Weber conversion

[Bill Blue]

Hi, Andy. I posted my own method last month but that was in the old forum. Basically, the so-called "idle" jet as fitted, which also controls the mixture in progression when starting from idle, in many of the Webers as delivered does not suit the Alpine engine. So you get a momentary leaning-out of the mixture until the engine speeds up, resulting in a stumble, or bogging down. In extreme cases the engine will stall on you, which can be a killer. You often won't notice this by blipping the throttle in neutral, it only happens when the engine is under load, i.e. when starting from rest.

Now you can play around by buying a series of increasingly larger jets, but being a skinflint I "did it my waaaaay." I happened to have a set of very small drills which I use in my model railroading hobby. By very small, I mean the smallest are hard to see. For example, the largest one you can see here is 0.036" (36 thou, or 0.91mm), the smallest (which you can't) is 0.013" (0.33mm). You need this kind of set, as each drill increases by no more than 0.003"," or three thou. You won't find them at Pep Boys or Sears Hardware; you need a hobby shop, especially one that deals with micro-modelers like railroaders who scratch-build locos, or maybe a specialty tool supplier.

(Sorry about the poor image. Cheap digital camera that I keep meaning to replace).

You also need a micro-chuck drill. Power is neither necessary or possible, so the drill you use is a one-hand little device with a spiral body (looks like a Lilliputian Bendix drive) and finger pad. You also need patience, as you will need to bore several times in 3 thou increments to get the right result.

Anyhow, I kept boring the jet out and noting that the stumble got progressively less until, at 0.031" (31 thou, or 0.79mm) it disappeared altogether. I went to the next drill, 0.034 (0.86mm) just to err on the safe (richer) side as I reckoned it might need it on a cold start in winter (not that we've had a winter here yet: 60 deg. F again today).

If you go this way, be sure you blow out the jet to remove any drillings before reinstalling, natch.

Nick, did you have to do this after setting the low speed adjustment screw? If so, how many turns were you running?

Bill

 

[Nickodell]

Bill: Sorry, I can't remember. The drill I used [there's a pun there] was to set the idle fast enough not to stall easily - about 1200rpm on the tach, then pick the best mixture setting, and then progressively increase the idle jet size until the bogging-down when starting from rest disappeared. It's a tedious process because you have to put the jet back and do a test drive, then remove it and drill some more, etc., but worth it in the long run [another pun. I'm in that mood today.]

 

[Tom H]

Nick,

I have been trying to follow these posts about the 32/38, and in particluar your advice about drilling out the Primary Idle jet to get a smooth transition from start. In several posts you describe this jet as the one on the driver's side of the DGV toward the front.

But if I understand the DGV, the Primary throttle is the one directly operated by the throttle linkage and that is the one on the (US) passenger side of the carby. So I expect that the idle jet for this Primary throttle is on the passenger side of the carb.

Or am I missing something here?

Thanks,

Tom

 

[Tom H]

Bump. Hoping Nick wil reply,

 

[RootesRich]

Tom, it's pretty easy to figure out which side is the primary. Take the air cleaner off, look down into the barrels and move the throttle linkage. The primary side will open 1st.

Contrary to Nick's opinion, I do not recommend drilling out jets. Unless you have the proper tools and a jig to keep the jet square, one can easily ruin the jet. Factory jets are tested for accuracy and best performance. Additionally, the jets are honed so drilling a jet can create a rougher surface which attracts micro deposits and may result in a need to adjust the idle speed and mixture once in awhile.
I'd pay the few bucks, get the right size jet in the first place and avoid a potential problem down the road.

If you do drill, do yourself, a mechanic, or the next owner a favor and mark out the jetting number to let them know that stamped 50 jet is not a true 50.

 

[Tom H]

Thanks Rich. Yes, I think I understood that pretty well ( which side is Primary), but I was trying to get clarification from Nick about his posts, so I did not misunderstand something. As you can tell from the beginning of this thread, there is lots of opportunityv to get stuff misunderstood.

I like your suggestion to mark out the number on the jet if modified. I think I will do that - if I drill. Now there are two big drilling controveries- to drill or not to drill - ANWR and DGVs !

Tom

 

[Bill Blue]

Thanks Rich. Yes, I think I understood that pretty well ( which side is Primary), but I was trying to get clarification from Nick about his posts, so I did not misunderstand something. As you can tell from the beginning of this thread, there is lots of opportunityv to get stuff misunderstood.

I like your suggestion to mark out the number on the jet if modified. I think I will do that - if I drill. Now there are two big drilling controveries- to drill or not to drill - ANWR and DGVs !

Tom

Tom, I look at drilling as the poor mans jetting kit. Drill, decide exactly which size(s) you need, then buy. Instead of buying a $50 kit, you buy one or two $6 jets. As to confusing future owners/mechanics, I removed the jets from 3 old carbs. I found a 140 jet was larger than a 143 and the smallest was 218! The 143 measured about 40 thou, the 140 about 50 thou, never bothered to measure the 218, but it looked smaller than the 143.

If you are thinking of going to a 70 idle jet, I have one of those that I do not think I'm going to need. I ended up drilling the carb base and going to a smaller idle jet.

Bill

 

[Nickodell]

Bump. Hoping Nick wil reply,

Sorry for the delay. I was searching for where I'd stored the attached diagram. Yes, of course the primary idle jet is on the passenger side, i.e. the right side looking forward. It is part #38.

 

[childa]

webber linkage help

Hi Fairly new to forum as I am from Australia. I have a series 1 which I just fitted a webber 32/36DVG to. I made a linkage which is ok but I see on the forum that I can buy a kit. Has anyone got a photo of the kit fitted to give me an idea and the right place to buy one from? Bit hard to get parts over here is Oz. One company listed is Pierce Manifolds in the States.

Thanks
Andrew