We’ve had a bunch of wiring, tuning and general maintenance questions lately and I’d thought it would be good to pass along some helpful technical links
Good clear images to print out and put into your repair manuals.
Technical Source links (good to bookmark and browse on a rainy day)

http://www.oldvolkshome.com/
http://www.aircooledtech.com/
http://www.thesamba.com/vw/archives/info/
http://www.geneberg.com/techtips.php
http://www.type2.com/library/library.htm
http://www.ratwell.com/
http://www.vw-resource.com/table.html
http://www.aircooled.net/vw-technical-articles/
http://www.magmaweb.com/vwmarketplace/tech.html
http://www.airheadparts.com/tech
http://thegoldenbug.com/en/vw_technical_articles
http://www.chircoestore.com/catalog/articles.php

All Articles (106)
Engine Build Pages (11)
Tech - Basic Info (4)
Tech - Braking System (1)
Tech - Electrical (2)
Tech - Engine (8)
Tech - Ignition (5)
Tech - Installation Tips (2)
Tech - Performance Carbs (6)
Tech - Stock Carbs/Fuel System (12)
Tech - Suspension (5)
Tech - Transmission (11)
Trouble Shooting (8)

Forums

http://www.thesamba.com/vw/forum/
http://www.shoptalkforums.com/
http://www.superbeetlesonly.com/forum/index.php?

Collection of VW Technical manuals:

http://www.thesamba.com/vw/archives/manuals/looklistendoitbetter.php
Brakes: http://www.thesamba.com/vw/archives/manuals/dlt_brakes1.php
Ignition timing: http://www.thesamba.com/vw/archives/manuals/dlt_ignitiontiming.php
Timing marks on stock pulley: http://www.thesamba.com/vw/forum/viewtopic.php?t=251672
Ignition system: http://www.thesamba.com/vw/archives/manuals/looklisten_27.php
Carb tuning: http://www.thesamba.com/vw/archives/manuals/carbtuning.php

Vintage VW training videos on Youtube: (timing, Valve adjustment, carb adjustment)

Playlist: http://www.youtube.com/watch?v=BbX-oC1WSbs&list=PL48A3F226C8C787EF
VW How To Videos
  (3)
Stock VW Ignition Timing Vintage Training Videos
 
How to Adjust Stock VW Valves
 
Stock VW Carburetor Adjustment Vintage How To Video
 

Wiring Diagrams online http://www.vintagebus.com/wiring/
Type1 wiring diagrams: http://www.thesamba.com/vw/archives/info/wiringt1.php
Type2 Wiring Diagrams: http://www.thesamba.com/vw/archives/info/wiringt2.php
Type3 Wiring diagrams: http://www.thesamba.com/vw/archives/info/wiringt3.php

Horn Wiring Hell- How to survive it 

Dealer training manuals: http://www.thesamba.com/vw/archives/manuals/practicalwork.php

Collection of VW Trends technical articles from over the years.
http://www.vwtrendsweb.com/techarticles/
34 pict -3 idle problems/troubleshooting 
http://www.thesamba.com/vw/forum/viewtopic.php?t=56411

34 pict -3 idle problems/troubleshooting DVDA flange # carb modification to work with SVDA 
**
http://www.thesamba.com/vw/forum/viewtopic.php?t=365762

Headlight Switch Wiring Diagram
I frequently get inquiries about how a particular model's Headlight Switch is supposed to be wired. This 14 page PDF (Adobe Acrobat Reader required) shows how to properly wire your Headlight Switch for 58-77 Standard Beetles, 71-72 Super Beetles, 3/55-79 Type 2s and 66-73 Type 3s. More models to be added soon, so please check back.

Turn Signal-Hazard Switch Wiring Diagram
Another frequently asked inquiry is about how a Turn Signal Switch is supposed to be wired. This updated PDF (Adobe Acrobat Reader required) shows how to properly wire your Turn Signal and Hazard Switch for Late 68-71 Beetles & Karmann Ghias.

Headlight Dimmer Relay Diagram
The replacement Headlight Relay you buy these days may or may not match what was originally installed in your Volkswagen. Terminal Numbers (or Letters) changed as the design and/or size was upgraded over the years. In addition, some years require an additional wire bridge between two certain terminals for the relay to even work properly. This shows a detailed diagram of which wires go where and why.
This is a PDF File requiring Adobe Acrobat Reader (see previous link description above).

For further details about the Headlight Relay, 
Click Here to see Matt Roberds' excellent article on his website.

Hazard (Emergency) Switch Wiring Diagram
Here's another switch I frequently get inquiries on regarding it's proper wiring. This 9 page PDF (Adobe Acrobat required) shows how the switch is properly wired. Models covered are Late 68-77 Standard Beetles, 71-72 Super Beetles, Late 68-74 Karmann Ghias, Late 68-79 Type 2s, Late 68-73 Type 3s and 71-74 Type 4s. 73-79 Super Beetles & 80-91 Vanagons to be added later on.

Late 68-70 Type 1 Turn Signal Wiring
Probably one of the most requested procedures I get on the phone or email. This PDF shows how the original 4 Terminal Flasher Box is properly connected and how the Turn Signal Switch is wired up on Late 68 thru 1970 Beetles & Karmann Ghias (From Vin 1x8 381 367). Since the 4 Terminal Flasher Box hasn't been available new for almost 2 decades, you can use the 3 Terminal Flasher Box (71-later models, VW Part # 111-953-227A or D [or latest VW Part # 191-953-227]) by following the note in the diagram provided

Ignition Distributor List - By Bosch Number
Sitting there with a distributor you haven't the foggiest what it fits? Check this page out that lists all Beetle, Bus and Vanagon Distributors by the Bosch number stamped on the side of the distributor (Type 3, Type 4 & Eurovan coming soon). Includes cross links to the Ignition Distributor Specifications Page shown below.

The Ignition Distributor Specifications Page
Wanna know what distributor your Beetle, Bus, Vanagon and Type 3 was originally equipped with? This application list has it all, including timing specifications, interchanges and the Bosch Product Numbers for the replacement parts. This page has been heavily updated recently with additional listings showing Washer/Shim Repair Kits, Dust Covers and a host of other internal parts for Distributors not normally found in the current Bosch Product Books or even in VW's ETKA anymore Eurovan to be added soon! Knowledge is POWER!

 Oil Cooler Install Tips and The "Hoover Bit" 
Replace your Oil Cooler, Oil Cooler Stand and Seals with the CORRECT parts and in the CORRECT manner. Wanna know what a "Hoover Bit" is and why it's necessary on "Dog-House" Oil Cooler set-ups? All you need to know is right here.

Without Guesswork 1969

Technical data for workshop use, covers December 1953 through August 1968 (1969 model year), types 1, 2, and 3. Contains measurements, clearances, wear limits, performance data, etc -- lots of details for the detail people! 155 pages.

   Without Guesswork 1972

Technical data for workshop use, covers August 1970 (1971 model year) through October 1972 (1973 model year), types 1, 2, 3, and 4, models imported to USA and Canada. Contains measurements, clearances, wear limits, performance data, etc -- lots of details for the detail people! 157 pages.

  Solex: Selection and Tuning of the Carburetor

This manual from Solex describes how to calculate the correct size of carburetor for an engine (not just VW engines), and how to determine the correct jet sizes and settings. 46 pages.

 Vintage VW Training Film - Valve Adjustments Part 1
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to adjust the valves.

Vintage VW Training Film - Carb Adjustment Part 1
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to adjust the carburetor.

Vintage VW Training Film - Ignition Timing Part 1
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to set the ignition timing.

Vintage VW Training Film - Valve Adjustments Part 2
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to adjust the valves. Part 2

Vintage VW Training Film - Ignition Timing II
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to set the ignition timing.

Vintage VW Training Film - Carb Adjustment Part 2
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to adjust the carburetor.

Vintage VW Training Film - Ignition Timing Part 2
This is a vintage VW training film recorded directly from the original filmstrip and record. It describes how to set the ignition timing.

vw beetle instruction video (1949)

http://www.painteddesigns.nl This vintage vw training and instruction video contains some interesting footage.