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Cold Air Idle Fix--Step-by-step for 34PICT/3!

Hi all,

Thought I'd possibly return a few favors and post a solution that worked for me...as opposed to asking yet another question. Thanks to posts by Rod Boardman, Jan Andersson, and others.

Bug: 75 SB, converted to carb, 34PICT/3.

Problem: Would start up fine in cold weather (36-50 degrees F), but would stall after auto choke disengaged. Located in Ottawa, Canada.

After reading a bunch of old RAMVA posts (clicked Search), the following worked for me:

- With engine cold, adjust valves (mine already were)

- Check points are at a 0.016" gap (mine already were)

- Adjust timing to 5 degrees ATDC (mine already was)

- Take air breather off and inspect carb., particularly the choke 'flap'. (with Muir book so I could figure out which component was which)

- Start bug and watch choke flap close/open and the time it starts to stall. Play with choke flap to see what it takes to prevent stall. (see how much play I'm dealing with)

- Put palm over top of carb when running. Attempt to create vacuum and suck dirt out of fuel and air channels. Also check for air leaks (stalled immediately so no air leaks assumed).

- Re-adjust auto-choke on right-side of carb. Loosen 3 small screws. Rotate the inner choke cylinder counter-clockwise, so that the part of it facing you moves down. This causes the choke to be stronger and stay on longer. Fasten screws. (come spring/summer, readjust auto-choke back).

- Start engine and test. Put air breather back on.

- Make sure idle cut-off valve is working...(did not have to do this step so I'll skip the steps--search for this topic if it relates to you).

- Set carb by first warming up engine so that choke is fully open. Turn engine off.

- Unscrew Fast Idle Adjustment Screw until it clear of the stepped cam. Screw it in so it JUST touches the bottom step of the cam. Screw in another 1/4 turn (this sets the throttle butterfly to the required .004 inch).

- Turn the Volume Control Screw (smaller screw on the left side of carb) until it bottoms. GENTLY. Unscrew it 2.5 turns.

- Attach dwell-tachometer (or use your ears and listen).

- Start engine and use the Bypass Screw (larger screw) to set idle speed to 850rpm (before this step I had to bottom out Bypass Screw and unscrew 3 turns as a starting point since I frigged around with it too much before).

- Turn the Volume Control Screw (smaller, lower screw) in or out slowly to give the highest idle speed. Turn it in SLOWLY in to drop the idle speed by about 30rpm. (This sets the mixture a fraction rich like it's supposed to be--screwing it in means less air-richer mix).

- Use the Bypass Screw (larger, higher screw) to reset the idle to

850rpm.

Done. I did it!

Tom

Reply to
Bugzai
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congrats Tom....glad you got it...

------------------- Chris Perdue "I'm ever so thankful for the Internet; it has allowed me to keep a finger in the pie and to make some small contribution to those younger who will carry the air-cooled legend forward" Jim Mais Feb. 2004

Reply to
Chris Perdue

Thanks Chris. Not sure if I feel more satisfied that I actually did it...or, the fact that it's the first time that *maybe* someone else can learn from my post.

Can't say I'm the most mechanically literate, but with the help of this great group I've figured out how to replace the master cylinder, replace shift rod bushings, repack seat, adjust timing etc.

Now, if only I could get my wife to like the car. Her first and only time she drove it alone was when the carb was faulty (it either moved or went like a bat out of h&ll with flames coming out the tailpipe). Here's hoping...

Tom

Reply to
Bugzai

i'd say either of those reasons is a reason to feel satisfied....

NO...you *don't* want her to like driving it...seriously...unless you have the time and funds to do a second one while still trying to fix *yours*....i am completely happy that my wife has always just thought the bug was "cute"....

------------------- Chris Perdue "I'm ever so thankful for the Internet; it has allowed me to keep a finger in the pie and to make some small contribution to those younger who will carry the air-cooled legend forward" Jim Mais Feb. 2004

Reply to
Chris Perdue

Good article, well grouped together. A very nice example of what a good SEARCH can do for you. :)

You did good.

Jan

Bugzai wrote:

Reply to
Jan

I personally adjust the choke in my bug in the following manner. Assuming that all other adjustments are done as necessary (timing, points, valves, servicable air filter, good spark plugs,...)

Step 1: Remove the three screws holding in the choke element, remove the electrical wire, and remove the choke element.

Step 2: Place the choke element in the freezer for several hours.

Step 3: Explain to your (wife/girlfriend/mother) exactly why there is a car part in the freezer.

Step 4: Before the choke thaws out, re-install it on the carb, and install but do not tighten the three screws.

Step 5: Rotate the choke element such that the choke plate just closes. No more, no less. Tighten the screws.

Step 6: To assure proper operation, place +12 (or +6, for the pre-'67 crowd) on the choke lead. In a few minutes, the choke should be fully open.

When the choke is at rest (average temp after several hours of non-use), it will probably be open slightly.

Reply to
Jerry Johnson

Hey, was it your stuff I pilfered? I almost emailed you to get the 'detailed carb photo'. Good thing as you've updated your email address from 2000 :) Great explanations!

*yours*....i am

You have a point. Just like today she said I have to tune-up her bike so she can ride it. Turns out that just the tire needs air and she doesn't know how to use the hand pump...and is afraid of blowing the tire up at the gas station pump.

I could go on and on...but she's mastering computers and the internet. Maybe she'll do a search for me on the RAMVA site. Ack!

Signing off now,

Tom must...apologize...to...wife...

Reply to
Bugzai

I thought this a typical mixture screw that makes it richer when you turn it out (CCW). I pretty sure mine works this way on both the H30/31 and the 34PICT3 cause you can smell it.

RT

Reply to
Raymond Lowe

That's right. Turn IN for leaner, turn OUT for richer.

Other than that the advice was dead on.

Jan

Reply to
Jan Andersson

You may need a new carb. The throttle bushing may be so worn that air is leaking through and cannot be set acurately. Get a 34PICT3 non smog carb. I have seen them advertised for as low as $129.00 US. Try California Import at

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My reference books and manuals say that turning the small screw in makes a leaner setting. Too lean is not good. It can fry the engine. Better a little too rich than too lean. You pay more at the pump but that is easier than paying for a new engine. Here is how I adjust me carb: Set the valves too .006 inch gap with engine cold from sitting overnight. Change the plugs. Set the choke. Actually, I set my choke to the minimal setting for cold weather and set to almost none in warm or hot weather. Warm it up and set the timing. On my '73 Beetle with Type I 1600cc DP I set it to 7.5 degrees btdc. Warm it up some more. Drive it 5 miles or more until the oil temp has reached 158 degrees F. Adjust idle to 850 to 900 rpm. Shut it off. Carefully turn the small screw all the way in but do not grind it in and damage the seat. Turn the small screw out 3 turns. Hook up a tach and turn the small screw in until the idle drops about

30 rpm. Slowly turn the small screw out 1/4 turn. This is added insurance that the mixture is not to lean. Recheck the idle and timing. Hey! It works for me! jplikesm73vwbttl
Reply to
Sleepy Joe

For years I was plagued by stalling on by '74 Beetle (34PICT/3 carb) in cold weather (air temperature below 10oC). The car would start fine, but stall as soon as the choke opened. I finally discovered that the problem was a failure of the thermostated vacuum valve that controls the hot air/warm air mix going into the air cleaner. Only cold air was reaching the carb, which according to the manual should receive air at

55oC. My cheap fix is simply to force the air cleaner to take in only hot air in the winter, and only cold air in the summer. I'm sure Bobb Hoover wouldn't approve of this fix- it wastes gas and may introduce some risk of overheating the engine- but it has eliminated the stalling problem. Recently I noticed that an apparently identical valve is used on the A2 Golf, so there may be an abundant supply of spare parts in junkyards.

Garry Ottawa, Canada

Bugzai wrote:

Reply to
Garry Tarr

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I believe you will find the most common advice offered by 'Bobb Hoover' is the need to think for yourself.

As a matter of fact, Volkswagen offered a 'High Latitude' package for engines in Arctic climates that included chromed valve covers, a variety of shutters that fitted over the inlet to the blower housing, an insulated blanket for the bottom of the sump and an air cleaner that offered full-time heating of the incoming air.

When VW introduced the 'automatic' choke they provided three heating elements to be used, as appropriate, for arctic, temperate and tropic climates. Dealer bulletins and Service Notes pointed out that for some regions the range of winter-summer temperature was so wide that the normal twice-yearly adjustment of the choke element (see the manual) would not be sufficient. In those cases the element was simply swapped for one of the proper range.

Thinking for yourself is good. But it's naive to assume Volkswagen was not aware of problems inherent to cold-weather operation.

-Bob Hoover

Reply to
Bob Hoover

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