Ditching the Kadrons, what now? Progressive or which single bbl?

[ve7kilohertz]

Okay another compression test, engine cold, plugs out, throttle wide open.

1 - 90 add oil 105
2 - 90 add oil 105
3 - 100 add oil 120
4 - 75 add oil 120

Don't know why the others didn't come up to 120 with oil? And odd that 3 is the one that looks rich, it has the highest compression.

Plugs from left to right... 1, 2, 3, 4

Seems like cylinders and pistons will be required....going to have to live with it for this year. no time or $$$ right now. I'll go thru the valve adjustment ONE MORE TIME just to make sure....

So would this be the root cause of the problems?

cheers

[ve7kilohertz]

Further testing...found the rotor wasn't seating on the shaft all the way, went to turn it to check points and it rotated right in my hand. May explain why the timing keeps going off. Turns out the tab inside that indexes it to the shaft, is too wide, wouldn't seat all the way. Weird. Put in a new one, no difference. BUT, I decided to dive into the vacuum advance and just make sure it is working, yup works fine, with me sucking on the hose, pulls 10* at 6" hg, plenty sensitive enough. Measured the carb port again and get good blips to 10-12" but no matter what throttle setting I hold it at, the vacuum bleeds down to 0. That's weird. Shouldn't it stay at say 5 or 6" or whatever it gets to as I raise the throttle? I mean it's exposed to manifold vacuum at this point, probably 2000-2500 RPM. I know from balancing the carbs that the manifold sits at 14" idle and about 17" hg at 2000 RPM. Is it possible this is the problem? Does anyone know if holding steady throttle (in the driveway) will keep steady vacuum at the Kadron vacuum port, or is my behavior typical? Maybe I have a leaky gasket in that area, or cracked insulator?? The vacuum port draws thru all that stuff. I also checked the other carb, same symptoms.

Just thinking out loud.

Going to make up a tee'd line into the passenger seat for the vacuum gauge and go into town to look for a fuel injection system.

Cheers

[FreeBug]

When you're taking your vacuum readings, are you measuring on an idling/revving engine, or are you measuring when you're driving, under LOAD?...you'll get different readings. I just re-read your last post: that's the issue, no load being applied to the engine.

Your initial issue was varying idle, right? Have you tied that varying idle to a varying spark advance? Just trying to see what's up here..

[Lingwendil]

Definitely sounds like a classic linkage issue. I run the original sloppy stock kadron linkage, and it gave me hell for a while until I finally got both carbs synchronized properly at idle. Surprisingly, mine idles like crap until warm, and after about a minute it is smooth as silk... but it only got silky smooth once I ditched my balance tube, and synced it all up with the linkage disconnected entirely. You need to make sure the throttles are equal at several different points and you will need to rev the engine a bit to verify it is set right. Not sure on exact reason why but I've had much better performance with the tube off, but I'm also running original steel manifolds so I'm limited to the 3/8"~7/16" ID of the existing balance tube piping coming off of them
I've had my engine out twice since setting up my linkage, and it is still dead solid and perfectly set even after reinstalling it, carbs are still in sync even.

Don't give up in the carbs, they are fun and easy once you find out what your main issue is

If you do ditch them cheap, I might be interested though, lol
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73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[ve7kilohertz]

Thanks boys!

I just got home from my trip to town....I did find a mostly complete FI system from a late 70's bug... I may pick it up just to play with next year....as I also have 2 other dune buggies to get going and one will definitely be fuel injected...

To answer the questions, yes, the dropping vacuum reading was in the driveway. Yes sloppy linkage I THINK I have pretty well balanced now.

So I went to town with the tee'd vacuum gauge sitting on my lap, and yes, my thoughts of variable timing was foremost on my mind as changing the static timing made a difference in performance. And yes, the stumble came right at light throttle, with the vacuum at about 7-9", value not important as it hits 10* at about 6" so anything over that will be maxed out. Total advance would be about 43*, perhaps too much. I then pulled over and pinched off the balance tube (3/8" fuel line) and tried again. This time...no stumble, ran great, awesome even. The only difference I noticed was just jamming it off the line, a little stumble, probably acc pump not quite right...but otherwise the burble was gone and pulled clean from light throttle and max vacuum to full throttle. Cool!! I need some time to digest this all but I think I may try another vacuum canister, one that maxes at 7 or 8*, or is less sensitive. I have about 4 or 5 of them to play with. I am not entirely understanding the operation of the balance tube, but currently it seems very happy without it.

I was even spinning the 30-10.50-15 rear tires and getting most of the suspension travel out of the front end... he he

Thank you to everyone who (strongly)suggested to keep the Kads. It's not perfect yet but man what a change.

I'll await your comments and thoughts on the changes.

Cheers

PS In the sticky "Official Dual Carb Thread" I will quote Altewagen below, and please, anyone considering duals, take this seriously...apparently it is true. I got lucky by tuning the last inch out of this engine but it should have been easier.

Engine Health

This is the most important part of your carb installation. If there are ANY problems with your engine the dual carbs will usually accentuate them and run like crap! The following items MUST be addressed prior to installation of the new carburetors so that you eliminate any issues that may resemble carb problems when the vehicle is running.

First thing to do is perform a valve adjustment. Next is a compression test. All numbers must be within 10% of each other and preferably above 100psi. If the numbers vary beyond the acceptable limit a leak down test will tell you where the problem is (rings or valves). There is no reason to continue if the engine is worn out.

[Lingwendil]

Glad to see it's working for you!

Do you have any other SVDA distributors? If you get the timing scatter taken care of it should work even better. Might just need to open her up and tighten some bits down. If you really wanted to have some fun hunt down an 019.

Does the pull arm on your advance can have a notch in it to prevent overtravel? Where it exits the can you may be able to bend the stop to block some of its travel.

I changed my weight-stops to give 20° (10 initial, 30 all in, plus 9~ from the vacuum) total mechanical advance, and removed the lighter of the two springs. I swapped the other spring for one of a medium weight, and now I have a pretty nice advance curve, back when had my Sun distributor machine, I played with weights and fooled with the stops enough to give a pretty close curve to the 019 dizzy. Engine is a 1776 but stomps along like a 1915
_________________
73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[ve7kilohertz]

Thanks Lingwendil,

I'll have to have look to see if the can has the stop tab, I know what you are talking about as I have seen them on other canisters. Just checked my notes and see I have a 0 231 172 019 in stock. Not sure what condition it is in, the VW # is 022 905 205P, I show it as a DVDA with a 917 or 601 canister, which I can't find specs for. Shows 1973 Type 4 or 914.

Would love to find a curve machine, rare as hens teeth these days.

Must split some firewood today before engine work....more later.

Cheers

[drumbum68]

Stock Kadron linkage almost always requires a dogleg bend on the right side to get the length proper for syncing. Both carbs opening the same and reaching full throttle the same. They all seem to need the center tower clearanced for full throttle.

[ve7kilohertz]

So I changed out the vacuum canister to the 917 ( no specs) but it seemed to move less than the 505 which I had in there, threw on the timing light and confirmed, 8* instead of 10* advance. Cool. Another trip into town (45 mins round trip) and it worked excellent, no stumble at all. Big smile on my face. It still is better at cruise with the balance tube pinched off, so I may just leave it permanently off. Burbles a little more at idle but I don't drive it much at idle.

Now, funny thing has happened, after I did the compression test (adding oil to confirm rings) one side ( with the low compression on 4) is now smoking all the time at idle. Can't see it while driving in the mirror, but at start and idling, it smokes blue, never did before. What happened? Did adding oil dislodge something that was sealing the rings? Maybe hydrolocked something and broke a ring? Not likely, I only added about 3 TBSP of oil.

Arg!

But happy.

Cheers

[mark tucker]

IMHO adding oil to the cylinder is about the stupidest thing I have ever heard....well in the top 10 any way.

[nsracing]

[[email protected]]

not if you know why you are doing it. If the #s jump up, it's because the RINGS weren't sealing. If the #s stay low, it's because the valves or head seal are poor.

Adding oil is just a diagnostic tool, if you don't have a leak down tester.

[ve7kilohertz]

[surfbeetle]

I ran Kadrons for years with no issues once I figured them out. Remember that when these boxer style engines heat up, due to expansion, the heads move ever so slightly away from the center line of the engine. The engine physically gets wider. When using center pull linkage or the straight bar type like the Kadrons come with, you have adjust your linkage when cold to get it running but then once heated up to operating temperature, it will run like crap. You then have to resync the carbs again while the engine is hot. The car will run okay when cold but will run better when warmed up. There was a thread on the samba where a guy was making a cable pull style linkage that looked like it would eliminate this type of issue.

Obviously, as already mentioned in this thread, valves must be adjusted properly, compression checked and timing set properly. Duals tend to make other issues with an engine more pronounced.
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