1961 Ragtop parked since around 2017 need help with carb tuning.

[USWR]

I am the proud owner of a 1961 Ragtop which was parked in 2017 and hasn't been driven since. It started (with fuel poured down the carb) and ran when I got it, but had a bad fuel line and I couldn't drive it. I've spent the last year doing all the things you normally do to get a car running:

New brakes and lines all around.
New axle seals.
Restored wiring to stock.
New intake manifold.
New muffler.
NOS washer fluid "pump".
New fuel lines (added filter).
Cleaned fuel tank.
Changed oil.
Changed transaxle fluid.
Replaced rotted out ragtop.
Washed and waxed.

After that it started only with starting fluid or raw gas, and drove well, but hesitated under acceleration. Revving at idle also would stumble.

I'm new to carbs, but it was obvious that the accelerator pump was not working. It wouldn't move at all. I replaced the diaphragm and it started squirting gas and I figured that was it.

That fixed the starting issue and it now starts without help, but it still hesitated on acceleration. It seemed to backfire under load too.

Someone suggested doing a static timing and so I adjusted that, and checked that the vacuum advance was moving the plate in the distributor while I was in there. I wasn't sure which mark to adjust the timing to (there are 2 on the pulley) and got conflicting answers online, so I tried both. No help.

I then found some documentation for the car and there was a receipt for an inspection done in 2015 and the mechanic put "needs carb work", so I took that as a sign it probably had carb issues and got a rebuild kit. The carb was filthy inside and I got an ultrasonic cleaner to really clean it. I put it back together, carefully putting the air/fuel screw exactly where it was before I took it apart.

Anyhow, it basically had the same hesitation issue. It seems to run great when the automatic choke is closed, but when it lowers down the idle it get the hesitation problem.

I thought perhaps the carb was tuned over the years to work around the dirt buildup inside it and it probably needed to be adjusted, so I started following the manual (28 PICT) and turn the screw in until the RPMs drop (it's almost completely in at this point) and back it up 1/4 to 1/3 turn).

Still no good. With the carb "adjusted" this way, I get backfires through the carb and through the muffler now when I rev from idle.

I'm not sure what I did, but so many variables are involved (I've played with timing, idle speed, and air/fuel screw) that I don't know which one I messed up and what order to work this problem to get it running well. For the record, I am running 91 octane gas because it's the only kind I can get without Ethanol here in NY. I'm mentioning this for completeness.

This is a one-owner car and I have all the records. As far as I can tell the engine is all original except for the intake and the fuel pump. It has an odd distributor that looks different than the ones I see in pics of other 1961 beetles. The grommet on the coil wire turned to mush and I haven't found a good replacement so I have one that doesn't quite fit on as a temporary fix.

Does anyone have any suggestions how I should proceed and in what order? I feel like it's close to working right and I'd really like to get it on the road and enjoy it. Any help would be much appreciated!

[Dkwautounion]

Something tells me your timing isnt right. You dont seem confident you did that step correctly. I would time it right and then go from there.

Is your float height also set right on the carb ?

[USWR]

[slayer61]

Static timing gets you static verification. Testing timing on a running motor looks at all timing points throughout the rev range. You are witnessing that the advance mechanism(s) work up to, and including cruising speed or full speed.

I don't believe that getting your float level 1/2 mm off will cause poor performance. If you set it to within 1/2 mm of factory specs, that part's gonna be fine.


You'll be a VW mechanic before it's all over... like the rest of us!
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[Eric&Barb]

Might be the original VW grease in the advance of the distributor has turned into so much non-lubricating putty. While the advance might be working still it could be slowed way down. Good time to take the distributor apart for cleaning and new lubrication. Do mark the drive gear and the shaft so you get both on the same direction as before. A center punch on each works well.

That copper plated steel loop between the distributor and carb needs to be up top of that vacuum line to keep fuel from getting down into the vacuum advance and ruining the rubber diaphragm in there. Shorten the vacuum rubber line by about 1/2 to 3/4 of what it is now. Remove the fuel line at the carb and then slide that line thru the vacuum loop, that will keep it upright.

Also the accelerator nozzle might be partly blocked and if you did not remove it for the cleaning.... Have found it often takes two good deep cleaning and sometime three to get a carb free of all the gunk in it, so best to just clean it three times.
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In Stereo, Where Available!

[Eric&Barb]

As for the grommet in the distributor, contact any of the distributor rebuilders in the classifieds for that part.
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In Stereo, Where Available!

[sctbrd]

Level in the carb chamber affects the "head" or pressure of the gas in the chamber to the system. Thats why it's important. Too much, you can run rich, too little you can run lean.
Changing the needle valve gasket 0.5mm will affect the float level more than 0.5mm due to the distance from the pivot point. Ive read 3-4x difference. My PDSIT levels are good with the recommended gasket size, but due to age, previous owner bending the float arm, or the float weight not being correct, the level may need to be adjusted. Easy- run the motor for a bit, pop the cover off and measure the height of the gas from the housing. Youll have to find out what you spec is for your carb.

When you have your carb out, check the accelerator pump discharge quantity. If too low, it could cause stumbling/hesitation. I just worked my way through this same problem on my Ghia. Place the carb on top of a cup of some sort, operate the throttle fully to get the accelerator pump to discharge. Adjust amount by adding washers or moving cotter pin at the end of the linkage-depending on your setup.
I used a children's medicine cap with mL marks to quantify.
Do it 5x or 10x and divide to get one pump for a good average.

A Solex operation sheet I saw once said "Before any adjustment work is carried out, you should be sure that the fuel supply and the entire ignition system are functioning properly".
So, in addition to timing, make sure your points are clean and set correct, condenser is good, dwell is good.
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American in Czech

[tasb]

The ZV/ PAU 4 R 1 distributor is the correct original distributor for 1961 Beetles It looks odd because they were usually replaced by a more modern but not necessarily better 009 distributor- in my opinion.

The R1 delivers about 20 degrees of vacuum only advance so it should be static timed at 10 degrees BTDC. You can then verify that it is delivering no more than 32 degrees of advance at full throttle with a timing light.
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Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

[USWR]

[USWR]

[USWR]

[sctbrd]

"I can also check the accelerator pump. I had seen the recommended adjustment was to move the kotter pin, but the actuator rod on mine has no extra holes. I didn't think about using washers."

My Bentley has a section for adjusting this- on the 32 PDSIT, adding a 1mm washer adds 1.8 cc to the stroke.
It also has a step to bend the pump lever near the spring approx 1mm if the quantity is too high. You can have a look if the arm (lever) looks like it is straight or may have been bent over time.
One of mine wasnt straight when I tackled this issue.
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American in Czech

[USWR]

[Eric&Barb]

[USWR]

UPDATE:
It's been a while but I have some updates on my situation. I had a tree fall and damaged my house roof and didn't have time until this week to follow up with the Beetle.

First off, I checked the timing and I had it wrong. My bad. It's supposed to be 10 degrees BTDC and I had it static timed to 7.5 degrees BTDC. I thought this was the fix, but it still didn't run right.

Following the advice here, I tried to clean the carb again. I found a NOS German rebuild kit in the goody boxes that came with the car, and used that this time. I think the carb is good to go now. The car starts right up, even after sitting for a week, so I think the issues I had with the accelerator pump are fixed.

It still ran poorly after that, and was backfiring a lot, so I thought the timing was still somehow off. When I static tested again, I found it was off again about 2 degrees. That's when I kind of figured out that there's some lash in the gears that drive the distributor and when static timing you really HAVE to back off the crank pulley and then come forward again to take up the lash after you rotate the distributor and only that way it seems to be accurate.

After all of that, I'm still not out of the woods yet. The car starts and idles perfectly now, but it stumbles when making any quick increases in RPM. But it runs absolutely fine when gradually increasing the RPM.

Just sitting still in neutral with the clutch in:
When I go from idle to redline slowly over 5 seconds, it runs awesome.
If I increase the throttle quickly, the engine stumbles. I can see visually that what happens is the engine will burp backwards out of the carburator and this causes the vacuum advance to instantly retard the timing (I can see the plate the points are on jump back). When the advance jumps like this, the engine starts stumbling and burping more and retarding the timing again and again in a cycle that it doesn't recover from unless I let off on the throttle.

Does anyone recognize this symptom and have any suggestions? I'm wondering if this is a distributor issue at this point? Any suggestions would be greatly appreciated!

[Eric&Barb]

As mentioned before:

1. Blocked or partly blocked accelerator nozzle.

2. Old grease in the distributor causing the advance to not work or only slowly.
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In Stereo, Where Available!

[Jeff Geisen]

Worn camshaft
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I Corinthians 4: 1 thru 5

‘63 ragtop - ‘68 single cab

[VW_Jimbo]

What happens if……

With the car not running. Remove the air cleaner. Hold back the choke plate. You should be looking straight down the carb throat and be able to see the throttle plate. As you are looking into the throat, pull the throttle arm. Is there an instant stream of fuel squirting down the throat, the entire pull of the arm?
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[rcooled]

[USWR]