Difference between 31 pict 3 and pict 4

[hobbybob517]

hi guys,

you would never guess what happend,

it was a cold night yesterday, started cranking my bug,

THE CARB CRACKED!

so i went out and bought a refurbished solex 31 pict 3

when i came home i realised i have a 31 pict 4 , what's the differance?
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[glutamodo]

You can see the differences yourself just by looking at them. The PICT-4 was more refined - the emissions were more highly controlled. Basically it's got temperature-compensation and a redesign of the accelerator pump diaphram and linkage.

And as always, each VW carb was set up for a specific distributor. Varying from this match might work fine and might not. Here's a chart of 30 and 31 PICT carbs and their corresponding distributors - the modification state number is usually found on the base flange of the carb next to the throttle cable attachment - (and if not, it's on the float bowl)

-Andy

[hobbybob517]

Yeah i noticed the accelerator pump was different , i was just wondering if the base is the same, so i can mount it.

as for the dist. i'm about to find out if it will work.

Thanx for the chart btw.
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[glutamodo]

Yeah, if they are both 30 or 31 bases they'll bolt up the same.

[hobbybob517]

[hobbybob517]

Hi guys,

I have installed the carb, my beetle never ran better!

starts on the first turn, picks up like never before.

all i did was bolt it on and set the screws.

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[Tim Donahoe]

That's good news. This weekend I'm going to mount a 34PICT 3 and box up ,y H30/31. Are you running an SVDA single vacuum distributor?

Tim

[hobbybob517]

Yes i am, and have it timed 7.5 BTDC
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[gatordog]

How did you set the screws, I have a Haynes Manuel but not very detailed. I just cleaned the carb and would like to get a base setting. The car always starts great and no idle problem. When going from idle to full throttle it has a bad flat spot and sometimes will die if you don't return to idle.

Once you get it to rev, you can work the throttle and it stops having problems. If you let it idle a few seconds and then blip the throttle it has the flat spot again. I have a 73 with the 34 Pict 3.

I have set the static timing and adjusted the valves. I don't have a timing light so the timing is not perfect, but pretty sure it is the carb

[Tim Donahoe]

gator, get a timing light. Static was okay for John Muir, I guess. Besides, the timing light helps you to see if your advance is working when you rev up the engine.

And what distributor do you have? That makes a big difference with that "flat spot". Yours should be an SVDA, single vacuum/cent. advance.

And to start the 34 PICT 3, lightly turn your volume control and bypass screws all the way in. Be nice--no cranking. Then back both screws out 2 and one-half turns (a good starting place). Then turn in your throttle screw till it just barely touches the choke cam--and then turn it a quarter turn more. Keep it there.

Start the engine. And warm it up. Hopefully you have a tachometer to show you your rpm's. You're looking for 800 to 900 when done.

The whole set of instructions should be in your Hayne's Manual,

Your valves and timing have to be spot on before carb adjustments.

Tim

[Tim Donahoe]

Hobby, I now have to set my timing to "0" degrees with the H30/31, so I was wondering what to set my timing to when I changed carbs.

So the combination of the SVDA single vacuum with the 34 PICT 3 works well for you at 7.5 BTDC? If so, I have to get a new pully wheel with 7.5 showing because my pully only shows the 0 degrees "v" notch. And I want the timing to be perfect when I'm done.

Thanks,


Tim

[hobbybob517]

[gatordog]

And what distributor do you have? That makes a big difference with that "flat spot". Yours should be an SVDA, single vacuum/cent. advance.

How do you tell what Distributor you have? Mine has a single vacuum hose going to the dist. I pulled vacuum on it (sucked on it) and it worked

The whole set of instructions should be in your Hayne's Manual,

The Haynes manual says that since there were so many carbs, etc. that they don't cover in detail.

I have a new problem, I went to mess with the carb yesterday and noticed that the clear fuel filter was dark and there was black stuff half way up in the filter. It must be the fuel lines breaking down, since I pressure washed the fuel tank and blew out the line from the tank. Also the filter was clear for several days and I have not added any fuel. So what and where to find a fuel line that will not breakdown with this new fuel?? I am a diesel guy, and this is my first gas vehicle in almost 10 years.

[hobbybob517]

you can get good quality fuel lines at any garage, just ask for the good stuff, also measure the hole diameter.

as for the flat spot, after you set the timing and valves , turn the volume(small)screw on the left just above the solenoid all the way in (gently) now turn it back 2 1/2 turns let the engine get to opperating temp. once the automatic choke is fully open turn the bigger screw till it idles nicely, then turn the volume screw in about 1/8 turn until the rpms drop just slightly, it should idle at about 900 rpm.

this is your base setting for the carb.

i have this dist, but i have a 31 pict 3 carb now.

it is a SVDA, the stock pulley i had on my engine had 2 notches 1 for 7.5 BTDC and 1 for 0 TDC

if your carb , dist and pulley are orriginal for your engine then you should keep to that setting i guess.
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