying to set the car up well but had little luck, but now I'm sure that was due to parts differences within my engine rather than the components above

oh also, don't forget you'll need to plug the D-Jet return line

[hughicol]

Thanks to those who replied. I'm getting up some great advice.

Dave

[fourteener]

On my carb set-up I have the 914 1.8 029 L-jet distributor with the vacuum advance connected to the port on my Dellortos. I can't comment on Webers but the vacuum works fine in this set up.
Trouble with the 009 is it only has about 9degrees of centrifugal only advance so to get to the maximum 30-32 degrees of full advance you need to set it a 21 degrees at tickover. This doesn't make for good low/midrange and is only good for a set up where you're constantly on full throttle (E.g. a bus)

The swap from 009 to the 029 was night and day -oils temps were way down on motorway cruising in 5th (part throttle where you want 35+ deg advance) and MPG was better (not that I've worked it out because the speedo doesn't work -just that a tank lasted longer) and throttle response was greatly improved + smoother.
I would always run a vacuum unit where possible

[hughicol]

Thanks fouteener. My Webers have a vacuum take off on each carb. Can I use the original vacuum Distributor that was with the 'D' Jetronic FI?

If not where can I obtain the 029 one you suggest?

Dave

[Robster]

Hi,

it really is dependant on all the bits synchronising together. the Robster mobile is currently on.....

twin 40IDF's with 32mm venturis, and slightly larger jets. I found that with standard webers that they strangled the car slightly at higher revs due to the 28mm venturis, but with teh above changes, the car revs great. Currently the car runs a little bit rich, but this is better than being to lean. Change of venturis and Jets made a big difference (better) .
I run a 009 distributor, and bosch blue coil, but an 050 is better i believe (it has a more advance so isn't over-advanced at low revs as James rightfully says).
CB performance throttle linkage
Facet solid state fuel pump
Crane XR700 electronic ignition module.
Berg oil breather kit
Scat deep sump extension (extra 1.5L of oil)
Bursch exhaust

Car has run great in this trim for the last 4 years with only oil changes and normal servicing and has been 100% reliable. It is also comparable to fuel injection unless you keep your foot to the floor - then the fuel injection is much more economical.

Throttle can be a bit 'on or off' at low revs in town though, as the carbs are very sensitive at low speed.

Sounds good though!

kind regards
Rob

[fourteener]

Can I use the original vacuum Distributor that was with the 'D' Jetronic FI?
If not where can I obtain the 029 one you suggest?

Dave

Yes the D jet will be fine. If you have ports on both webers then you may be able to connect them both to prevent 'pulsing' although I think cam choice has a lot to do with it. If you look on your distributor it should start with 029 (or something similar) -basically any F.I. 914 unit will work. I think it has 15 degrees of centrifugal advance + 9 deg of vac advance so you can set the tickover much lower. It's been quite a while since I looked at all this but there's loads of good info about this on the shoptalkforum.