New (to me) 1965 1500 Variant S(!)

[sjbartnik]

OK learn me somethin'

So I'm looking at the air intake for the engine. There's a lever on the side that opens a trap door in the top of the intake. When you open up this trap door you have a view to the intake air preheater flap. This flap rotates on a rod that comes out the other side of the intake and has a weight on it. In the position shown in the photo below, the flap is set so that the air intake is from the preheater hose under the intake. This seems to be the default position as that is how the flap is weighted. See photo:

So how is this system supposed to work? There's no thermostatic device anywhere I can see that controls the preheater flap. Just the weight hanging off the end. I'm guessing that at idle, when the engine isn't drawing much air, the flap is "closed" so that preheated air is being pulled in. But when you get on the throttle the air demand of the engine/intake vacuum is enough to overcome the weight and the atmospheric pressure air outside the car forces the flap open against the weight so that cool air is being pulled in instead of preheated air. Is that how that's supposed to work?

And then what's the trap door for? Just an inspection port to see if the flap is moving?

[ataraxia]

You've got the basics of how it works down.

From the 1964 S Owner's Manual:
"The warm air control flap should be checked each time for freedom of movement. This flap regulates the flow of pre-heated air to the carburetor in conjunction with the speed of the engine"

The flap on the top is opened/closed manually to regulate warm/cold air.

The supersession part doesn't have the flap on top, IIRC.

[sjbartnik]

OK now that passage in the owner's manual makes some sense. So the idea is that in the cold months, you are supposed to move the lever so the trap door is open, thus admitting warmer intake air from the engine compartment instead of cold intake air from the air channels in the body.

[EverettB]

[sjbartnik]

I want to pick up a carb sync tool for use with the Square. Everything I've read says that the new production Uni-Syn type made in China or Taiwan are pretty much junk.

So I want to get the snail type; just wondering if anyone knows where to get one with an appropriate adapter to go over the air cleaner mounts on the stock Solex carbs. And SK or BK model?

Too bad there are not vacuum ports on both carbs, I have a nice dual-gauge sync tool that plugs into vacuum ports that I use on my motorcycle.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[EverettB]

For an adapter:
You can use a little piece of plastic pipe from Home Depot or another hardware-type store.

I used to use a little limeade container - same idea.
Here's a super old photo

There are some old Uni-syns in the classifieds if the new ones are junk.

The snail one looks to come with an adapter?
I found this ad
http://www.thesamba.com/vw/classifieds/detail.php?id=1415883
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[sjbartnik]

Yeah I can't tell from the photos if the adapter that comes with the snail is tall enough to clear that air cleaner mounting post. I like your limeade can idea though.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[Bobnotch]

[sjbartnik]

[Bobnotch]

[squaretobehip]

[sjbartnik]

So how smooth are these engines supposed to idle with the dual carbs when everything is dialed in properly? I've seen videos of the FI engines running nice and smooth and of course I expect a little bit more variation with carbs but just trying to get an idea.

This one seems to idle kind of "lumpy" when cold, almost sounds like it's got a hot cam in it except it doesn't.

For the first time yesterday I had a bit of an issue where I fired it up cold and driving away from the garage up through first and second gears it was stumbling and bogging a bit, felt like too rich. Cleared out shortly thereafter and ran normally. It seems to idle pretty well and smoothly when warmed up and runs well and smooth throughout the rev range except for as noted yesterday.

I haven't had the chance to put a tach on it yet to see where it's actually idling; it sounds a little slow to my ear but my ear is rusty for the sound of a VW flat 4 at proper idle speed - it's been a few years. I'm more used to listening to the sound of an air-cooled parallel twin idling at 950 rpm.

I did discover that the vacuum advance hose was super dry, crusty, and stiff, but more importantly, the distributor end of it was all cracked and broken which I found out when I accidentally brushed the hose and knocked it off the advance can. Replaced that with some generic stuff from the local FLAPS while I wait for the proper hose to come in. I'm sure that must have been leaking which wouldn't help anything of course.

Pulled the air cleaner to do that and that's when I observed that the chokes were pretty much fully closed even though the engine still felt quite warm. I noticed that they had been set up on the rich side (marks on choke body rotated more "inward" well past the nub on the carb body) which might explain the stumbling/bogging now that the weather is getting warmer here in NY. I consulted St. Bentley and re-set the chokes to the baseline setting (i.e. where the mark on the choke lines up to the nub on the carb body) and will see where that gets me. Didn't have time to take it for a test drive last night.

Also I know regular idle speed should be ~750 rpm, how high should the high idle be when it's on the choke?

Thanks for all the knowledge you guys are throwing my way. If you find yourself having questions about your Keihin CVK34 carbs, just let me know and I'll be happy to respond in kind.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[Erik G]

smooth. in good tune, should be the same as the FI engine, it is the same engine afterall...

you need to do all tuning while the engine is at full operating temp. Even timing. only thing you should do cold is the valves

cold idle can be a little rougher. Personally, I do not like electric chokes. not so much on type 3's, but on bug's and buses I find them on when the engine isn't cold at all. I mean really, if it's 95 degrees outside, I shouldn't need the automatic choke at all.... I do like early cars with manual chokes
another thing to check is the balance tube stuff. I like my new car with a single side draft, but people say those can be finicky too


everybody else can help you with the rest. I kinda do these things by ear other than distributor timing. I know how they should run and how they should sound. I can usually do the valve adjustment by feel and sound too, but I do go double check before I pop the valve cover back on
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[sjbartnik]

All right, had some fun after work and put together a little YouTube video about the above topic.

This was the first time starting the engine after adjusting the chokes last night to the baseline position. Ambient temps were about 70 degrees F and it fired right up though I held the starter a bit long because I couldn't tell if it caught - seems like idle speed and starter cranking speed were about the same! Seemed to idle at ~600 rpm on the choke just after starting which began to increase as it sat and idled. As it started to come off the choke idle got up to where it's supposed to be, ~750 rpm or so.

Took a drive to warm the engine up and when I came back still around 750 rpm or so so that's all set.

Just curious about the high idle on the chokes as it seems to be not much of a high idle.

Perhaps that's just because ambient temps are what they are. I have no doubt that if I tried this in the winter it would go into a higher idle right off the bat.

Actually what I notice most on this video is it sounds like I've got a bit of an exhaust leak somewhere. Thoughts?


Link


EDIT: Video should be working now.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[Bobnotch]

The video didn't load for me, so I couldn't hear it, but on my own car with dual Solex carbs, I have the chokes in the wide open position (non-op). When it first started up, the idle speed is low, and the engine runs a little rough. But, if you let it warm up a couple of minutes, the idle speed increases about 50 rpm, and the engine smooths right out. I mean you can actually hear it get smoother if you listen to it. Once warmed up, it's as smooth as a FI t-3, as I've got 1 of those here for comparison.
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[D/A/N]

I got an error message about two seconds into the video. Not sure why. But I always though stock base idle speed was supposed to be 850 +/- 50. Unless I'm missing something here?

[sjbartnik]

Fixed video I think. Had it set to "unlisted" instead of "public."

D/A/N, good call. I don't know where 750 got stuck in my head but I just checked Bentley and it says 800-900 rpm should be the idle speed. I will double check that after getting it properly and fully warmed up and if it's still kicking around 750 I'll have to tweak it up a little bit. Ideally I'd like to have it on the higher side of that spec, more air flow for cooling and more air flow for the heater. I dare say that would improve the cold start idling situation as well.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[sjbartnik]

[sjbartnik]

A-ha! I just figured out where I got the idea of 700-750 rpm for an idling speed. I saw it in the "Look/Listen/Do It Better" manual for carb tuning:

So it appears there is conflicting information. Bentley says 800-900 rpm, the dealer level training pamphlet says 700-750. I think I'm gonna go with the Bentley on this one, both for ease of cold starting/improved cold idle, improved generator output, improved cooling air flow, and improved heat flow over the lower spec. Also I think Bentley is the more authoritative source.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[t3kg]

Can't see how Bentley would be more authoritative than Volkswagen.
900 seems like a pretty fast idle to me but whatever runs best is right.
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