Will a bad vac can on a 205A effect my idle?

[bhartwell59]

Hey all,

043 905 205A dizzy with a 34pict3 carb. Done all the vac leak tests, readjusted the carb plenty of times, checked valves, new plugs, checked the plug wires and points. Fuel pump is fine. Last fall, cleaned out my intake manifold heat risers.

Idles great...but...sometimes stalls while in gear. 

In researching this, I came across a couple of posts stating the vac hose to the dizzy, when sucked on, should move the two plates inside... just a little. Did that with no joy. So I greased up the inside plates and freed them up (they were pretty frozen). Still have no plate movement with the sucking technique.

So now I think the vac can is old and just not supple any longer. How much would this effect my idle while in gear?

What do you guys think?

[volkenstein]

bhartwell59,
                 IMHO, your car would've been really sluggish. Sounds to me like you have more than one issue at work here. You should have an SVDA, which is non-functional at idle anyway. Having your car unable to return to idle in gear, points at some other leak source in my mind. You have '74, which IIRC is loaded up with more emissions stuff - hence more places to be leaking.

Given you have done your points plate to free it up, what about the advance mechanism? I can imagine a lot of "possibles", but I would see if you can get a Vac can anyway as it does sound like it has blown.


HTH
Volkenstein

[bhartwell59]

I do have an SVDA. All emissions stuff have been taken off. Charcoal canister (which is played out I'm sure, still has hoses connected to it... if that means anything). I'll get a new vac can... who knows how old it is. It doesn't seem as pliable as it should.

In gear, the idle just seems to eventually get weaker and then finally stall.

Where/what should I check for the "advance mechanism"?

Thx!

[volkenstein]

Bhartwell,
             Pop off your distributor cap, and try and turn the rotor. One direction it shouldn't move, the other it should move and then spring back if you let go. If it feels locked up/no movement/teensy bit - your centrifugal advance isn't functioning. BTW - thumb & forefinger...not a "Stillson wrench force" .

HTH
Volkenstein

[bhartwell59]

Turned the rotor CW about 1/4" and it sprung back. CCW no movement. So it seems my centrifugal adv is working.

Still need that new vac can...on the list.

[sb001]

bhartwell, if it's any consolation my autostick has been like that for years. It always idles just fine in neutral, right around 950 or so RPMs with engine warmed up, but when I put it in gear with engine warmed up the idle speed in gear drops to around 725-750 or so. Which is OK at first but then as I keep driving it, as the engine gets hotter and hotter, eventually it will lower the idle at stops to where the oil light and sometimes the generator light comes on. Every single time, in the history of driving this car, if I just blip the throttle the tiniest bit, the issue goes away but as soon as I take my foot off the gas, it goes right back down to lower idle. I have tried and tried to compensate by adjusting the carb, etc -- but nothing matters, the idle speed in gear ALWAYS eventually gets to the same point. Pop it back in neutral and both the idle speed (RPMs) and the timing are absolutely fine. IMO it HAS to have something to do with the vacuum signal being borrowed from the carb/ intake setup for the autostick system. Although I will say that it hasn't stalled out on me in a good long while, it sometimes makes me think it's going to. I am not saying there isn't something wrong with your vacuum canister, but IMO if that were the case your car would not drive properly at all.

[bhartwell59]

Hey sb001,
haha, you're right... you can not let your guard down with our autostick's! my idle is great but i'm always alert to the idle speed when in gear at stoplights.

i think i found my vac issue (a slight tear in the manifold to cv hose). as i said, when tracking down the stalling problem, i did find the inside plates on the 205A vac can weren't moving when the suck test was applied. a new one is on the way. what effect it will have remains to be seen... probably nothing but it'll be updated.

this all started when i replaced the oil cooler seals, added the hoover bit and slapped some foam around the oil cooler. i guess taking the fan shroud, etc off to get to the oil cooler really upset the rig! first it was the idle cut-off valve that went (had an extra to swap with) and now this issue.

i know enough not to call victory quite yet... but i'll be reporting back.
-B

[bhartwell59]

well, put the new vac can on and still had the stalling when hot. well, not stalling but idle rpms dropping low.

when this happens it runs rough...herky jerky/missing? in gear. i d say it was the condenser but there is no backfiring present... and the condenser test doesn't raise a red flag. turning the car off then starting up (without a cool down) gets it running perfect. odd

for lack of any other ideas, i have a new coil on the way.

ugh

[68autobug]

Hi, Does Your automatic choke work correctly... I find they need to be adjusted in winter and again in summer. Not sure about the 205A , but My Vacuum advance stopped  working not long after I installed Pertronix electronic ignition in a new Distributor.
Have You have fitted a hard start relay on the ignition so the coil will get more power? makes starting better. also another relay to put maximum power into the starter motor.. 2 x standard relays are all is what is needed. 
You won't need points and condensers with a pertronix ignition kit... No more checking points etc....
  A condensors life wasn't long, they were replaced frequently along with the points, rotor button plus the distributor cap. spark plugs, and even the spark plug leads were replaced along with the dust plugs and the VW  lead ends..

LEE  Noonan

[bhartwell59]

i'll check the choke... although, it starts okay. no hard start but have thought about one.   

plugs are new... wires/dizzy cap 10 months old. spark is getting to the plugs just maybe not as strong. could be the condenser (tested good tho). a new condenser is cheap enough... as is a new fuel pump. i don't think this is a fuel delivery issue.

i'll see what the new coil does and report back.

[67vetteal]

How about a Voltage check? Coil, Grounds etc.

[sb001]

I posted earlier in this thread about having a similar issue. Well I went to a local VW show this past weekend, and drove my car in a parade they have, and it started doing the low idle. Someone came up after the parade while I was tinkering with it with the engine running (still low idle), and told me to pull the air cleaner off the top of the carb. I did, and IMMEDIATELY the idle went back to normal! I did this a few times and every time the idle went back up to where it should be. He asked me the last time I had cleaned my air cleaner out and I sheepishly admitted that it had been months, maybe over a year. The air flow that is supposed to come through the air cleaner after warmup was being completely blocked by all the crud collected by the mesh inside the cleaner lid. I had a spare aftermarket paper element air cleaner with me so I swapped them out temporarily and have not had the low idle issue again so far.

So if you are having this problem, and have the original stock air cleaner, try the test of pulling it off the carb (after engine has warmed up completely to where you are getting the low idle issue) and see if the idle jumps up. If so, try cleaning out your air cleaner thoroughly and see if it solves the problem.

[bhartwell59]

Wow... sb001, that's an interesting possible cause. like you, i sure hadn't thought of that. yes, i do have the stock air cleaner (off to the right side of my engine) which i replenished with oil in october but didn't clean the fiber filter. guess i should.

67vetteal... new coil, strong spark to plugs. got a new fuel pump coming but i don't expect that to change anything.

but the air cleaner deserves a looksy... haha, this weekend in fact!

[sb001]

Wow... sb001, that's an interesting possible cause. like you, i sure hadn't thought of that. yes, i do have the stock air cleaner (off to the right side of my engine) which i replenished with oil in october but didn't clean the fiber filter. guess i should.

67vetteal... new coil, strong spark to plugs. got a new fuel pump coming but i don't expect that to change anything.

but the air cleaner deserves a looksy... haha, this weekend in fact!

Good luck on this solving your problem, I was really surprised to see what kind of difference it made just lifting that air cleaner off the carburetor. I still do have a bit low idle but not like what it was-- hoping that after I get that air cleaner cleaned out and put back on and change my oil it will run well.

[bhartwell59]

cleaned the air filter element and don't really see any change. needed cleaning anyway.

sb001: as tmea stated in my "low idle" thread... humidity seems to have something to do with things. have you noticed this also?