30 PICT 2 Tuning

[RONIN10]

Hi everyone,

I'm sending out my H30/31 carb to be overhauled to fix a leaky bushing. In the interim, I'm putting on an old 30 PICT-2 I salvaged and rebuilt from an old, tired engine. The 30 isn't in great shape, but I need to get it working for at least a week or so until I get my refurbished 30/31 back. I did some looking around in the forums, but couldn't find any topics that managed to help me solve my issues (carb related that is). So I have the following two questions:

1. What are the correct initial settings for the throttle arm screw and the volume control screw?

I did find some anecdotal answers to these, but felt I should confirm them. For the throttle arm, I set it much like the recommendations for the 34 PICT-3: just touching the lowest step on the fast idle cam + 1/4 turn (90 degrees). This setting has the engine idling nicely during warmup but as soon as the choke opens fully and the throttle arm just comes off the fast idle cam, the engine starts to falter and leads me to adjusting the volume control screw. I tinkered with altering the throttle arm screw, but it didn't seem to help things any so it is currently left at the setting described above.

For the volume control screw, I initially set it at two turns out (once described as the "sweet spot" for a 30 PICT 2) and proceeded to vary it in or out, trying to get the car to idle without dying. I ended up at a full four turns out and managed to get the car idle for a minute or so, but it kind of petered out before dying. Further adjustments of the volume control screw (outward) would momentarily stabilize the idle, but within ten seconds, it would begin falter again. I've also experienced the car dying after deceleration which seems to be related So this leads to my next question.

2. What is an appropriate range of turns for the volume control screw? More specifically, how many turns outward before the screw no longer is effective? Since my carb won't idle for a prolonged period, it's hard for me to gage. Over four turns out seems like pretty far based on what I've read others being set at.

Relevant details: running a stock 1500 with the stock 205T distributor with new points. Dwell measures 48 degrees, timing is spot on at TDC, valves were adjusted to 0.006 at my last oil change (~1,000 miles ago). They haven't shown any tendency to wander over previous oil changes.

Thanks for any help and insight, folks.

Cheers.

EDIT:

I just took the Bug out for a drive (volume screw at 3 1/2 turns, throttle screw as described above) and found that it sputtered and backfired during acceleration in the lower RPM range of each gear. This means the volume screw is set to be too rich, correct? Low RPM = low throttle = low air = Too rich. Does that logic follow?

I also had to manually control the idle with the gas pedal each and every time I came to a stop. I am going to turn the volume control screw back down to two turns out and do a drive test and see how it behaves then. Will report back soon.

EDIT #2:

Now drove the Bug with the volume control screw set to 2 turns out. Saw the same behavior under acceleration as described in my first EDIT. The sputtering and such seems slightly reduced, but is still very much there under light load. Possible clogged idle circuit? I was pretty thorough when I cleaned out the carb and didn't run into any obstructions in any of the circuits. I also made sure this tank of gas was from a good quality station. Hmm...I'm open to ideas here.

In the interest of full disclosure, I should add the the carb is missing the idle shutoff valve. This shouldn't effect things as it's intent is to stop the engine from running on after the key has been turned off, but I though it merited comment. In the meantime, I'm going to go replace some fuel lines (been planning that for a while). I'll check in later.
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[RONIN10]

Okay, I've changed all the fuel lines and there was no clogs or anything like within them that might inhibit flow at low RPM.

Anyone have any suggestions? Or is this the Friday slump on the forums?
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[keifernet]

[RONIN10]

Yeah, it's in there. I have and will continue to make many dumb mistakes, but not this time. Jetting is as follows: 125 air correction, 116 main, 55 pilot. All matching what Bentley says.

Incidentally, I sent you my 30/31 as we discussed. USPS says it'll be there on Monday.
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[keifernet]

[RONIN10]

No disrespect taken. I've seen enough of your comments on and around the boards to know you didn't intend anything rude.

I've also read how finicky the 30 PICT-2 is. I guess I'm struggling to understand why I can't get a sustained idle at all. It seems like I'd be able to get some kind of idle (rough or otherwise) so long as the other elements (throttle arm screw and volume control screw) are set correctly.
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[keifernet]

[RONIN10]

Thanks for the suggestion. I tried cracking the pilot jet, but to no avail. At this point, I'm sufficiently frustrated enough to just let it be and nurse it to and from work, unless anyone has some other insight, can give me a better starting point for the volume control screw and the throttle arm screw, or has some other suggestion as to what might be awry.
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[keifernet]

After re reading your post I think your trouble might be..

[RONIN10]

I need to find me an old VW carburation engineer to beat on. You'd think they could manage to be consistent on the setting of the throttle arm screw.

I did play with this with no luck, but I was turning it in pretty big increments. I'll play around a bit on it tonight and tomorrow, adjusting it in smaller increments, and see if I can get a steady idle out of it. 1/4 turn increments seem reasonable?

UPDATE: I got some weird sort of stable idle going now, but it only works when I'm sitting in my garage. When I go out and drive the car, it dies every time I come to a stop. The idle doesn't hold a stable RPM either. They just roll up to about 1100 and then roll back down to being on the verge of killing the engine. This behavior is inconsistent though; there is no fixed period between the high and low RPMs.

And lastly, the warmup RPMs are now much higher than they've ever been while I owned this car and that's with the previous owner have the hot idle set to 1200 RPMs (trying to get it back down to 850 - 950 RPMs is what started this whole mess).
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[RONIN10]

This morning was nice. No particular reason to get up and rush out of bed, so my mind turned to the issues I'm having on the Bug and had a moment of clarity burst through my sleep fogged mind.

The 30 PICT-2 (at least mine) does not have a stop on the carb body for the throttle arm even though the specification is to have a .040" gap there. I do have the bracket that the throttle arm return spring hangs on, but it doesn't seem to function as a stop like on other carbs. This makes me confused as to how I'm supposed to set my throttle cable.
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[GTMike]

RONIN10,
I'm curious if you have had any further luck tuning your carb for a good idle. I am having the same issue. I have a N.O.S. 30pict2 that is super smooth in the throttle, but absolutely does not want to idle...well, like you said, I can get it to do something half-assed in the driveway, but when I come to a stop, if I don't nurse it, it'll die. All the mixture settings are providing good power, so I don't want to have to mess with those again. I've already tuned it every which-way from Sunday to keep it from dying at a stop, but no luck.

Anyways, just wanted to see if you came to any kind of conclusion.

-M

[BrianHulud]

[wcfvw69]

[RONIN10]