Itinerant Air-Cooled

Carb of unknown history. I put in a new rebuild kit and it idled too high. I was told repeatedly to dip it for a couple of days and blow it out, which I did. I reassemble it and installed it and it still idles to high. It starts out on the second step from the bottom of the fast idle cam with a very fast idle. When it drops down one step it dies. I'm guessing that its something very simple but I've no idea at this point.
Ideas please.

You went through the adjustment procedure? Re-checked your timing?


neal

The choke is adjustable too. Have it set where it's on the highest step when cold.
If you've already adjusted the big air bypass screw, then you can fine tune the idle with the step-screw.
Also make sure your carb mounting nuts are good and tight. No vacuum leaks either, good plugs on the extra vacuum ports.

I adjusted the mixture screw 7 half turns out and the bypass screw out 6 half turns. The fast idle cam I adjusted at about .003 or .004.
When cold and not running the choke is on the highest step of the fast idle cam.
Points are at .016 and timing at 7.5 BTDC. The extra vacuum ports are blocked. Carb mounting nuts are checked.
Still idles way to fast.

Whoa. Pretty sure mixture is only supposed to be out 2.5 turns, the bypass screw I'm still confused on. My timing is at 5 degrees, but best is to set it with all the advance in, rpm I forget, but up there, at 30 degrees. I'm a bit fuzzy on the rpm number. Colin would be the one to confirm with, and to get clarity on my fuzziness, as it's what I remember of what he taught me.

A task I need to perform on Bertha still, carb adjust, but my idle is too low.


neal

mentalQtip wrote:Carb of unknown history. I put in a new rebuild kit and it idled to high. I was told repeatedly to dip it for a couple of days and blow it out, which I did. I reassemble it and installed it and it still idles to high. It starts out on the second step from the bottom of the fast idle cam with a very fast idle. When it drops down one step it dies. I'm guessing that its something very simple but I've no idea at this point.
Ideas please.

What year car? What size engine? What type of distributor?

Air bypass carbs (big brass idle speed screw on left) need to have the fast idle screw on the throttle lever backed off until it does not touch the fast idle cam when the choke is fully warmed and open, as you have apparently confirmed.

Choke only runs the engine for a couple of minutes. Then the fast idle speed-up is out of the equation, and then your air-preheater and heat riser have to maintain the idle speed.

If your engine is running too fast an idle when fully warmed up and the fast idle cam is not pushing the throttle lever open in the slightest, who says you can't turn in the big brass idle speed screw a turn or so? Also, timing at 7.5 BTDC may be too advanced. You need to confirm timing at 3,200 rpm to 28* BTDC with no vacuum hoses and let idle timing fall where it may. I am happy to retard the timing 3* or so at idle to help utilize the air bypass, particularly when the 3,200 rpm timing is pushing 30* or so.
Colin

Its an Ak engine, 1600, in a 74 thing. Distributor is 009. I finally took the carb to the Lucky Lab and was told basically that it needed new bushings. I replaced it with another carb and it settled down right away, idle being 900 rpm, and drove it down the street and it was pretty smooth.
Now suddenly the fuel pump seems not to be working at all. but another thread for that.

mentalQtip wrote:Its an Ak engine, 1600, in a 74 thing. Distributor is 009. I finally took the carb to the Lucky Lab and was told basically that it needed new bushings. I replaced it with another carb and it settled down right away, idle being 900 rpm, and drove it down the street and it was pretty smooth.
Now suddenly the fuel pump seems not to be working at all. but another thread for that.

For future reference, many VW 34 Pict3 carbs came with vacuum RETARD distributors with 5*ATDC timing specification. These carbs were DESIGNED to flow a great deal of air for better emissions control. If you try to run a 009 distributor with these carbs, you will not be able to get the idle down because they only work with majorly retarded idle timing. Do not necessarily indict the carburetor for "worn bushings".
Colin

Amskeptic wrote:

mentalQtip wrote:Its an Ak engine, 1600, in a 74 thing. Distributor is 009. I finally took the carb to the Lucky Lab and was told basically that it needed new bushings. I replaced it with another carb and it settled down right away, idle being 900 rpm, and drove it down the street and it was pretty smooth.
Now suddenly the fuel pump seems not to be working at all. but another thread for that.

For future reference, many VW 34 Pict3 carbs came with vacuum RETARD distributors with 5*ATDC timing specification. These carbs were DESIGNED to flow a great deal of air for better emissions control. If you try to run a 009 distributor with these carbs, you will not be able to get the idle down because they only work with majorly retarded idle timing. Do not necessarily indict the carburetor for "worn bushings".
Colin

On the carbs that came with dual vacuum distributors that were timed to 5*ATDC the hole in the throttle plate was larger. 5/32" compared to 1/8" in the single vacuum carbs. The larger hole was to help with the idle because of the retarded timing.

56ovalbug wrote: On the carbs that came with dual vacuum distributors that were timed to 5*ATDC the hole in the throttle plate was larger. 5/32" compared to 1/8" in the single vacuum carbs. The larger hole was to help with the idle because of the retarded timing.

Thank you. It is nice to read a good serious sensible answer.
Colin

I'm running the AK engine in my '71 but with the single advance distributor (bus) and a Brazilian 30/31 carb and drove it to work this morning for the first time- not bad. Good, smooth idle and acceleration. Not sure is this is an acceptable combination of carb/ distributor, but I simply refuse to run an 009 on any daily driver.

VWBusrepairman wrote:I'm running the AK engine in my '71 but with the single advance distributor (bus) and a Brazilian 30/31 carb and drove it to work this morning for the first time- not bad. Good, smooth idle and acceleration. Not sure is this is an acceptable combination of carb/ distributor, but I simply refuse to run an 009 on any daily driver.

Acceptable is what works. Drove it to work for the first time?
Colin

Amskeptic wrote:Acceptable is what works. Drove it to work for the first time?
Colin

first officially plated/ insured time to work, yes. This was last week.

I try to only take this one out on nice days given it's pristine condition. I've considered selling the '72 and driving the '71 until it is ready for sale. Then, make the '68 back into a daily driver.

I don't need 3 beetles- I should give someone else the joy of ownership. I can't believe more people aren't driving old beetles. I'm getting 33 MPG now with a 1641, dual vacuum distributor, oil bath cleaner (now with pre heater pipe connected) and 34 PICT-3 carburator.

also sporting new (used) muffler with new tail pipes (which don't "fweeeem" like original ones did)...a sign of poor quality or a replication that isn't correct entirely?

VWBusrepairman wrote:I'm running the AK engine in my '71 but with the single advance distributor (bus) and a Brazilian 30/31 carb and drove it to work this morning for the first time- not bad. Good, smooth idle and acceleration. Not sure is this is an acceptable combination of carb/ distributor, but I simply refuse to run an 009 on any daily driver.

Weren't the 30/31s used on the single ports, and the 34 PICT 3s on the dual ports? Are you running the 30/31 on a dual port? Trafton* suggested it when I was picking through used 34 PICT 3s chasing issues.


neal

*Proprietor of a small bone yard and shop offering VW repair.

ruckman101 wrote:

VWBusrepairman wrote: Weren't the 30/31s used on the single ports, and the 34 PICT 3s on the dual ports? Are you running the 30/31 on a dual port? Trafton* suggested it when I was picking through used 34 PICT 3s chasing issues.


neal

*Proprietor of a small bone yard and shop offering VW repair.

correct- this 30/31 is a single port carb being used on dual port engine. Seems to be a decent combination with the bus distributor (and still running points currently). I was able to set the timing and idle on this engine- seems to have smooth accelerations, functional choke, and isn't guzzling down the fuel or leaking it out (as was the case with the previous 34PICT-3 that will hopefully be rebuildable at a later date).

I need an oil bath for this engine- anyone have one? Seems like Indiana VW owners are too quick to put on what looks like it should be on a lawn mower!