Weber adjustment?

Weber adjustment?

Postby Super Brava » Tue Oct 17, 2017 12:17 pm

I've removed the IDFs from the 131 and fitted a Frankenstein dual throat Weber. I've taken the venturi body from a Falcon ADM Weber and fitted it between the ADFA choke top and throttle body. After a bit of chopping and changing main jets I've got the primary and secondary side of it running pretty well, it's much nicer to drive and more tractable than with the IDFs. Unfortunately I can't get a stable idle, the 291 degree inlet cam probably isn't helping, someone did mention that it was too big for a road car. %-( Anyway, it'll run at a bit over 1000 rpm, it sucks fuel in through the accelerator pump nozzle and the auxiliary venturi, the rich mixture causes the idle to drop to about 500, where the extra fuel stops and the revs pick up again, to then repeat. At idle it hunts continuously between 500 and 1100 rpm. So what causes the fuel to be drawn out of the pump nozzle and auxiliary venturi, and can it be easily rectified?
With an M45 you'll all be eaton my dust.
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Re: Weber adjustment?

Postby Bert1 » Thu Oct 19, 2017 10:21 pm

Hi Mick.

Fortunately your issues are pretty easily fixed.











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After 23 years, even more in love than ever.
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Re: Weber adjustment?

Postby Super Brava » Fri Oct 20, 2017 9:29 am

Thanks for that Dave. The car I wish to keep has a primitive version of that, the car I wish to sell just needs to idle long enough for the buyer to get out the driveway!
With an M45 you'll all be eaton my dust.
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Re: Weber adjustment?

Postby 130c » Fri Oct 20, 2017 7:53 pm

Mick,
The cam is a bit big but,
try dropping float level 2 to 3mm, and drill a couple or 4 1mm holes through the side of the emulsion tube into the centre hole (primary throat tube only) up top close to the air corrector jet-this should stop most of the fuel getting sucked out the auxiliary venturi. You won't need to change air corr. jet size to compensate as the problem is being caused by reversion i.e. air flowing in AND back out through the venturi at idle.
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Re: Weber adjustment?

Postby Super Brava » Sat Oct 21, 2017 4:14 pm

You're a bloody champion Doc, I'll give it a go tomorrow.
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Re: Weber adjustment?

Postby Silver 16 » Mon Oct 23, 2017 11:59 am

STUPID QUESTION MICK.......HAVEN'T YOU GOT A STANDARD 2.0L CARB SITTING IN YOUR SHED OF GOODIES ?
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Re: Weber adjustment?

Postby Silver 16 » Mon Oct 23, 2017 12:02 pm

Ah....
Welcome back Rossco.
Hope you enjoyed your leave.
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Re: Weber adjustment?

Postby Super Brava » Mon Oct 23, 2017 9:48 pm

Silver 16 wrote:STUPID QUESTION MICK.......HAVEN'T YOU GOT A STANDARD 2.0L CARB SITTING IN YOUR SHED OF GOODIES ?


Boring! Where's the challenge in that. The ADM Weber has 3mm bigger main venturis. I tried another emulsion tube, less holes at the bottom, more higher up, it was a bit better, so from Ross's suggestion I drilled 4 x 1mm holes near the top. The reversion has reduced, and idle is better, but still quite lumpy. It drives much better, I towed the trailer to the hardware store to pick up some timber, 2 blokes that worked there came up and asked me about it, "Has that got a standard motor in it?" Obviously it's not, but you can't fix stupid. It's much nicer to drive than with the IDFs, with a decent selection of jets I could get it better, but it's good enough to interest a buyer.
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