PDSIT carbs on 2.0 liter engine

[mcdonaldneal]

[mcdonaldneal]

Also, I'm not sure that air jets go smaller than 130, one size down. I'll check ACN.
Edit: looks like ACN goes to a 110.
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1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[busdaddy]

Try it with the bigger mains and see how it behaves, the mid range numbers will be interesting as well as overall fuel consumption. It's nice that you have the meter to see the results in real time.
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[SGKent]

most carbs 3 air jets = 1 main. Air jets are used to change the slope not the overall mixture. I'd change the mains and see what happens from mid-range to WOT. If that is too rich compared to idle to mid-range come back one air jet at a time. You are basically going to detune your engine to keep it running cooler. Wish it wasn't so but the 2L engine just makes too much heat. That shroud was made for a 1700 engine and the market pushed for more torque to sell cars. Almost all the foreign cars did that in the 70's and early 80's. Take Nissan (Datsun) 240 Z , 260 Z, 280 Z (2.4L, 2.6L, 2.8L); Fiat went 14.4L, 1.6L, 1.8L, 2L etc. Everyone was boring out the engines and/or lengthening the stroke.
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[mcdonaldneal]

We'd been away for the weekend but I had chance to make a little progress this evening. The new main jets are in. I've checked the valve gaps stone cold. Pertronix looks after itself.
After warming up the engine I set the timing to 7.5deg btdc at idle, which is the stock spec, and as it happens that gives 28deg maximum advance (tbh, the max advance is not super stable, but it sits at near enough 28deg).

I've not even started setting the carbs up, idle mixture etc, as it was getting dark and I needed to eat!
I'll let you know.
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1978 marino yellow Bay Dormobile camper
1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[Tcash]

Have u lubed your distributor lately.
Lubing the Distributor

[busdaddy]

[mcdonaldneal]

Yep, timing was with hose off (it’s vac advance only, no retard on the Aussie bus).
Distributor is lubed but this one is not refurbished and greased. Maybe I’ll use the opportunity to swap in a freshly refurbished one so that everything is as good as can be.
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1978 marino yellow Bay Dormobile camper
1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[Tcash]

Ya with your timing moving around at max advance, the rebuilt dist would be a good idea. Might be worth looking at your dwell at RMP also.

[mcdonaldneal]

Ok. Sorry for the delay here, didn't have time to work on the bus during the week!
Trying to improve an overheating condition in fairly stock setup, I have increased the main jet size from 132.5 to 135. 140 air correct jets and 55 idles.
I ended up changing the distributor for a refurbished one, Pertronix ignition, timing 28deg at 3000rpm, hoses off.
I worked through Colin (Amskeptics) dual carb procedure, but these NOS carbs don't have mixture screws for the main carb part of the circuit (see pic). So, I adjusted idle mixture using the finger on/off the hose technique.

My first short test run shows that the bus is behaving ok, good acceleration. When warmed up:
Idle AFR is 12.3 (was 13)
40mph 13.5 (was 15.5)
50mph 13.5-14 (14.5-15.5)
WOT IN 2nd gear 13.6-13.7 (was 13.5)

This seems OK to me, but I did weaken the idle mixture when I got home, to 13.5. I will probably see how things look with this setup as far as temps and driveability go and I'll try to update the thread.
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1978 marino yellow Bay Dormobile camper
1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[busdaddy]

I'll bet there's screws hiding beneath those pressed in plugs.
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[Tcash]

[busdaddy]

[mcdonaldneal]

Good to know about the screws. I've not made any effort to uncover them through. At the very least I think we can assume that they are balanced: left to right, and the mixture hose test suggested they were a little lean, which fits with Colin's method, letting the CIS run slightly rich to even up.
These carbs had a part number for a type III.

So, I went for a proper motorway test run, with the AFR better positioned so I could see it in the mirror.
In 'general running', driving moderately hard, the AFR actually stayed fairly stable at cruising speed:
13.5-14 at 40-60mph
13.8-14 above 60 and even to 70mph plus
Wide open throttle seemed to be about 13.0-13.5
Idle also about 13-13.5

I think I'm pretty happy with that. I guess, as Busdaddy suggested, you could put a smaller air correction jet in, to richer at the high rpm end, but I'll leave it all just now.
I did manage to drive the oil temp dipstick up to 'flickering' when I was pushing uphill, into the wind at 70mph plus, but that's hardly surprising! It cooled down when I backed off a bit.
Thanks to those who gave advice, and hopefully this can stay as a zombie thread that still has a bit of value in it!

Final settings were:
Idle jets (solenoid) 55
Main jets 135
Air correction 140
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1978 marino yellow Bay Dormobile camper
1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[mcdonaldneal]

Ok, keen to hear thoughts here.
We had a days driving, with four people in the Kombi today, jets still as per the last post. Mostly winding country roads, speeds about 50-60mph, never really more than 60mph.
Observations:
When travelling at speed I was aware of a slight 'fuel' smell. I wondered if it could be unburied fuel from rich running, but the test runs suggested AFR of 13.5-14 at those speeds, so surely not?
After one, fairly short uphill stretch at 60mph the 'save my bus' dipstick light came on fairly strongly and the oil temp gauge was about 120degC (250F). Now, that doesn't fit with rich running, but would fit with an AFR of 14-15. I would never have had those temps before I fitted these new carbs. The engine did feel hotter than usual once we stopped as well.
Checked the timing when I got home, 28deg max with vacuum hoses off.
I'm not sure what to think. Maybe my next step is to do some extended running with the AFR connected? The fuel smell might be a red herring, but the lines from the tank all the way to the carbs look good with no sign of a leak.

Bright ideas?
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1978 marino yellow Bay Dormobile camper
1969 signal orange Karmann Ghia convertible
1976 martini olive Bay Dormobile camper

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[busdaddy]

It's highly unlikely you would smell a mixture or unburnt fuel issue in the cab, unless you have massive exhaust leaks.
My 72 would get a gas smell inside during mountain driving on bendy roads until I fixed the vent elbow and filler neck hose, could also be the sender gasket or another vent line connector.

Drive with the AFR connected, maybe there's a fuel tank venting issue that's leaning it out after a while?
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[wcfvw69]

Agree with BD. If you haven't changed your fuel filler hoses and vent lines in the gas tank area, there's a HIGH probability you're getting smells from them. My 70' bus had a fuel smell with the tank fuel. Pulled the tank and found the original 45 YO rubber fuel hoses and vent hoses. Replaced them and all fuel smells are gone.
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[Tcash]

Evaporative Emission Control EVAP/Charcoal, Carbon Canister

Thanks to mayor rattle
Fuel Hoses
http://www.ratwell.com/technical/FuelHoses.html

Good luck
Tcash

[xyzzy]

+1 on the hoses and charcoal canister making a huge difference.

I'm in the process of converting my 2.0L back to the original 73 dual solex PDSIT, in the same jetting as you and @satchmo and others ended up with: 135 mains, 140 air, 55 solenoids.

Unable to get it running right yet. but getting closer (hopefully)
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1973 VW Westfalia 2L hydraulic, dual Solex PDSIT
1987 VW Vanagon Westfalia

[orwell84]

I was going to suggest the canister. My bus had a fuel smell for decades, which persisted in spite of changing all the usual suspects except that I never had the charcoal canister. I always assumed all ACVW's smelled this way a little. After I installed a new canister and plumbed it properly, the fuel small went away completely. On rare occasions, I get a quick whiff of fuel when stopping after coasting, but that with a Weber single carb with not much tuning in it.

Following your progress as I hope to set up my original PDSIT's this summer superbly rebuilt by Volkzbitz. They are off my original 1700 and my current engine is an 1800. I find the idea of changing over a little daunting but I love the idea of having all that those carbs have to offer; air preheat, a real air filter, adjustable accelerator pump stroke, a quiet intake...

Best of luck with your tuning