Westy with Flat Spot distributor suggestions

[phat-ass]

So, I've got a '73 Westy that is actually in very good shape. The engine is running very smoothly and the new transmission seems to be in great shape. However, I can't get rid of the "infamous flat-spot".

I'm running a Weber progressive and a .009. I've read, of course, that this is a terrible combination and I've definitely confirmed it. So, I've got 2 questions.

1) is there a way at all to get these to parts to play nice?

2) would I were to switch to a new distributor, which should I avoid?

The van is dangerously undrivable in this condition. I've tuned and tuned and tuned the carb and set the timing in various places. It's not budging. I've even tried a different .009.

What do ya say?

[Wildthings]

I firmly believe that a lot of the problem with the progressive is the power valve. Get rid of the power valve altogether or change the vacuum signal to it and most of the progressives problems should disappear. Note that rejetting is 100% required if you disable the power valve.

Check out the "Progressives Suck" thread everything you need to know is hidden in there somewhere:

http://www.thesamba.com/vw/forum/viewtopic.php?t=217070

[busdaddy]

Agreed, good jetting can solve the flat spot regardless of what distributor you have. SVDA's don't play well with progressives anyways so concentrate on getting the carb optimised first.
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[Tcash]

Hi
Lubricate the dist. advance.

[Bleyseng]

and set the timing to 28 degrees BTDC at 3500 rpm not at idle.
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70 Ghia Black convert-9/69 build date-stock w/133k 1600 SP-barn find now with a rebuilt tranny and engine
77 Westy 2.0L w/Ljet, Camper Special engine-95hp and with LSD!(sold)
76 Porsche 914 2.1L L20c, 120hp Djet (sold)
87 Syncro Westy Titan Red 2.1L 2 knob 100k miles

[phat-ass]

What's the best choice for lubricating the advance if I don't have Bosch distributor lubricant? Does it matter that much? I had thought of that and didn't actually do it, for some reason. We cleaned the advance pretty well, though.

Also, I've timed the hell out of this sucker. I've tried 28-34 degrees at 3000+. The spot occurs at about 1200 RPM, regardless. Which leads me to believe it's the distributor not advancing fast enough or maybe too fast.

I've also gotten this carb tuned about as well as I think possible. The thing purrs at idle and once it's past the flat spot. It's great in gear, Etc. It really does run well. And it hasn't had any problems with the cold, which surprises me (although it hasn't been brutally cold here in NE, yet).

I attempted all sorts of things to tune out the flat spot. Rich, lean, more advance, less advance, Etc. I even adjusted the secondary linkage on the carb.

I will likely re-jet at some point. However, at the moment, I just want to get this thing on the road. It's not drivable with that flat spot.

If I can smooth out that flat spot to a minimum, I'd be happy for the time being.
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Lincoln, NE

1973 Westfalia, Red, Wonderful

Worked on VWs in High School. Getting back at it and loving it.

[Wildthings]

The centrifugal advance mechanism is just lubed with engine oil by putting a few drops on oil on the felt underneath the rotor. You can also use spray lube through the access hole in the body if things are really dry and rusty inside.

If you bend in the stops that limit the movement of the weights you may improve your situation a bit, more initial timing and less advance tends to work better with an 009.

Tuning the idle mixture on the carb isn't going to fix your problems, rejetting is what is necessary, but the problem with these carbs is that if you jet to get rid of the flat spot coming off idle the engine will likely run puke rich at cruising speeds. This is why I feel the power valve is the problem, it is closed coming off idle when you need it open and is then likely open at cruise when you want it closed.

If you know what jets you have in there now you can change them out in only about 15 minutes.

[phat-ass]

No idea what jets are in there now.

I figured out by experience the idle mixture isn't going to do the trick. I couldn't even tune out the flat spot a little bit. This is pretty much what convinced me that it's my distributor. I also didn't think the re-jetting would help because of the same reason.

And I did figure the power valve was part of the problem. The interesting thing, though, is it seems as if the carb is actually dumping fuel into the mix at acceleration. But we could have maybe looked at it wrong.

Is it difficult to disable the power valve?

OH! More initial timing and less advance makes a lot of sense, all of a sudden. I may try that, I'm not terribly optimistic, though.

I'm certainly not attached to the 009, but at the moment, I have no other options (broke, availability, Etc). As long as I don't set it up to cause over-heating, Etc. I'm going to stick with it until I can change it or the carb or both. I'll probably switch to dual carbs next spring. But, then, I'm not attached to that idea, either.

I think it's a matter of balancing my taste in engine build and function. I feel like dual carbs is a bit more fun. Whether or not that actually works better is another story.
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Lincoln, NE

1973 Westfalia, Red, Wonderful

Worked on VWs in High School. Getting back at it and loving it.

[Wildthings]

[phat-ass]

[Tcash]

To link to this post

[mikedjames]

Heat and tuning for transition not just WOT.

Look elsewhere on this site. Cook the manifold with exhaust and feed the carb with 85F hot air in the top. Somewhat more work on a T4.

And the secondary idle jet is not an idle jet it is a main jet at transition and needs sizing appropriately.

On my T1 with essentially a hacked about stock air feed I want to get rid of the power valve but that is more because it goes to 10.1:1 AFR at WOT with the choke off. At cruise it is a more respectable 14 to 16:1

With heat, I can floor my bus on a cold day and it pulls away without hesitation.
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1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
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