30 PICT 1 carb tuning

[minskbeetle]

Having issues tuning a 30 PICT 1 carb. Motor is a 1961 1200 cc. Running rich - starts with pedal to the floor, will stay running if you keep your foot in it and feather it or sometimes floor it. If left to itself, engine will die. When restarting, need to floor the pedal as engine is flooded. When driving, sounds like it's running rich, has the occasional extra popping noise. Smells like fuel.

Also, when motor is off and I press on the throttle linkage, fuel squirts out of the little hole on the right side of the carb, where I've put my screwdriver tip in this picture. Don't know if the two are related.

Anyway, I've worked mainly with the newer carbs before, this one is unfamiliar territory. I took the carb off the car, took it apart and removed float, needle and seat, choke, accel. pump and soaked the remaining carb body overnight in cleaner, then washed and blew out with carb cleaner spray. Got a rebuild kit and put in new needle and seat, gaskets, put it all back together again.

Don't know how to adjust the lean/rich on this carb, don't know if I need to pull the jets, replace the jets, or what.

All my books talk about the newer carbs with the two adjustment screws, this one doesn't have the mix screw on the left side like the newer carbs.

Any thoughts on this, or a how to adjust it, would be greatly appreciated!
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72 Super - in pieces
72 Super #2 - awaiting a heart transplant
03 Subie Baja - who doesn't like another boxer motor?

[KTPhil]

30 is a little large for this motor. It originally came with a 28. So if you decide your carb is shot, look for a 28.

The squirt suggests you are missing a small plug/pin there.

Here are some tips on cleaning and adjusting:
http://www.vw-resource.com/28carb.html

[minskbeetle]

Thank you for the link - I read through that and actually had done everything pretty much word for word. What I still don't understand though is how to lean down my carb a bit, or adjust the rich/lean mix like on the newer carbs - or is that not possible? Would I need to correct this by changing the jetting?

You noted that the leak is from a pin/plug missing - should that hole be plugged? Would putting a very small screw or pin in there do the trick? I'm guessing it's possible that when using the compressed air to clean out the carb, if something was slightly loose it could have come out...
_________________
72 Super - in pieces
72 Super #2 - awaiting a heart transplant
03 Subie Baja - who doesn't like another boxer motor?

[Aynthm]

Attach the dwell/tachometer and the stroboscopic timing light in accordance with the instructions.
Note: Again a word of caution -- be very careful to make sure that the dwell/tach and timing light leads do not get tangled up with the drive belt while the car is running.

If you have a single-vacuum distributor (SVDA), remove the vacuum line from the vacuum canister on the distributor and plug it so that air will not be sucked into the carburetor during the following process. Any vacuum lines from the intake manifold must also be plugged, for the same reason.
Begin by turning the Volume Control screw all the way in (not too firmly) and then back out 2-1/2 turns. This is the starting point for the Volume Control Screw.
Start the engine and run it until it is thoroughly warm and the butterfly valve in the carburetor is standing straight up.
Check the engine speed (rpm) and the timing. We're assuming here that your engine speed is way too high and you can't bring it down by adjusting the Bypass Screw in (i.e., the Bypass Screw is already turned all the way in).
Retard the timing as much as you can without stalling the engine. You will note that the idle speed reduces.
Re-adjust the idle speed to 900 rpm by turning the Bypass Screw out.
Re-adjust the timing to 7.5o BTDC, which will once again increase the idle speed to a setting higher than 900 rpm.
Reset the idle speed to 900 rpm once again with the Bypass Screw, which will advance the timing.
Retard the timing and reset the idle. Patiently go back and forth through the steps above; you will finally come to a point where the idle speed is at 900 rpm and the timing is at 7.5o BTDC.
Turn the Volume Control screw one way or the other to obtain the highest idle speed, then turn the screw clockwise (in) until the engine speed drops slightly (by about 25 rpm).
Repeat the idle and timing settings if necessary.
Hopefully that will resolve your idle problem. It worked for me.

[minskbeetle]

I think I'm missing something here. You mentioned adjusting the bypass screw - I don't appear to have one. The only screw I have is the volume control screw. This is what got me screwed (no pun intended) up in the first place as this older carb is different than the 34-3 that I've worked on before (and successfully tuned!).
_________________
72 Super - in pieces
72 Super #2 - awaiting a heart transplant
03 Subie Baja - who doesn't like another boxer motor?

[63RAGTP]

I have two VWs with both carbs you mention. The 30/1 is by far the easiest to tune in my experience. There is only one adjustment screw

I would start by checking your valves and timing and make sure that is all good. Then make sure your points (if you are running points) are set right.

I would look at fixing the leak in the side of the carb before you try to tune it. Once that is fixed if you go by Rob and Daves steps it should adjust just fine.

[KTPhil]

Your carb's single adjusting screw controls the idle mixture only, which actually affects the mixture up through about maybe 2000-2500 rpm.

To adjust the higher-speed mixture you need the change main jets.

It's been a while since I had that carb so I can't comment on what normally plugs your leaking hole. Anyone else? I am thinking maybe a brass pin but it's been like 20 years.

[Aynthm]

[KTPhil]

Looks like the accel pump conduit, so you will get a gas leak every time you press the throttle open. Fire danger, crappy running.

I am not sure how far in that brass pin goes. I think it holds the check ball in place, no? Maybe that is missing, too?

[minskbeetle]

Thank you for the picture, that definitely tells me what I'm missing to plug the hole!
_________________
72 Super - in pieces
72 Super #2 - awaiting a heart transplant
03 Subie Baja - who doesn't like another boxer motor?

[Siggi 66]

You're right, there's only one adjustment screw. If it was me, I'd set the ignitiom timing statically, just to be sure, before touching the carb. That adjustment screw - turn it in all the way, not so hard that you damage the tip, though, then unscrew it about 2.5 turns. Take the top off the carb and ensure the float valve isn't sticking - I have a 30 pict 1 that does that a lot. Put it back together, leave the air cleaner off, and operate the throttle lever quickly to see if the accelerator pump works. (little squirt of fuel into the throat.) Make sure that the choke is set right if it's an electric choke.

Looking at your photos, I'm not seeing the idle control valve, which is a thing about 3 inches long, has 2 wires coming off it, and screws into the carb body beneath the accelerator pump on the right side of the carb as you stand behind the vehicle (opposite side to the throttle lever. Mine was seized, so I disabled it by snipping the end off and taking out the little sliding pin inside it & screwed it back in. I've read that you can just plug the hole and do away with the valve itself as they're a bit of a pain, but I would think leaving that hole open would impair the operation of the carburetor.

I rebuilt one of these carbs a month ago, glad to tell you what I learned if you end up getting a rebuild kit. It's not hard, you can do it with a flat-blade and a Phillips screwdriver in about an hour.
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Money's just something you need in case you don't die in your sleep tonight.

[KTPhil]

[Siggi 66]

Woah, KTPhil!! You're right, he needs to fix the leak, but I'm just passing on what I learned & what other experts like you have told me, dude. Post full instructions to Minskbeetle if you know how to fix his car.
_________________
Money's just something you need in case you don't die in your sleep tonight.

[KTPhil]

I do and I did. See link I posted for details.

[glutamodo]

[oldbusboy]

if a 28Pict 2 carb idles the engine fine, but the green light is flickering on idle.. to speed up the idle I assume I need to close the screw slightly NOT turn it counter clockwise and open it more?

Trevor
_________________
1958 kombi
1968 porsche

[KTPhil]

[bluebus86]

you also need to adjust the float height which can change with different fuel pressure (different pumps installed) so make sure your fuel pressure is right.

that carb is a little big for that motor,


that missing plug and plunger is a show stopper

you see how that little brass plug popped out of your carb?

that happens because the thermal cycling of the aluminum carb body verses the brass plug, the aluminum body eventually opens up a bit, and the brass plug comes out.

the same thing happens to the fuel hose inlet pipe on the carb, and can also happen to the fuel pipes on the pump.
this is a known major fire risk

so not only must you repair that missing plug and ball, you also need to remove the fuel hose pipes, and locktite them into place, and use safety wire on the clamps over the hoses to prevent failure and fire. If the pipes are still tight, then at the very least, add the safety wire.

their are numerous thread on this site about how to safety wire the fuel hoses on the carb and pump. this is a must do, I had one car fire (put out with an extinguisher) and two near misses (fuel hose pipe fell out in my hand) in my VW's

Your lucky that little brass plug fell out, and not the fuel inlet pipe, as that will dump a ton of fuel, right on the sparking dizzie. (ps gravity will drain the fuel tank, so the fire will be fed, even if the engine is turned off.)

So do search on how to safety wire the fuel hoses to carb and pump.
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[Aussiebug]

Minskbeetle,

You've got lots of advice from all over the place so lets see if we can pull it all together.

A few guys think that your carb is a little too big for the 1200 engine. Whilst it's true that VW started out with the 28PCI (20mm throat) on the 1131cc engine and then went to the 28PICT(21.5mm throat) for the 1200 (1192) engines, the 30 series carbs (24mm throat) should work fine with that engine too - some folks even run the 31PICT/3 (European carb - not seen much in the USA) on 1200s and these have the same throat as the H30/31...25.5mm.

You DO need to fix that missing brass pin and the check valve ball it holds in place or no adjustment will work.

The process of adjusting the 30PICT/1 carb is quite simple.

Both my period Haynes and Aussie Gregories manuals agree that the starting point for adjusting the Volume screw is 1 1/4 - 1 1/2 from the closed position (for others reading this - that also applies to the 28 series carbs, but not to the 30PICT/2 - that one starts at 2.5 turns out). Close the Volume screw GENTLY or you can damage the hole the needle valve works in. Idle speed is set at 800rpm with the 40hp engines, using the screw which sits on the fast idle cam. The engine must be warm so the choke is off and that screw sits on the very bottom of the fast idle cam. Now screw the Volume screw CLOCKWISE (inwards) until there is a small drop in rpm, then turn it out a little to restore smooth idling without the rpm drop. Now readjust the idle speed using the fast idle screw if necessary. If you have trouble finding a sweet spot for the Volume screw, it might mean that some ham fisted PO has bottomed it out too hard and damaged the hole, in that case you just have to keep trying different positions until you get the best result you can.

The above procedure is NOT for the earlier 36hp engines with 28PCI or 28PICT carbs - they use 550rpm idle speed, but the rest of the procedure is the same.

It's also NOT correct for the 1300 and 1500 engines using the 30PICT/2 carb, with these you DO want a final drop of 25 idle rpm when adjusting the Volume screw, and you then reset the idle speed to 800 (for the manual - 900 for the semi-auto).

It's also NOT correct for any of the later carbs which have the two adjusting screws (Volume and Bypass) in the left side - the correct procedure for them is described on our site at www.vw-resource.com/34pict3.html

For normal jetting with that carb (when using a vacuum distributor) ball park numbers are 55 idle, 122.5 (just maybe 125) main jet and 125 or 130 air correction jet. Those 3 are the only jets you can change. Try the leaner jetting first (122.5 main and 130 air correction) and if it runs OK at lower revs but tends to struggle at medium/higher speeds, go to the smaller 125 air correction (that jet feeds AIR so smaller means richer). The main jet affects fuel flow right through the rpms range but the air correction jet affects mostly the medium-upper rpms. So if the engine tends to struggle and pop at lower rpms, try the larger 125 main jet.

Idle and main jets are easy enough to find, but air correction jets are not available new, so you might have to scrounge for them at swap meets and in old carbs.

For info, float height should be 12-14mm blow the lip of the float bowl. The height is adjusted by using thicker or thinner washers under the needle valve (thinner makes the fuel level higher and this will run the carb richer too, since less vacuum in the throat will be needed to lift the fuel into the delivery tube).

If you use a 009 (non vacuum) distributor, these will usually work OK (OK but still not GOOD) with the smaller 28 and 30 series carbs, but you might have to use fractionally richer settings (jets) to reduce any flat spots on acceleration. If you do use a 009, set the accel pump for max squirt by compressing the spring on the accelerator pump linkage a little - there are tiny holes to move the split pin up and down that linkage.

Correct timing is important too. The 40hp 1200s use 10BTDC if you have a vacuum distributor, set static. If you use a 009, then it's set at 30-32 degrees max advance at 3000+ rpm and let the idle fall where it may.

The 40hp engine pulleys had either 2 notches close together (7.5BTDC to the left and 10BTDC to the right), or three notches - TDC by itself to the left, and 7.5 and 10BTDC close to each other to the right. If you use a 009, then 30 degrees is 46.5mm to the right of TDC around the pulley rim (or 31mm to the right of 10BTDC if you have a 2-notch pulley).

Hope that helps.
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

[Aussiebug]