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914World.com _ 914World Garage _ Giving Up On Vacuum Advance
Posted by: Ansbacher Jan 18 2019, 06:22 PM
Car = '74 2.0 Liter, Dual Dellorto Carbs
For years I have been 'adequately" running an 009 mechanical only distributor. Finally took the pervasive advice out there to go with a vacuum advance dizzy from a 1.8L 914. Since only one of my Dellorto carbs had an existing vacuum port (ported type), I had to drill a port in my other one (no problem there). I used good quality anti-pulse valves in the lines and measured a maximum vacuum of 12 inches of mercury with partial throttle.
Installed the 1.8 dizzy and set the timing, first without the vacuum lines attached. To satisfy my usual 30-32 degrees at 3500 RPM, the idle timing had to be at about 5-6 degrees (quite low for my setup which is happier at about 10 degrees. When I attached the vacuum lines my timing at 3500 RPM went sky high into the 40s. This seems way too high. Is this normal? Overall, I found the car to run better without the vacuum attached and the carbs plugged off.
Am I doing something wrong here? I don't like the numbers I am getting. Everyone said this was the way to go with carbs, but I am not seeing results. Advice appreciated.
Ansbacher
Posted by: nditiz1 Jan 18 2019, 11:11 PM
Ditch that distributor and get the correct one for vac adv. On that note the vac adv does not adv the timing at wot/3000+
The mechanical adv does that. Set to 10-12 idle 28-30 3000+.
Vac adv smooths out light throttle by over advancing to burn fuel more efficiently.
If you really want to scream install a 123distributor. Loved the one I ran on my 73 2.0 with carbs. It has vac adv too if you want to play around with it.
Posted by: pete000 Jan 19 2019, 01:15 AM
The 123 Dist is the way to go and no need for vac advance.
Posted by: Tbrown4x4 Jan 19 2019, 03:57 AM
I'll be watching this with interest. I'm going through a core 205 AA distributor right now. I wasn't planning on using the vacuum advance though. (1.7 with 40 IDA's)
If the total advance at 3500 rpm is really over 40, maybe you can install some kind of limiters to prevent the centrifugal from rotating the points plate that far. I agree about the vacuum advance not affecting total timing. I believe at 3500 rpm, the weights should be against their stops.
I also have an 009 in my car (installed by PO) that works OK, but was curious about other timing curves. I mean, can a distributor designed for a stationary engine really work well in a car?
Also, looking at a chart comparing 914 advance curves, I think the 1.8 just has a steeper curve that is shifted to a higher RPM range. Meaning it starts advancing later and is still advancing at a higher RPM.
Your timing numbers make sense because total advance = base timing + mechanical (at 3500 RPM).
I can put the stock 1.7 dizzy in, but the centrifugal can start as low as 700 RPM, and my idle speed is above that right now. I never worried about base timing because I just set the total at 3400 RPM and called it good. When I checked, the base timing was only 1 or 2 degrees. You should have smelled the exhaust!
Really eager to hear more opinions on this. A 123 Dist sound awesome, but certainly not in my budget.
Posted by: nditiz1 Jan 19 2019, 07:57 AM
I can't find the diagram right now, but someone posted the different distributors and curves. There are 2 or 3 I believe that can provide the curve you need which is a total mechanical advance of around 20 degrees (10 base + 20 full adv = 30 total timing at 3500)
Before using the 123 on my 2.0 I had the Mallory Unilite. It had swapable springs which you could change the spring rate and change the total adv.
While the 123 is costly at ~$450. You will never need another dist for your engine. The only other option is to source a used factory one or Mallory.
@http://www.914world.com/bbs2/index.php?showuser=17338 you are doing your setup an injustice by running that 009. If that 205 AA is listed as correct for your engine, get that cleaned up and working.
Posted by: BK911 Jan 19 2019, 08:17 AM
I've been running an 009 with carbs on a 1.7 for over 10 years now.
Car runs awesome.
If it ain't broke..........
Posted by: nditiz1 Jan 19 2019, 08:22 AM
I've been running an 009 with carbs on a 1.7 for over 10 years now.
Car runs awesome.
If it ain't broke..........
Just because you can run it doesn't mean you should
Posted by: tmessenger Jan 19 2019, 09:13 AM
SVDA 034 here's what they say for timing: Use a stroboscopic timing light. Timing should be set initially at 30-32° BTDC at 3,500+ RPM, vacuum hose disconnected and plugged. Maximum advance, at 3,500+ RPM, vacuum hose connected, with no load on engine (car sitting still), light throttle, should not exceed 42-44° BTDC.
Tim
Posted by: cgnj Jan 19 2019, 10:10 AM
How much vacuum @ idle? How much @ 3k?
7.5 degrees @ 800-900 rpm would be correct.
I think you are in the ballpark. High vacuum, low load you want to advance to increase mpg. The 10 degrees advance with the 009 is immaterial. It is compensation for the short curve.
Posted by: Ansbacher Jan 19 2019, 03:05 PM
How much vacuum @ idle? How much @ 3k?
7.5 degrees @ 800-900 rpm would be correct.
I think you are in the ballpark. High vacuum, low load you want to advance to increase mpg. The 10 degrees advance with the 009 is immaterial. It is compensation for the short curve.
Since I am using ported vacuum, I have 0 vacuum at idle. It doesn't kick in until the butterfly starts to open (as it should). At 3K I have 12 inches HG. The car is much more responsive on pull out when the idle timing is above 8 or so degrees. With this distributor I can't keep it under my target 32 degrees at 3500 RPM when I set idle to anything above 5 degrees, and that is WITHOUT vacuum hooked up. Add the vacuum and it really goes off the chart, I lose power, and it starts to ping when I tromp on it. This is my dilemma.
Ansbacher
Posted by: 914_teener Jan 19 2019, 04:14 PM
I went through a tremendous amount of effort to find decent parts for distributors.
I just bit the bullet and got a 123.
Going on two years and flawless. With the blue tooth app. no mo problems.
Posted by: pete000 Jan 19 2019, 04:35 PM
I love my blue tooth programmable 123 so easy and dead accurate. Set it and it is spot on, so tunable. Car never ran so good in its life!
Posted by: porschetub Jan 19 2019, 08:14 PM
My research indicated the anti pulse valve is only required if you only have one vacuum pickup,have you tried 2 vacuum lines from both carbs with a tee fitting to a single line on the distributor ?,the distributor will only advance to the range the vacuum unit was designed for so this seems strange you have this situation ,the advance place will only allow movement it its range also.
The so called SVDA used on 1600 beetles appears to work well on stock cam motors,and there is the Chinese repop which appears to be designed off the same unit,I have one of each and the repop one seems to be made well enough however don't think they will last as well as the originals 
.
Posted by: Mark Henry Jan 19 2019, 10:13 PM
Engine I just built for a customer, 914 2056cc with DTM for a bug.
Mallory unilight.
Attached image(s)
Posted by: Mark Henry Jan 20 2019, 09:42 AM
I've had a couple guys ask about the linkage, nice bit of kit.
https://www.thesamba.com/vw/classifieds/detail.php?id=2079800
Posted by: tmessenger Jan 20 2019, 09:50 AM
Mechanical advance springs fatigue with age, with weak springs the full mechanical advance comes to quickly at a lower RPM. Have you checked the curve to see if the mechanical advance is correct?
Tim
How much vacuum @ idle? How much @ 3k?
7.5 degrees @ 800-900 rpm would be correct.
I think you are in the ballpark. High vacuum, low load you want to advance to increase mpg. The 10 degrees advance with the 009 is immaterial. It is compensation for the short curve.
Since I am using ported vacuum, I have 0 vacuum at idle. It doesn't kick in until the butterfly starts to open (as it should). At 3K I have 12 inches HG. The car is much more responsive on pull out when the idle timing is above 8 or so degrees. With this distributor I can't keep it under my target 32 degrees at 3500 RPM when I set idle to anything above 5 degrees, and that is WITHOUT vacuum hooked up. Add the vacuum and it really goes off the chart, I lose power, and it starts to ping when I tromp on it. This is my dilemma.
Ansbacher
Posted by: Ansbacher Jan 20 2019, 11:33 AM
Answers to some questions posed of me:
Yes, I am using lines from BOTH carbs with a T-fitting to the vacuum pot. I have anti-pulse valves on BOTH lines in close proximity to the carbs. I tried a single valve but still got a pulse on the vacuum gauge. Using two, smoothed it out.
No, I have not checked the curve of the dizzy, and wouldn't know how to do it anyway. I am leaning toward the suggestion that I have worn out springs in the distributor. Is it hard to replace them?
Ansbacher
Posted by: r_towle Jan 20 2019, 07:44 PM
Based upon what is going on, and your last question, I would suggest you take out the advance plates, clean and re grease them.
It’s simple.
It costs about a nickle.
Needs to be done every 40 years 
http://www.914world.com/bbs2/index.php?showtopic=70988&hl=clean++distributor
Posted by: 72hardtop Jan 22 2019, 03:00 AM
Don't attempt to 'T' the lines together. Pull off (1) port only pref. #4 closest to the distributor. Put the anti pulse valve as close to the carb as possible (arrow points to carb).
T'ing the lines will increase pulsing and lower the overall signal greatly.
be sure the distributor is clean and greased properly (advance plate). Use Super lube.
You should have no additional vacuum advance at idle once the hose is hooked to the distributor. Set timing to roughly 28-30 degrees fully advanced ~3200rpm's (hose off plugged). Ideally you should be getting 7-10 degrees additional vacuum advance hose attached.
Blipping the throttle with a vac gauge should show the needle flicking to 8-10in.
Posted by: IronHillRestorations Jan 22 2019, 06:48 AM
One thing I forgot to mention is that the 1.8 distributor has an additional vacuum retard, and if you're connecting to the wrong vacuum port it will be a problem
Posted by: Ansbacher Jan 22 2019, 12:02 PM
Don't attempt to 'T' the lines together. Pull off (1) port only pref. #4 closest to the distributor. Put the anti pulse valve as close to the carb as possible (arrow points to carb).
T'ing the lines will increase pulsing and lower the overall signal greatly.
be sure the distributor is clean and greased properly (advance plate). Use Super lube.
You should have no additional vacuum advance at idle once the hose is hooked to the distributor. Set timing to roughly 28-30 degrees fully advanced ~3200rpm's (hose off plugged). Ideally you should be getting 7-10 degrees additional vacuum advance hose attached.
Blipping the throttle with a vac gauge should show the needle flicking to 8-10in.
With this distributor, there is no way I can set timing to 28-30 degrees. If I do, it puts my idle timing at 0 degrees or less, making it impossible to run good at idle. Also, I found that T-ing the lines from both carbs smoothed the vacuum out.
Ansbacher
Posted by: 72hardtop Jan 22 2019, 01:15 PM
Don't attempt to 'T' the lines together. Pull off (1) port only pref. #4 closest to the distributor. Put the anti pulse valve as close to the carb as possible (arrow points to carb).
T'ing the lines will increase pulsing and lower the overall signal greatly.
be sure the distributor is clean and greased properly (advance plate). Use Super lube.
You should have no additional vacuum advance at idle once the hose is hooked to the distributor. Set timing to roughly 28-30 degrees fully advanced ~3200rpm's (hose off plugged). Ideally you should be getting 7-10 degrees additional vacuum advance hose attached.
Blipping the throttle with a vac gauge should show the needle flicking to 8-10in.
With this distributor, there is no way I can set timing to 28-30 degrees. If I do, it puts my idle timing at 0 degrees or less, making it impossible to run good at idle. Also, I found that T-ing the lines from both carbs smoothed the vacuum out.
Ansbacher
You need to limit the advance (tweak the stops) the Type-4 loves some initial advance roughly 10-12 initial. You only need 1 vac line.
The additional advance (vac advance) will be load sensed. Load being throttle position. Get a bung welded in and start tuning with an LM-2.
Part throttle....16-17 AFR
WOT....12.5 - 13.2 or so
Posted by: Red72 Jan 28 2019, 11:21 AM
Jumping in here, and I'm sorry to hijack it somewhat, but this seems to at least be an active dizzy thread.
I'm fairly new to distributors, and I'm looking to tweak the curve with the springs and stops on my pertronix unit on my 1.7l engine. I'm looking to combine two different spring weights in order to control the initial (off idle), and total advance. The question I have is, will I still get full advance if I limit the advance on a LIGHT spring to something like 6 degrees above initial, and then allow the HEAVY spring to go all the way to 20 degrees advance, resulting in something like 28 full advance?
Thinking that this will bring advance on early, but then climb more slowly up to 3500rpm. This seems to more closely match the curves of non-vacuum, non-009 units.
I realize the answer here seems to be 'get the 123 unit', but the dollars for that isn't in the cards right now.
Thanks.
Posted by: tmessenger Jan 28 2019, 12:40 PM
I went through this with a Triumph TR3 a couple of years ago, the factory distributor springs were NA and the old springs were shot. I modified other springs to work and it was just a process of trial and error to get the curve right. I used an electronic inductive tachometer to dial in different engine speeds and then checked the advance at the crank with a timing light. It took a while but I tweaked the springs until the mechanical advance curve was correct.
The only other option I know of is to find someone that has an old sun distributor machine to set up the mechanical advance.
Tim
Jumping in here, and I'm sorry to hijack it somewhat, but this seems to at least be an active dizzy thread.
I'm fairly new to distributors, and I'm looking to tweak the curve with the springs and stops on my pertronix unit on my 1.7l engine. I'm looking to combine two different spring weights in order to control the initial (off idle), and total advance. The question I have is, will I still get full advance if I limit the advance on a LIGHT spring to something like 6 degrees above initial, and then allow the HEAVY spring to go all the way to 20 degrees advance, resulting in something like 28 full advance?
Thinking that this will bring advance on early, but then climb more slowly up to 3500rpm. This seems to more closely match the curves of non-vacuum, non-009 units.
I realize the answer here seems to be 'get the 123 unit', but the dollars for that isn't in the cards right now.
Thanks.
Posted by: Rand Jan 28 2019, 02:16 PM
I've been running an 009 with carbs on a 1.7 for over 10 years now.
Car runs awesome.
If it ain't broke..........
I love that yours runs awesome. But can you imagine a tuning that would bring another 20hp with the same mileage? I bet Joe Sharp could.
Back on topic, should he use vacuum advance or retard? I found it to be differential because of difference years, dizzyy's, etc.
I had one experience where the retard wasn't working and it made my idle high. Fixed with a part replacement. Carbs will be always suck when you get out of your optimum altitude. FI adjusts as needed. Is there really a need to keep debating it?
.
Posted by: 72hardtop Jan 28 2019, 08:52 PM
I've been running an 009 with carbs on a 1.7 for over 10 years now.
Car runs awesome.
If it ain't broke..........
I love that yours runs awesome. But can you imagine a tuning that would bring another 20hp with the same mileage? I bet Joe Sharp could.
Back on topic, should he use vacuum advance or retard? I found it to be differential because of difference years, dizzyy's, etc.
I had one experience where the retard wasn't working and it made my idle high. Fixed with a part replacement. Carbs will be always suck when you get out of your optimum altitude. FI adjusts as needed. Is there really a need to keep debating it?
.
Not a debate with an EFI system. But unless one is traveling between altitudes on a regular basis (most aren't). I prefer a dual set up. More horsepower. If one is going EFI go with a modern set up not the stock one.
Posted by: Rand Jan 28 2019, 09:05 PM
Did you just suggest that you can create so much horsepower in a slim sliver of a band (whichI will argue) that you are actually suggesting carbs are better? Ignoring altitudes (which is only one of the many huge side benefits of FI and why NO car comes carbs anymore)
The stock one. Still better than carbs? Which were implemented and when? Stone wheels also have the best traction.
Posted by: Rand Jan 28 2019, 09:21 PM
Let me take this second to say that I respect Joe Sharp. And he sure as hell knows how to tune carbs.
Anything I said above that sounded like I hated carbs should be re-looked at from where I was coming from.
JoeS actually offered get me a six running years ago. Thank you.
The point of my post is not to stir anything up more than thought.
I don't hate carb. It's just freaking obvious that FI is more efficient than carbs proven for decades. I LOVE the sound of carbs. I got no dog in the fight. It's just conversation. When those carb throttle bodies open full, we all go silent to listen. 
Posted by: MarkV Jan 28 2019, 09:22 PM
No doubt fuel injection is better. Many of us have carburetors and prefer them even though injection is superior. The stock injection doesn't allow for much in the way of engine modification.
I think the OP's question was about dual carbs and vacuum advance.
If you can find an old Mallory distributor they have an advance mechanism that is easily adjusted without having to use a distributor machine. 
Posted by: 72hardtop Jan 29 2019, 02:42 PM
Did you just suggest that you can create so much horsepower in a slim sliver of a band (whichI will argue) that you are actually suggesting carbs are better? Ignoring altitudes (which is only one of the many huge side benefits of FI and why NO car comes carbs anymore)
The stock one. Still better than carbs? Which were implemented and when? Stone wheels also have the best traction.
The stock EFI systems have many parts that are NLA. Which is why if you go EFI go modern. As for a dual set up....if properly jetted you'll create more horsepower then an EFI set up.
Ive tuned my Weber 40's in my 2056 T-4 hardtop bus and get better MPG's than the stock Type 4 powered buses with stock fuel injection.
Cold start drive-ability is probably the best thing about an EFI set up.
Posted by: 914_teener Jan 29 2019, 04:30 PM
Ok....I'm an EFI guy so for carbs it's the way back machine for me.
So, stupid question (mine) with your first post and subsequent ones in mind...forget about EFI better or not.
Stupid question:
When you say you are using "ported" vacuum, where in relationship to the throttle plate is that that port, look at a side view of the carb?
Posted by: 914_teener Jan 29 2019, 04:49 PM
https://web.archive.org/web/20001007043902/http://www.dgi.net/914/tech/distrib.html
Thread on the Bird Board a while back that Dave Darling wrote.
Went through this myself when I was trying to match a stock dizzy to an EFI system. I finally got tired...from a time perspective and went with the 123.
It is important as to where the port vaccum is in relationship to the throttle plate.
So manifold port? Carb port? Below the Throttle plate or above it?
Take a picture and post it.
Posted by: 72hardtop Jan 29 2019, 05:04 PM
Ok....I'm an EFI guy so for carbs it's the way back machine for me.
So, stupid question (mine) with your first post and subsequent ones in mind...forget about EFI better or not.
Stupid question:
When you say you are using "ported" vacuum, where in relationship to the throttle plate is that that port, look at a side view of the carb?
Above the throttle plate. You should have zero vacuum with the throttle closed.
Posted by: 914_teener Jan 29 2019, 06:49 PM
Well then another dumb bunch of questions:
Isn't the vacuum below the throttle plate manifold vacuum and not "ported" vacuum?
At part load or idle you want it above the plate not below IIRC.
So static timing set...then as the TP opens vacuum increases to the point where they equalize and the mechanical takes over. Isn't this is how it is supposed to work?
I dont' remember.
Next dumb question:
Is the diaphragm tested as working?
Next:
Is the AFM right? Too lean....slow....too rich fast.
Posted by: 72hardtop Jan 30 2019, 10:46 PM
Corrected. Got ahead of myself there. Ported vac always with a distributor vac advance.
Distributor on mine is fairly new (Bosch SVDA). Used an LM-2 for jetting.
Posted by: tmessenger Jan 31 2019, 08:23 AM
Ported vacuum with vac port covered by the throttle plate at idle, connect in your vacuum gauge and check that you have no vac at idle.
Jake Raby likes to set up carbs at a/f 13:1 throughout so a bit different than the lean burn under light loads that John at aircooled.net aspires to.
Note: this is a heavy read.
The mother of all carb tuning threads (including timing theory) is on the samba here:
https://www.thesamba.com/vw/forum/viewtopic.php?t=293837&postdays=0&postorder=asc&start=0&sid=477b2b68fd1da7846c74c2cf44f55a21
Good luck,
Tim
Corrected. Got ahead of myself there. Ported vac always with a distributor vac advance.
Distributor on mine is fairly new (Bosch SVDA). Used an LM-2 for jetting.
Posted by: cgnj Jan 31 2019, 08:31 PM
Ported vacuum with vac port covered by the throttle plate at idle, connect in your vacuum gauge and check that you have no vac at idle.
Jake Raby likes to set up carbs at a/f 13:1 throughout so a bit different than the lean burn under light loads that John at aircooled.net aspires to.
Note: this is a heavy read.
The mother of all carb tuning threads (including timing theory) is on the samba here:
https://www.thesamba.com/vw/forum/viewtopic.php?t=293837&postdays=0&postorder=asc&start=0&sid=477b2b68fd1da7846c74c2cf44f55a21
Good luck,
Tim
Corrected. Got ahead of myself there. Ported vac always with a distributor vac advance.
Distributor on mine is fairly new (Bosch SVDA). Used an LM-2 for jetting.
]Good link Tim, going to take a week to read it all (99 pages). I find myself drawn to the "we tune carbs/timing with the wrong approach".
Posted by: tmessenger Jan 31 2019, 10:06 PM
There are 11 years of knowledge in those 99 pages. I started with it about a week ago and I'm now on page 85. If your engine is mechanically healthy to start with you'll be way ahead of the curve when it comes time to solve carb tune and timing issues with this knowledge.
Do yourself a favor and copy and past the basic concepts into a word doc as you go and anything else that is relevant to you. I went through the first 20 pages and then the light went off and ding I had to backtracked to collect the gold into a condensed version for future reference.
You're also going to need one of these or something like it if you don't already have one:
https://www.14point7.com/products/sigma-lambda-controller-free-2
Tim
[quote name='72hardtop' post='2685043' date='Jan 30 2019, 10:46 PM']
Corrected. Got ahead of myself there. Ported vac always with a distributor vac advance.
Distributor on mine is fairly new (Bosch SVDA). Used an LM-2 for jetting.
[/quote]
[/quote]
]Good link Tim, going to take a week to read it all (99 pages). I find myself drawn to the "we tune carbs/timing with the wrong approach".
[/quote]
Posted by: 72hardtop Jan 31 2019, 11:18 PM
You can garner a lot from that thread with the first 20 pages alone.
Remember....
Get above 14:0 - 15:5 on the progression circuit and below it (14:0 - 15:5) when on the main jets. Ideally when under load/WOT... 12:5-13:2 or so. 14:0 -15:5 is the highest area for EGT's.
Load = Throttle position
No lean tune cruising with mechanical only distributors.
Posted by: tmessenger Feb 1 2019, 01:28 PM
72hardtop
Sounds like we have very similar engine builds, mine is:
Fat Performance built 2056 long block, 42x38 ported and polished heads, Fat 442 cam, 8.3 : 1 compression 4k miles on the build.
I just bought this car 6 weeks ago so am just now starting with the carb tune. The current configuration I inherited :
40 IDF Webers, 32mm venturi's, 60 idle jets, 135 mains, F11 emulsion tubes, 175 air's, SVDA distributor with stock 2.0 heat exchanges and Triad muffler.
I've just ordered an A/F gauge to start the process.
Can you tell me how your finalized carbs jetting came out and your A/F readings? Could be useful to both of us to compare notes.
Thanks, Tim
You can garner a lot from that thread with the first 20 pages alone.
Remember....
Get above 14:0 - 15:5 on the progression circuit and below it (14:0 - 15:5) when on the main jets. Ideally when under load/WOT... 12:5-13:2 or so. 14:0 -15:5 is the highest area for EGT's.
Load = Throttle position
No lean tune cruising with mechanical only distributors.
Posted by: 72hardtop May 8 2019, 03:47 PM
72hardtop
Sounds like we have very similar engine builds, mine is:
Fat Performance built 2056 long block, 42x38 ported and polished heads, Fat 442 cam, 8.3 : 1 compression 4k miles on the build.
I just bought this car 6 weeks ago so am just now starting with the carb tune. The current configuration I inherited :
40 IDF Webers, 32mm venturi's, 60 idle jets, 135 mains, F11 emulsion tubes, 175 air's, SVDA distributor with stock 2.0 heat exchanges and Triad muffler.
I've just ordered an A/F gauge to start the process.
Can you tell me how your finalized carbs jetting came out and your A/F readings? Could be useful to both of us to compare notes.
Thanks, Tim
You can garner a lot from that thread with the first 20 pages alone.
Remember....
Get above 14:0 - 15:5 on the progression circuit and below it (14:0 - 15:5) when on the main jets. Ideally when under load/WOT... 12:5-13:2 or so. 14:0 -15:5 is the highest area for EGT's.
Load = Throttle position
No lean tune cruising with mechanical only distributors.
Final jetting on mine....
47.5 idles
125 mains
210 air correctors
F11 Tubes
28mm vents
At light/part throttle the AFR hovers 14.X - low 17.X (light load conditions)
WOT - 12.X - low 13's
Timing is 28 BTDC @ 3200rpm's (hose off/plugged) SVDA
Elevation here is roughly 525 feet above sea level
Posted by: 72hardtop May 8 2019, 03:54 PM
Ported vacuum with vac port covered by the throttle plate at idle, connect in your vacuum gauge and check that you have no vac at idle.
Jake Raby likes to set up carbs at a/f 13:1 throughout so a bit different than the lean burn under light loads that John at aircooled.net aspires to.
Note: this is a heavy read.
The mother of all carb tuning threads (including timing theory) is on the samba here:
https://www.thesamba.com/vw/forum/viewtopic.php?t=293837&postdays=0&postorder=asc&start=0&sid=477b2b68fd1da7846c74c2cf44f55a21
Good luck,
Tim
Corrected. Got ahead of myself there. Ported vac always with a distributor vac advance.
Distributor on mine is fairly new (Bosch SVDA). Used an LM-2 for jetting.
Setting IDF's to 13:1 across the board would require reaming of idle jets. Standard Weber jets wont suffice. If I were shooting for power and coolness....13:1 would be where I'd want to be. But you won't see decent MPG's with that during part throttle condition.
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