weber troubles

Phil · Posted: Thu Jun 13, 2002 7:14 pm Post subject: weber troubles

Slight problem with my 32/36dgv. It leans out heaps at really light throttle, around 1250 revs. Because of this, sometimes while cruising it misfires. I know for sure that idle and mains are running on the rich side, so any ideas? Also, don't know if it has anything to do with it, but it leans out while decelerating aswell(in gear that is)
Thanks
Phil

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

You seem pretty confident that its running lean, how do you know? It could be too rich.

If idle and mains are jetted rich, then you have a strange problem.

The fact that it happens at 1250rpm isn't a help, its better to know at what throttle openning it is happening. Throttle openning may be so small as to not let the main circuit start, and it is running on the idle and progression circuit, which is simply too lean.

One good test would be to jet the idle even richer, and lean out the idle mixture (the screw that is), and see what happens. This will keep your idle under control, but richen up at light throttle where 1250 'flat spot' should be'

Do you have the standard booster venturis in place?

Ben Wight

Phil · Posted: Thu Jun 13, 2002 11:53 pm Post subject: Re: weber troubles

I know it's a bit on the rich side because I've got a oxy sensor and a fuel mixture display(one of those pov jaycar ones) I got it so I could jet the weber with a bit less guessing.
It's lean at an extremely small throttle opening. I didn't know how else to describe it sorry, but I had a better look and it's lean from 1000-1500 revs (out of gear) almost exactly.
I understand what you're saying but unfortunately I'm still chasing up that drill set for the jets so I can't have a fiddle with that yet.
I'm not sure if it's standard but the venturi sizes are 3.5 and 4.5 from memory for pri/sec respectively.

Thanks for the help(yet again!)
Phil

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

ok for a quick check pull the idle jet out, and swap it with the one on the secondary side, if that does not work as they may be the same size try it with out the idle jet just to probe the problem is the idle jet.

cheers
Eggy

Phil · Posted: Fri Jun 14, 2002 6:54 pm Post subject: Re: weber troubles

Ok I just checked both of these jets the idle is 55 and the secondary side is 50. I tried swapping them and then richening up the idle screw, it didn't lean out as much(as it was before) but it ran really rough, so I changed them back.
BTW the mains are 150 for both pri/sec and with 175/165 air correctors, this is on a g200 with g180 head + extractors.
Thanks
Phil

Tooleeda · tinkerer Joined: 04 Oct 2001 Posts: 93

Webers are prone to warpage, especially on the top cover plate? Could it be an air leak somewhere here? An excellent fix for this (I had a similar problem) is to use two cover plate gaskets stacked on one another. Seals everyhting really well. Also (Dave) Vizzard wrote a couple of books on these carbs so check them out.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

I would drill out an idle jet to about 70 for primary circuit, and 80 for secondary.

Looks like you are going to have to get those drill bits.

I was thinking that you will have to lean out the mixture screw to counter the larger idle jet so you can get the right mixture at idle, but a bit richer on very light throttle.

Also from memory, the booster venturi sizes are supposed to be 3.5, so I dont think you're problem is there.

Ben Wight