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Spark Plug Ends

     01/13/03

 Stock VW 1200, 1300, 1500 & 1600cc Air Cooled Motors all use the same Plug "Bosch W8AC"
 Stock heads use the 3/8" reach spark Plugs but most High Performance heads use the 3/4" reach plugs.
 Make absolutely sure you have the correct length (reach) as they can not be interchanged.
 We have never had good luck with the Platinum Plugs in stock motors but worked OK in Race Motors.

Plug Gap is .024" to .028" and should be torqued to 22 to 29 Ft Lbs.  The threads are 14 x 1.25mm
The small threaded terminal should be discarded as they are not used with VW plug wires. Be Sure the engine is cool before replacing spark plugs. It's best to install new washers when replacing used spark plugs. It's not a bad idea to lubricate the threads with antiseize compound. Especially with new heads.

# 1 = Electrodes - Set Gap at .024" / .028"  # 2 = Porcelain insulator  # 3 = Threads 14 x 1.25mm by 3/8" long # 4 = Spark plug information on body of plug           Bosch W8AC for stock VW's # 5 = Small terminal cap not used with VW wires

Depending on style of driving the normal plug gap increases about .001" for every 2500 miles driven.
As the gap increases, the voltage required to fire the plug also increases.
The voltage required to fire the plug at high RPM is about 2 or 3 times as much as required at idle.
The more the fuel/air ratio is off the more voltage is required to fire the plug.
Be sure to remove the Plug Wire by pulling on the boot not the wire, otherwise the connection inside the boot may become separated.
Only remove the spark plugs when engine is cold if at all possible. If you must remove them from a hot motor, be sure to first remove the plugs when cold and then reinstall them with the torque on the light side. 
Normal spark plug torque is about 22 foot lbs.

Use a round-wire type gapping tool on used plugs not the flat feeler gage.

The normal spark plug color is gray or light brown. The problem is some fuels produced today change the plug color slightly. Black & sooty indicates out of tune. Never try to take a plug reading with new spark plugs. It takes about a quarter mile for the plug color to stabilize. You will loose the color just pulling off the road.
Gas additives in modern pump gas can change the plug color, so it's harder to get accurate plug reading then years back.
When taking plug readings run the 1/4 mile at the rpm you wish to check and cut clean. In other words turn off the ignition as you depress the clutch before pulling off the road.
               Plug reading is an art, we will try later to add a section to get you started.

Spark plugs can have a lot wider heat range today then the plugs produced in the 70 & 80's

Never use Helicoil inserts to repair spark plug holes, always use the sleeve type of the correct length. It's best to have the head off so you can make sure every thing is flush in the combustion chamber.