34 PICT 3 Adjustment Woes

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sgkent
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Re: 34 PICT 3 Adjustment Woes

Post by sgkent » Tue May 09, 2017 8:37 am

Latest post of the previous page:

I bottom out the large screw
sounds like you have looked at the setup carefully. If the above is the main thing you are concerned with there are only three or four things I know that can cause an engine to race like that.

1) The timing is sticking too advanced
2) There is an air leak into the manifold allowing the engine to run fast
3) The fast idle circuit is defective or out of adjustment
4) the idle return spring, cable etc are not allowing the engine to fully fall back to the idle stop, or the idle stop / throttle plate position screw is not adjusted correctly.

Be aware if this car has never run right since you purchased it that sometimes a common hack is to drill the throttle plate to let more air thru at idle on big displacement engines. VW did it on some carbs for other reasons. If the throttle plate is drilled, it may take some sleuthing on your part to figure what carb came on it originally and how the throttle plate was set up. Also make sure that the idle cut off solenoid circuit on the side has not been tampered with or leaking air.
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vwlover77
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Re: 34 PICT 3 Adjustment Woes

Post by vwlover77 » Tue May 09, 2017 11:50 am

All 34-PICT-3s have a hole in the throttle plate, do they not? Every one I've ever seen, including the one currently on the car, does.
Don

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78 Westy
71 Super Beetle Convertible Autostick

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Re: 34 PICT 3 Adjustment Woes

Post by asiab3 » Tue May 09, 2017 6:36 pm

Every one I have seen has the hole I vaguely remember the later SVDA 34pcit3 carbs having a slightly smaller hole from the factory.

Is the 950 idle in gear a new thing, or was it like that before? I just want to make sure we have our bases covered…

Robbie
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Re: 34 PICT 3 Adjustment Woes

Post by vwlover77 » Wed May 10, 2017 4:42 am

The current idle settings are nothing new, and basically where things were before I set the timing to 10 degrees ATDC and started this thread. The timing is now at what I believe to be the 5 degrees ATDC setting.
Don

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78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: 34 PICT 3 Adjustment Woes

Post by wcfvw69 » Wed May 10, 2017 6:15 am

The DVDA 34-3 carbs have a hole approx 5/32" where the SVDA's have one just shy of an 1/8".

VW 281-1 34PICT-3 113905205AH BUG 1600 1971 130 75z 60 USA Autostick
VW 281-2 34PICT-3 113908205AH BUG 1600 1972 127.5 75z 60 USA Autostick
VW 281-3 34PICT-3 113908205AH BUG 1600 1972 127.5 75z 55 California autostick
VW 281-4 34PICT-3 113908205AH BUG 1600 1973 127.5 75z 55 USA Autostick
Generator accelerator pump
VW 281-5 34PICT-3 1139008205AH BUG 1600 1973 127.5 75z USA Autostick
Alternator accelerator pump

A 1971 bug would have had a 113905205AH autostick DVDA installed when new as well. Have you verified what carb flange number and what distributor you have yet?
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: 34 PICT 3 Adjustment Woes

Post by vwlover77 » Wed May 10, 2017 8:30 am

The carb base is marked 281-2, so apparently it is not the original carb (the car was made in April '71). I had been running a 132.5 jet and changed it back to 130 just before staring this thread. I changed it back to the 132.5 as the car definitely runs better with it than the 130.

I probably won't get to the distributor until this weekend.
Don

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78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: 34 PICT 3 Adjustment Woes

Post by wcfvw69 » Wed May 10, 2017 8:11 pm

Well, the good news is you have an autostick German Solex 34-3. Now, let's hope you have the correct autostick Bosch DVDA distributor. :)
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: 34 PICT 3 Adjustment Woes

Post by Amskeptic » Fri May 12, 2017 6:50 pm

Don, I never never ever recommended a 10* ATDC timing specification for anything but a 1973-74 bus with DVDA and factory carbs. Only occasionally have I let slide a retarded idle specification BECAUSE WE TIMED THE ENGINE TO 28* @ 3,400 rpm, and the sloppy-a$$ distributor pulled it back too far and I said "WHO CARES? THE IMPORTANT THING IS THAT WE ARE CORRECT AT CRUISING SPEED."
So.
I ask you, "do you know what your timing is at 3,400 rpm?"
Colin
BobD - 1978 Bus . . . . . . . . . . .110,350 miles
Chloe - 1970 bus . . . . . . . . . . . 206,775 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles
Alexus - 1991 Lexus LS400 . . . 64,425 miles

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Re: 34 PICT 3 Adjustment Woes

Post by vwlover77 » Sat May 13, 2017 3:33 pm

You did not recommend 10* ATDC, that was my doing. In the old post on TS you did mention "If you shut the throttle, jack up the bypass air volume screw, retard the timing a smidge to keep your idle speed correct, or better yet, ensure that if you are supposed to have a vacuum retard with your set-up then make sure it is working, then your transition is fuelishly smooth. "

I guess 5 extra degrees of retard is more than a "smidge"!

https://www.thesamba.com/vw/forum/viewtopic.php?t=56411

Sadly, I do not know my timing at 3400 rpm. I do not have a timing scale pulley. What is the best way to measure this on a Type I engine?
Don

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71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: 34 PICT 3 Adjustment Woes

Post by asiab3 » Sun May 14, 2017 12:18 pm

vwlover77 wrote:
Sat May 13, 2017 3:33 pm
Sadly, I do not know my timing at 3400 rpm. I do not have a timing scale pulley. What is the best way to measure this on a Type I engine?
If you are 100% certain you know what your pulley markings are, I like to find a local degree pulley and hold it up next to yours and mark 28°, TDC, and BDC. This requires removing the rear breastplate to get it perfect, so most people take some masking tape on the outer circumference of a degree pulley, sharpie the numbers on, and then peel/stick the tape onto your stock pulley. The difference in circumference might be an issue, so I would only do this if the two pulleys were remarkably similar.

I can't stand the look of the aftermarket pulleys, which is why I like the "stock style degree pulley" I posted on the first page. It's the best of both worlds, and not as light-weight as the other aftermarket degree pulleys. (Which is good, as the weight balance is calculated into the harmonics of the crankshaft to match the #4 bearing size and flywheel "counterweight" on the other end.)

Or you could just get a timing light with built-in advance in it… :drunken:

Robbie
1969 bus, "Buddy"
http://theroadtells.com
"I would not do this again on a short time frame, the country is just so vast and beautiful…" - Barb/Elwood

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Re: 34 PICT 3 Adjustment Woes

Post by hambone » Sun May 14, 2017 3:45 pm

You can use a protractor and get pretty close.
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Re: 34 PICT 3 Adjustment Woes

Post by Amskeptic » Mon May 15, 2017 7:51 pm

I'd get a nice adjustable timing light with a built-in degree scale. You rev up the engine and turn the knob until you get your DIMPLE (the "0" designation) lined up with the crankcase edge. Read the number on the timing light knob. That is your timing.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,350 miles
Chloe - 1970 bus . . . . . . . . . . . 206,775 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles
Alexus - 1991 Lexus LS400 . . . 64,425 miles

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