Go Back

Start Page

Parts Book
Photos & # 

Page Links

Order With
Credit Card

Timing

Bosch Ing.
Part  numbers

009 Dist. & Switches

Electronic Ing.

Running Hot

Pulley Markings

Q&A
Will not Idle

10/20/02*

Ok then: I just got off the Internet Chat page and the guy said he has a motor just like mine and he sets his timing at 32 degrees and it works great and I should set mine the same as his. Don't do it.

Well then get out the VW Manual and set the timing like the book says.
"Ok this is fine for the stock motor running a stock distributor."
Just make sure you have the correct crank pulley for the distributor your using. *Check  it 

So what makes it so difficult to set the timing on my 1835cc bomb.
I have a Bosh 009 distributor and a degree power pulley, racer John's modified heads and the same cam they used in the latest Magazine article on "Building a 200hp VW"

First off, lets talk about several things that effect the Ignition Timing setting. 
Altitude, Cam Duration, Compression Ratio, Combustion Chamber, intake & exhaust, fuel mixture, Gas Octane rating and much more.

Altitude is no big deal. For every 5000 feet the altitude goes up it's like lowering the compression ratio one point. 

But the Cam makes a huge difference. 
Lets look at a stock cam that has about 215 degrees duration.
Now the intake valve closes 34 degrees after the piston goes by the bottom of the stroke. So it only compresses the intake charge 146 degrees out of a possible 180' . 

Now lets look at a cam with 286 degrees duration.
The Intake valve closes 70 degrees after the piston passes the bottom of the stroke. So this piston is only 110 degrees from the top of the stroke.
So the intake charge is only compressed 110 degrees not 146 degrees as with the stock cam. 

As you can see an engine using a cam with more duration can have a higher compression ratio (actually volume ratio) and still not develop as much cylinder pressure or psi as shown on you compression gage.

So when you figure the compression ratio by calculating the volume of the cylinder and combustion chamber when the piston is at the bottom of the stroke and the volume of just the combustion chamber when it's at the top of the stroke is not telling the full story. 

Lean mixtures produce more heat so pinging accrues sooner,

Dual carbs let you advance the timing slightly, 

A good intake system will pack the combustion chamber more and the best exhaust will empty the exhaust gases better.

A tighter squash area can produce more HP but will require higher octane fuel.

Any oil mixing with the intake charge lowers the octane rating of the fuel. So the oil control ring must be doing it's job or the timing will need retarding.

As you see every thing effects the way you set the timing. Yes even the weather.

One good thing is that the lower the compression is the less effect all the above things will have on timing. ---- Keep the compression low until you know what your doing.---- 

Important:---- The VW Motor WILL NOT TOLERATE DETONATION.
If your engine is pinging when you accelerate then you must either use higher octane fuel or retard the timing.

Normal timing will be between 27' and 31' BTDC when using the 009 distributor.
If you retard the timing below 27' overheating will normally accrue.

---( 27 degrees is about 1 5/8" to the right of the TDC mark and 31 degrees is about 1 7/8" to the right of the TDC mark on the stock 7" dia pulley ) --- But this is not the way to get these figures and all VW pulleys are not the same.

If your motor is set up for high octane fuel and none is available you are going to destroy the motor using regular low octane pump gas.

A good octane booster like 104 can help low octane fuel but it must be available all the time.

We have found that it is better to run lower compression and more timing advance then high compression and retarded timing (keeping within the 27' to 31' BTDC figures)

Raising compression produces horsepower but you better have the fuel to run it and the knowledge to tune the motor or lots of cash for rebuilds.


"Quick my wife is waiting in the Car" --What do I set the timing at.?
Answer.-- Set the timing with a timing light. If your running a 009 distributor you will must always check the timing above 3000 rpm "that's after the distributor advances the timing to it's maximum" you will probably end up between 27' & 31' BTDC.

If you hear any pinging when you accelerate you must retard the timing or get better fuel. 
Never go below 27' and run the timing as far advanced as you can without detonation (pinging)

If it PINGS grab your wallet and start removing money as you are destroying you motor then and there. 

Because it takes a fraction of a second for the spark to ignite the mixture in the cylinder. The spark plug must fire a little before the piston reaches the top of the stroke. If  the timing is slow, the mixture will not be completely ignited before the piston passes the TDC & full power will not be achieved. 
 If the timing is set too far advanced the pressure builds up to soon and tries to force the piston down while it is still moving up. This causes engine Ping.