• From: Ontario, Canada
  • Registered: 2005-06-11
  • Posts: 266

Topic: Dual Kadron Tuning ... yikes.

Ok.. so I decided to take my dual kadrons and put them on my 1641 that I just broke in.  They are 40mm and supposedly jetted for a 1600.

I've gotten them to run decently enough so that I can get to 3500 RPM and set the timing at about 30degrees BTDC (SVDA distributor.)  I've got the mixture set (as per AJ Sims / lowbugget site)  It seems to run much smoother... BUT...

There currently is a huge flat spot... If I give it throttle quickly, it just lags and dies.  I've been reading on lowbugget about adjusting the accelerator pump.  He gives a fairly brief explanation of how to set them up, but nothing really quantitative.   

Tomorrow I'm going to check that the accelerator pumps are giving me a good stream of gas as soon as I push them, without any lag.  If they don't, I'll try to adjust them as per AJ Sims' site...

I'm assuming (hoping) that the pump is lagging and this is my issue.  But does anyone else have any ideas?

A related issue is that one of the chokes has always been sticky (from factory, and of course there are no returns on carbs from cip1.ca) and whenever I plug the chokes in, my starter rig fuse blows up.  Last year, I was running these on my 1776 (even though they are jetted for a 1600) and I got them running ok-ish at best with the chokes held wide open.  This meant that I had to sit on the throttle and let the engine warm up before I went anywhere (pain in the ass)   So I'm contemplating getting some cable and rigging up a proper mechanical choke in place of the electrical ones which aren't cutting it.   Any comments or suggestions on that are appreciated.

Is it possible that the choke positions (or one carb's choke not opening or being stuck) would cause this kind of lag?  The one carb seems to flutter and move easily (lets plenty of air through) when I give it gas, but the other does not.

Last edited by thebignic (2010-03-07 17:43:30)

-biggie

thebignic's Website

  • From: B.C.Canada
  • Registered: 2005-01-26
  • Posts: 2,586

Re: Dual Kadron Tuning ... yikes.

A vacuum leak, even a small one will cause a lag like that. So will a wrong dwell setting.

If the choke is the same as stock then remove the electric coil and test how free the choke linkage moves. You will have to free it up if it isn't. A manual choke is nice but difficult in a rear engine car. I wondered about a step motor setup.

Sounds like one of the electric coils is a problem. You must track down the short to ground that is blowing the fuse.

jim

'71 SB(DD only 79K(now 84K miles) & '78 FI Westy (project)
PO of '65 Beetle in '69, '70 Crewcab & '70 Ghia in '77
'71 Super inside rear vents now available
http://www.openroad.ca/volkswebbin/view … p?id=85915
  • From: Ontario, Canada
  • Registered: 2005-06-11
  • Posts: 266

Re: Dual Kadron Tuning ... yikes.

My carb tap is far from professional, so a vacuum leak is possible.  What is the "dwell setting" ? 

The right choke is sticky without the coil on it.  The left one moves freely.

-biggie

thebignic's Website

  • Registered: 2009-06-25
  • Posts: 554

Re: Dual Kadron Tuning ... yikes.

thebignic wrote:

My carb tap is far from professional, so a vacuum leak is possible.  What is the "dwell setting" ? 

The right choke is sticky without the coil on it.  The left one moves freely.

Dwell is the breaker points adjustment. You need to check the specs for your points and set using a dwell meter or at least with a very clean feeler gauge.

About the sticky choke; is it sticking in the fully closed position? If so, there should be a stop adjustment of some type to prevent it from closing 100%, as that is where it is most likely to stick. Throttle blades and chokes should ALMOST close. Exception is an exhaust cutout butterfly valve.

Paul

  • From: B.C.Canada
  • Registered: 2005-01-26
  • Posts: 2,586

Re: Dual Kadron Tuning ... yikes.

My choke on the bug was also sticking recently just as the engine was warmed up. When I removed the coil and rotated it by hand I could feel a rough spot. I sprayed it well with carb cleaner, both on the linkages and shaft. Then I re lubed it. Engine oil on the shaft and black CV grease (molybdenum) on the external linkage. No more rough spot.

jim

'71 SB(DD only 79K(now 84K miles) & '78 FI Westy (project)
PO of '65 Beetle in '69, '70 Crewcab & '70 Ghia in '77
'71 Super inside rear vents now available
http://www.openroad.ca/volkswebbin/view … p?id=85915
  • From: Ontario, Canada
  • Registered: 2005-06-11
  • Posts: 266

Re: Dual Kadron Tuning ... yikes.

Altema: yeah, its sticking in the closed position.  Carb cleaner, more wd-40, a semi-tear down, and some working it back and forth seems to have everything seated properly.  It's not sticking any more.

Also picked up couple of manual choke kits from Canadian Tire.  Unfortunately one of the cables is only about 3 feet long and obviously won't run far enough into the cabin to be of any use, but for my purposes today, they worked fine.

http://www.thebignic.com/vw/1641/manual-choke.JPG

After I installed these, closed both chokes, and started it up, things seem to be a bit more smooth.

I re-set my idle and then re-set the mixture on both carbs.

I let it warm up a bit and gave it some quick shots of throttle and the flat spot seems quite improved now that the chokes are even and the mixture is tuned a bit better.

I haven't checked my points yet, but I will try to make a point (haha.. pun...) to do so.

I checked both accelerator pumps and they shoot a nice stream of gas down the throat of the carb and there is absolutely no lag from slightly touching the throttle to seeing gas shoot out.  So I'm confident that they're set ok.

I took the vacuum line off the distributor and put my finger over it - there appears to be vacuum, but I'm not sensitive or experienced enough to tell if its a significant amount or not.  I have heard that vacuum is lower on a new engine, and will get better as the rings start to break in, so I'm not particularly worried about that yet.

Hopefully sometime this week I'll get another chance to go out and play with it to see how she runs after sitting for a bit and I'll see if the flat spot is still an issue.  I have to hit the throttle pretty darn quick, and pretty darn far to get it to stumble now, and it recovers much faster instead of popping out of the carb... so I think I'm getting much closer.

-biggie

thebignic's Website

  • Registered: 2005-06-02
  • Posts: 427

Re: Dual Kadron Tuning ... yikes.

Nic --you running that thing next week???
I'll listen for ya from the other side of town!

Patty B.
'69 stock bug
  • From: Ontario, Canada
  • Registered: 2005-06-11
  • Posts: 266

Re: Dual Kadron Tuning ... yikes.

Patty: unlikely.  My front end is completely disassembled - doing a disc brake conversion.  And the 1776 thats currently in my car doesn't have any carbs, fuel pump, distributor, etc...   Plus I want to put a new muffler on the bug, and raise the rear end... and no insurance yet...

Might be a few weeks hmm

But you're welcome to stop by and check it out if you're in town.  I can return your book finally! big_smile

-biggie

thebignic's Website

  • From: B.C.Canada
  • Registered: 2005-01-26
  • Posts: 2,586

Re: Dual Kadron Tuning ... yikes.

You can test the vacuum levels at the distributor and the vacuum and centrifugal advance mechanism at the same time with a timing light. There is a chart in the Bentley that relates RPM to vacuum and timing advance.

Do you have a dwell/RPM meter? It's really the best way to check your points.

Here's a good write up on vacuum leaks.

http://www.vw-resource.com/air_inleakage.html

jim

'71 SB(DD only 79K(now 84K miles) & '78 FI Westy (project)
PO of '65 Beetle in '69, '70 Crewcab & '70 Ghia in '77
'71 Super inside rear vents now available
http://www.openroad.ca/volkswebbin/view … p?id=85915