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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16886
Location: sticksville, ct.
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 Posted: Tue Feb 26, 2019 8:12 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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I'm betting theirs was a "take off" seeing that they were sold as individual pieces.
I have a NOS one I would LOVE to get off of my shelf if anyone is interested
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| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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D/A/N
Samba Member
Joined: August 13, 2010
Posts: 2227
Location: 11222
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D/A/N
Samba Member
Joined: August 13, 2010
Posts: 2227
Location: 11222
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| Posted: Fri Mar 08, 2019 6:59 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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| D/A/N wrote: |
| skills@eurocarsplus wrote: |
I'm betting theirs was a "take off" seeing that they were sold as individual pieces.
I have a NOS one I would LOVE to get off of my shelf if anyone is interested |
PM me! |
Ok....so it's been a few weeks since I updated this, but I got the NOS part from skills and it looks great.
Otherwise, we've been adjusting our current positioner bit by bit. We're now at the point that the throttle hangs open for about 4 seconds after coming to a stop. Clearly, we need a bit more adjustment, but things are better overall. Of course our set screw has now frozen in the "un-set" position so until we pull the part and free that up, the adjustment screw is liable to wander. We've yet to adjust anything but the large screw on the positioner.
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'69 Fuel Injected Squareback. "B" D-jet. 1600 with balanced rotating assembly and lightened flywheel. Full flow and external filter.
'70 Riviera. 1904cc w/ 40mm Dellortos, 019 distributor, Steve Tims “super stock” 37x32 heads, Web Cam 218, Vintage Speed SS143 Super Speed exhaust, 1 1/2” heater boxes |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16886
Location: sticksville, ct.
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| Posted: Fri Mar 08, 2019 7:01 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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hopefully it serves you well. and I will give you full credit on it should you decide to go Subaru power 
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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ccowx
Samba Member
Joined: May 15, 2015
Posts: 661
Location: Whitehorse Yukon
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| Posted: Sun Mar 10, 2019 8:35 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Very useful thread indeed, thanks for the time, gentlemen! One question though. I am not seeing how the two piece set up is plumbed with vacuum lines. I see that one hose goes to the intake and one to the angled fitting on the carb.
What I can not figure out is how the "altitude corrector" on the driver's side of the engine bay is hooked into the system. It obviously has a vacuum port but where does that connect? I am quite sure I will feel stupid when I see the answer!
Thanks!
Chris
PS: The vehicle will be a 70 Westfalia with a dual port and a PICT 34-3 |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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| Posted: Sun Mar 10, 2019 9:28 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Hi Chris, thanks for the kind words.
The 70 (CA) -71 two-piece altitude adjuster (with the brass screw) on the left side of the engine compartment gets a 5mm vacuum line to the intake manifold, and a 3.5mm vacuum line to the angled port on the pict3 carburetors. There are two nipples on the altitude adjuster. Look carefully!
68-69 (and 70 federal) one-piece positioners had one short 5mm vacuum line to the intake manifold, usually close to the carb base.
Robbie
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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Mon Mar 11, 2019 7:57 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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here is an earlier Robbie post.
| asiab3 wrote: |
“What is this thing? Do I need it?”
The throttle positioner. Yes.
Photo courtesy of wcfvw69.
Background:
In 1967 (model year 1968 for our Volkswagens) the Federal Air Quality Act was enacted. In addition to allowing California to set its own stricter emissions regulations, due to its larger pollution base, it amended the 1963 Clean Air Act and focused on regional issues and stationary power produced emissions.
From www.arb.ca.gov:
| Quote: |
| Federal Air Quality Act of 1967 was enacted. It established a framework for defining "air quality control regions" based on meteorological and topographical factors of air pollution. |
http://www.arb.ca.gov/html/brochure/history.htm - accessed 11/1/15
However, the 1967 act did not go far enough, as the public did not feel the pace of improvement was acceptable. Enter the Clean Air Act of 1970, (1971 model years for us,) which moved far more aggressively to limit emissions of mobile sources. (Remember, Volkswagens were still new then, so they were in fact mobile! …since no one was using them as chicken coops yet.) The Environmental Protection Agency was also founded this year, along with the holding of the first Earth Day, on April 22nd, 1970. What kick started this year’s movement, was the signing of the National Environmental Policy Act. This is considered by scholars to be the “environmental Magna Carta.”
Raw gasoline practically belches hydrocarbons, which can combine with other gases to create a majority of smog-based health hazards. I am not a chemist, so I will not attempt to explain the course of chemical evils, but just remember that more than 99% of pollutant gases are invisible.
What it does, and how it works:
The air required to run an internal combustion engine must flow through the carb in such a way that it draws in just enough fuel for a complete burn. However, we know that different engine conditions require different mixtures, so carburetor technology has changed over time to allow the proportional mixing of air and fuel when the engine requires it. When the engine does not require much air and fuel, like when you release the pedal and the engine returns to idle, carburetors are extremely ineffective and inaccurate at mixing air and fuel.
When a piston goes down and “sucks” in intake air and fuel in, it creates negative pressure in the intake known as “vacuum.” The level of vacuum is dependent on engine speed, (how fast the cylinders are pulling air in,) and throttle position, (how much air volume is allowed in due to suction.) Imagine that you are traveling at a high RPM on the freeway, and you let of the pedal immediately because you were hastily cut off by a Prius driver who looks at the fuel economy gauge instead of the speedometer. “But it says 65!” The pistons are sucking air mightily, and the throttle plate is trying to cut off airflow, so the vacuum, or suction level, in the intact tract is extremely high. This creates a sudden influx in fuel, because of the sudden increase in air suction. But your Volkswagen doesn’t need the fuel!
Enter the throttle positioner. By using a mechanical linkage to detect these spikes in intake vacuum, the throttle positioner actually holds your throttle arm and throttle plate open a tiny bit while the engine slows down. This reduces the fuel dumped needlessly through the engine, preventing raw gas from fizzling out your tailpipe.
The mechanical aspect of the linkage is simple. There is a vacuum diaphragm inside the positioner arm, and when your intake manifold vacuum is high enough, it pulls the arm. Just like a distributor vacuum advance can. The amount of vacuum produced by the engine depends on many factors, like age, wear, cam profile, and timing, so adjustments can be made. Inside the assembly underneath the brass screw is a bellows that can compensate for vacuum changes. Bentley calls this the “altitude adjuster,” as vacuum levels greatly change with “elevation.”
Differences in models:
1968-1969 model year bugs and buses came with the one piece style positioner, which includes the actuating arm/diaphragm and adjustment screw/bellows in one housing. The one-piece throttle positioner mounts directly underneath the carburetor, and requires an additional gasket to the intake manifold. There is only one vacuum port, and it receives full manifold vacuum from a nipple on the intake manifold.
An example of a correctly functioning one-piece throttle positioner can be seen here, courtesy of wcfvw69:
Link
1970-1971 model year bugs and buses came with the two-piece style throttle positioner, which functions almost identically, but is split into two pieces. The two-piece unit has two vacuum hoses as well; one hose goes to an intake manifold vacuum port, but now the other hose goes to a new vacuum nipple on the 30pict3 and 34pict3 carburetors.
The actuating arm is still mounted to the carburetor, except now it looks like this:
The adjusting part is now located on the left side of the engine bay, in both bugs and buses.
Photo courtesy of busdaddy.
Photo courtesy of celticbob.
What else it does/alternate names:
The throttle positioner can also be called the shift enhancer, smog device, ride smoother-outer, backfire eliminator, and my personal favorite, unnecessary. It is all but one of those things.
By slowing down the throttle plate return on a carburetor, the engine stays at a slightly higher RPM when you upshift. This creates a smoother transition into the next gear, creating greater comfort and pleasure for drivers and passengers alike, IF you care about such things. This also matches the transaxle input shaft speed more closely to that which is required for the next gear. This puts vastly less wear on your synchronizers in the transaxle, and you SHOULD care about that.
We’ve already discussed how it can avoid dumping the gas out the tailpipe for emissions reasons, but does your car gurgle and fart on long downhills with the throttle shut? The throttle positioner purifies the air/fuel mixture on throttle overrun, so these little queefs of the car will be reduced or eliminated as well. Unless you have an exhaust leak. Get that shit fixed.
Installation and adjustment:
As a general rule, your car can use the one-piece throttle positioner if you have a vacuum port below the carburetor mounting flange on the intake manifold. As the second general rule, you can use the two piece throttle positioner if your carburetor has the angled vacuum port on the right side, (shown here in red,) AND a similar vacuum port on the intake.
It is worth paying special attention to the mounting brackets, regardless of which type of throttle positioner you choose to install. The 34pic4 carburetor has a larger base flange, so it requires the 1971 one-year-only mounting bracket. All other carburetors interchange mounting brackets. In addition, both the one-piece and two-piece positioner use the same “ring mount” style, so you can mix and match parts to get a mount and a positioner that works with your setup.
With the one-piece positioner, the factory provided a vacuum port just below the carburetor flange for your hose to reach. Since parts get swapped and all three of us that care about throttle positioners can’t be evangelical enough, your vacuum port may be on the left side of the intake down pipe, or on the far left by the cylinder head part of the manifold.
With the two-piece positioner, the angled carburetor port is always near the diaphragm connection, and the factory vacuum port for the second connection is on the left side of single port manifolds, and cast into the #3&4 end piece of the dual port intake manifold. Regardless of where your hoses end up, notice how the two ports are of different sizes? Standard distributor vacuum hose works for the smaller size, and 5mm (fuel hose size) vacuum hose works for the larger connection.
Adjusting the throttle positioner is detailed quite thoroughly in Bentley. Whaaaat you thought I was going to spoon feed it to you? HA! I will say your carburetor needs the secondary throttle arm to attach the mechanism to; without it you're out of luck.
Final thoughts:
Your car will run without the throttle positioner. Most take it off and throw it away, but some sell them to me for a couple bucks. I have enough spare to last my lifetime, so now it is time for you, good reader, to peruse the classifieds and junk yards of the world and get your engine working like it is supposed to.
wcfvw69 has a thorough article on rebuilding the one-piece positioner. The two-piece positioner will be rebuilt the same. Usually, I see two-piece positioners need nothing but a cleaning and one-piece positioners needing a diaphragm of some kind. Nitrile sheet gasket would be ok, but viton would be best for recreating the diaphragms using the old ripped ones as templates.
http://www.thesamba.com/vw/forum/viewtopic.php?t=637886
Remember how I said the two types function almost identically? Since I am feeling tired of typing, I will offer a prize to anybody who can tell me WHY Volkswagen went to a two-piece system. Answer in complete sentences, and perhaps explain the major functional improvement please. 
Love and good air quality,
Robbie |
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ccowx
Samba Member
Joined: May 15, 2015
Posts: 661
Location: Whitehorse Yukon
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| Posted: Sat Mar 16, 2019 8:31 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Thanks guys for taking the time to so throoughly explain this thing! This is the kind of factory engineering that gets tossed and people never understand what they actually did.
I am probably going to try to get this system functional again. I am currently putting a 1970 Westfalia together and the plan engine wise is to improve both power and driveability from the mismatched combination in there now. I am adding headers and a different cam and enlarging the venturi in the 34-3 for added power. However, I am also making sure that all of the factory systems such as carb air and manifold pre-heat, vac advance, etc are all working correctly. These systems will need to be recalibrated or adjusted to work properly with the new engine specs. Some will need modifications, such as the correct flow through on the manifold heat or improving the carb air pre-heat to pick up heat directly from the headers. The throttle positioner sounds like another way to improve this engine and make it more pleasant to drive without compromising other areas.
My goal overall is to achieve a blend of efficiency, power and driveability. Thanks for the help!
Chris |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
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| Posted: Sat Mar 16, 2019 4:51 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Hey Chris,
I've found the altitude adjustment on the throttle positioners to be VERY responsive to adjustment. I don't think you'll have a problem getting a stock setup to play nicely with your setup. Our moderator Brian had a single-piece positioner on his 2-liter Type 1 with "34"pict3 carb (enlarged internals) just like you're planning. We installed and tuned his at a car show eating pizza surrounded by BMW kids wondering what those shiny things in our hands that said "Snap On" were.
Make sure your intake manifold has the vacuum nipple on the left side if you go two-piece (correct for 1970) or vacuum nipple on the vertical section of the manifold, if you go one-piece. The 34pict3 (1971) used a one-year-only throttle positioner mount to fit the base section of the 34pict carburetors. Be sure you have that base and the correct linkage end to fit your carb arm. (Clevis pin style and ball/socket style are common.)
See you on the road,
Robbie
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Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
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ccowx
Samba Member
Joined: May 15, 2015
Posts: 661
Location: Whitehorse Yukon
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| Posted: Sat Mar 16, 2019 5:01 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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I have two of the units that attach to the driver side of the engine bay and have the adjustor screw in it. The PICT 34-3 I have has the angled fitting (red in the illustrations) and I have an end casting for the DP intake that has the vac fitting. What I will need to find is the unit that goes on the carb itself and it's mounting bracket, plus the arm on the carb linkage.
Thanks again!
Chris
PS: If anyone has the correct bracket or part, feel free to let me know! |
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skills@eurocarsplus
Samba Peckerhead
Joined: January 01, 2007
Posts: 16886
Location: sticksville, ct.
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| Posted: Sat Mar 16, 2019 5:05 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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| asiab3 wrote: |
| BMW kids wondering what those shiny things in our hands that said "Snap On" were. |
did you tell them that those shiny things belong to a guy named gary with a street name of "aeromech"?
side note: I would rather hang with the bmw kids...they spend $$ like it's not theirs
_________________
| gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
| Jake Raby wrote: |
| Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
| Brian wrote: |
| Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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ccowx
Samba Member
Joined: May 15, 2015
Posts: 661
Location: Whitehorse Yukon
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| Posted: Sat Mar 16, 2019 5:20 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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| It's not theirs, it is their parents. Unless they are drug dealers. |
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D/A/N
Samba Member
Joined: August 13, 2010
Posts: 2227
Location: 11222
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| Posted: Sat Jun 22, 2019 4:53 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Okay, so I last posted in here about 4 months ago about some issues with our two-piece throttle positioner. Those went away with a bit of careful adjusting. Now, we're having a different issue.
Symptoms: We recently had the motor out but didn't touch the throttle positioner other than to remove the vacuum lines and when we removed the carb. Now, once the choke is off, the idle won't drop below 1500 rpms unless the vacuum line is pulled off the left nipple of the piece that fits below the carb. We noticed this as soon as we started up the motor after re-installing. Prior to this, all was well. I tried to dial back the adjustment but it had no effect on the idle speed.
Today, we (me, neena, and sjbartnik) opened up the adjustable portion thinking that my abrupt adjustments might have torn the diaphragm. The diaphragm is indeed torn up
We bought a NOS one piece adjuster from skills and we replaced our diaphragm and adjusting screw unit with the NOS one. Still no adjustment is possible. The throttle just hangs open. We pulled the vac line off the manifold and plugged it up. No difference. It seems like we've eliminated everything from the left of the engine bay from the problem yet we still have a problem.
It seems like the issue must be in the piece beneath the carb, but what the hell is in there? We loosened the screws on the front of it, but the halves seem crimped together. Is there a diaphragm in there that can take a dump?
The only way the motor runs correctly is with the left vac line disconnected and the nipple open to the atmosphere. Even just covering it up with a finger or thumb will cause the throttle to open up. There's a video below that shows what I'm talking about
Any ideas about what we should do next?
Link
_________________
'69 Fuel Injected Squareback. "B" D-jet. 1600 with balanced rotating assembly and lightened flywheel. Full flow and external filter.
'70 Riviera. 1904cc w/ 40mm Dellortos, 019 distributor, Steve Tims “super stock” 37x32 heads, Web Cam 218, Vintage Speed SS143 Super Speed exhaust, 1 1/2” heater boxes |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Sat Jun 22, 2019 4:57 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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usually when it hangs it is because the delay is set too high. If changing the screw doesn't cause it to drop, make sure that the cable is not too tight, and that the dashpot is you have one is not sticking.
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22670
Location: NYC/Upstate/ROW
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| Posted: Sat Jun 22, 2019 5:56 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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I think you have the hose on the wrong port, constant vacuum at idle isn’t right.
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D/A/N
Samba Member
Joined: August 13, 2010
Posts: 2227
Location: 11222
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| Posted: Sat Jun 22, 2019 6:06 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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| Abscate wrote: |
| I think you have the hose on the wrong port, constant vacuum at idle isn’t right. |
The hoses are on the same ports they were on when everything worked, I promise!
What you say makes me think there's an issue with the diaphragm in the piece that mounts under the carb. Since we eliminated the dashpot part that mounts on the left side of the engine bay and the issue still persists, what else is there if the hoses are also correctly mounted?
_________________
'69 Fuel Injected Squareback. "B" D-jet. 1600 with balanced rotating assembly and lightened flywheel. Full flow and external filter.
'70 Riviera. 1904cc w/ 40mm Dellortos, 019 distributor, Steve Tims “super stock” 37x32 heads, Web Cam 218, Vintage Speed SS143 Super Speed exhaust, 1 1/2” heater boxes |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Sat Jun 22, 2019 7:11 pm Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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See photos to see if you have it right. If you do the issue might be the TP on the left side of the engine bay.
The large hose on the TP goes to the manifold as I recall and the small one to the other side of the TP.
Both photos are from threads here at the Samba.
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22670
Location: NYC/Upstate/ROW
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| Posted: Sun Jun 23, 2019 1:07 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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| skills@eurocarsplus wrote: |
| asiab3 wrote: |
| BMW kids wondering what those shiny things in our hands that said "Snap On" were. |
did you tell them that those shiny things belong to a guy named gary with a street name of "aeromech"?
side note: I would rather hang with the bmw kids...they spend $$ like it's not theirs |
4 hour minimium to register a BMW battery, plus shop supplies.
Back OT, Dan....your video showing throttle moving at idle when you cover up the port to the two piece altitude positioner is showing there is too much vacuum on the carb port at idle, I think. Maybe Robbie can measure his and document ? That has to be something. Wrong internal to the carb , I think
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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Sun Jun 23, 2019 8:13 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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Their throttle positioner is definitely connected correctly as shown in the photos above.
I did note that when I pulled off the hose that connects to the carb and put my thumb over the vacuum port on the carb, I did not feel any suction at idle.
That was in contrast to when I pulled the large vacuum hose from the manifold off the throttle positioner and put my thumb over it, I could quite easily feel the suction.
I was just thinking about it this morning; if the vacuum port on the carb somehow got blocked (by base gasket or with sealer or something) would that cause the issue? It seems to me (with my admittedly limited understanding of the system) that if you had no vacuum signal from the carb and full vacuum signal from the positioner that might cause the diaphragm at the carb to move the pull rod and hold the throttle open.
I would be interested to put a vacuum gauge on that carb fitting and see what the reading is. Maybe it’s fine and the vacuum is just too minuscule to feel via thumb gauge. 
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Sun Jun 23, 2019 9:44 am Post subject: Re: Throttle positioner, Control valve with High altitude corrector! |
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1) make sure that the butter fly is closing to spec at idle. If vacuum is getting past it at idle you might have a situation where that vacuum is opening the valve.
I don't have a 1971 anymore to test on, but does applying a vacuum to the left side close it or open it?
Also, you didn't take that carb TP valve apart and accidentally rotate it 180 degrees by chance when you were working on it?
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