914 Timing and Dwell,
Adjustment

Difficulty Level 2

Difficulty scale:
Adding air to your tires is level one
Rebuilding a 911 Motor is level ten

     The 914 is timed with it's spark fired at a point before each piston reaches Top Dead Center or TDC.   The fuel in the combustion chamber takes a certain amount of time to explode after it is lit.  Higher octane fuels burn more slowly due to the higher level of oxygenated fuel.  Slower burning fuel means lower temperatures for the combustion chamber.  Proper timing of the engine is necessary for the explosive force from combustion to push on the downstroke of the piston.  We won't jump into the thermal and chemical processes here, but the overall concept is that proper timing results in peak power output.

     The 914 distributor has a centrifugal advance built into it.  This mechanism causes the distributor timing to change as the engine's RPM increases.  The advancement of the timing is necessary because at higher RPMs, the engine needs to ignite the fuel earlier than at idle.  In other words, if there were no centrifugal advance, then at higher RPMs, the full force from the combustion would impact the cylinder when it was already through the major part of it's stroke.  This would result in lost power output.  The centrifugal advance changes the timing so that ignition occurs earlier.  Additionally, the fuel injection may advance or retard the timing based upon the vacuum pressure from the engine.  The different distributors used with the 914 have the following advance/retard characteristics:

     The first step in tuning your car is to adjust the dwell angle (sometimes referred to as cam angle). Changing the dwell angle will change the timing, but changing the timing will not affect the dwell angle.  The automotive encyclopedia explains the definition of dwell/cam angle:

Figure 2:
Dwell Angle Reading

     The first step in setting the timing of your car is to find Top Dead Center (TDC) for cylinder #1.  There are a few ways to determine the exact location of TDC, and these are documented in our Pelican technical article, "914 Valve Adjustment Made Easy."  This article details the process of finding TDC as well as the locations of the timing marks on the impeller.  To rotate the engine to find TDC, reach down to the front of the impeller and pull up on the right side of the impeller.  Do not use a screwdriver on the fan blades, as this will break them off.  If you are having trouble turning the engine, remove the spark plugs, and/or push the car in gear to get to the right point.

Figure 4:
Template Lined up with TDC

Figure 7:
Ignition Wire for Cylinder #1

Figure 8:
1.8L Idle Adjustment

Figure 9:
Tachometer Reading

Figure 10:
1.8L Idle Adjustment

     At this point, you need to hook up your tachometer.  One wire usually goes to the negative terminal of the coil, and the other usually goes to ground.  For 1.8L engines, the timing is set between 800-900 RPM.  To adjust the idle on the 1.8L engines, turn the air intake screw shown in Figure 8.   Adjust the idle until the engine is running with the 800-900 RPM range.  The tachometer with the reading of 820 RPM is shown in Figure 9.  Now, while pointing the strobe timing light at the hole in the fan housing, rotate the distributor.  If you rotate it back and forth, you should be able to see the little white mark that you made appear in the upper notch of the fan housing.   This white mark is shown under the timing light in Figure 10.  Note that the engine will rev up or slow down depending upon where you set the timing.  Note that for 1.8L engines, the timing is 7.5° BTDC (Before Top Dead Center) at 800-900 RPM.  Also make sure that you have the vacuum hoses to the distributor disconnected and plugged, as the vacuum advance/retard will adversely affect your timing readings.

     For the 1.7L and 2.0L engines, the process is a little trickier.  You need to pull on the accelerator cable or throttle body until you get the engine revving near 3500 RPM.  While holding the car at 3500 RPM, and pointing the timing light at the impeller, rotate the distributor until the timing mark appears.   It helps to have an assistant for this task.  Note that for 1.7L and 2.0L engines, the timing is 27° BTDC at 3500 RPM.

    Well, that’s about it. Your car should be well-timed when you finish this procedure, and hopefully running well.  You should replace your cap, rotor, condenser, and points often if you want your car to remain in tip-top shape.

     If you enjoyed this article, and would like to make sure that this site stays up, and articles like this one continue to be written, then please make the effort to support Pelican Parts by ordering all your parts through us.  You will find that our prices are very reasonable, and our customer service strives to be the best.  If you have any questions or comments about this helpful article, please drop us a line.

Pete Dubler has also written an article on timing your 914 with carbs.

James K. Thorusen adds his own spin to the timing problem:

I had a tussle with my 914 when I first got it, owing to the fact that the plug wires were mixed up. The thing refused to run, although once in a while, I got a tremendous backfire.

Here’s what you need to check to make sure that the ignition is close enough to correct to enable the car to start and run:

These instructions are given for the 1.7 litre engine, because it has all three timing marks on the fan. Later engines have fewer timing marks; the ‘73 - ‘74 2.0 litre engines do not have the 5 degree mark, and the ‘75 - ‘76 engines do not have a TDC mark, although they do have a scribe line on the flywheel. I have found it good practice to add the 5 degree and TDC marks if not present; there is a technical article and template here on the Pelican Parts web page that will describe how to do this.

O.K., then we proceed as though we have a 1.7 litre engine, with all three timing marks. The type IV engine’s timing marks are on the BASE OF THE FAN. They are TDC, 5 degrees before TDC (static timing mark) and 27 degrees before TDC (dynamic timing mark). Now, the trick is, these timing marks are placed where they would be useful for a type IV Volkswagen, from which the engine is derived. But in a VW, the engine is in the rear of the car, behind the rear wheels. So, the timing marks can be easily seen in a VW. In a 914, they are all but invisible; you will need a small mirror to see them, or else you will have to crawl into the engine compartment , butt your head up against the sound deadener pad, and look through the hole in the fan shroud backwards in the general direction of your navel to see them. They are on the end of the fan closest to the engine proper, the "base" of the fan. I presume you have a Haynes book; if not, go buy one; they are not perfect, but they form an excellent starting reference. In the Haynes book, page 65, fig. 3.6, you will see an angle for the slot in the distributor drive shaft described. This angle is also pretty much the same for the tip of the rotor when the distributor is installed.

Bring your engine to TDC on the compression stroke on #1 cylinder. This can be done by rotating the engine until the TDC timing mark lines up with the notch in the fan housing, and, with the left side valve cover off, check to see that both valves on cylinder #1 (REAR cylinder on LEFT side of car) are closed (a little bit of free play in the rocker arms). If you are on the TDC mark with either valve open, you need to rotate the engine one complete revolution to the next TDC and at this point, both valves should be closed. I know this is a hassle, but until you do it, you will not know where you are. Once you are lined up at TDC on the compression stroke on #1, check to see if the rotor is pointing toward the fan shroud at about the 12 degree angle depicted in the Haynes book. If not, you will have to pull the distributor and rotate the distributor drive shaft to the correct alignment per paragraph 6 on pg 64 of the Haynes book.

Once you have the distributor drive shaft orientation correct, then check for corect distributor body orientation. There should be a tower (wire socket) in the cap directly above the tip of the rotor when the cap is properly installed. This is the socket for the #1 plug wire. If no tower is close to the position directly above the rotor tip, loosen the distributor clamp bolt and turn the distributor slightly until there is a tower directly above the rotor tip. If you can read the numbers on the cap, this should be #1 tower. If no numbers are visible, rotate the distributor so that the closest tower comes to the point directly above the rotor tip. The vacuum advance unit should be sticking out to the left front of the distributor when it is correctly oriented. It is doubtful that you will be able to turn the distributor far enough to get 90 degrees off because of all the junk hanging off of it, and the close quarters around it, so just turn it to the point of least resistance, and then line up the closest tower. This should be #1.

Now, we need to check the wire orientation in the cap. Remember that the flat 4 engine has an unusual firing order: 1,4,3,2. The wire connector in the cap directly above the #1 cylinder TDC position of the rotor is the #1 plug wire; it should go to the REAR cylinder on the LEFT side of the car.

The next plug wire CLOCKWISE around the distributor (as viewed from the top) is the #4 plug wire; it should go to the FRONT cylinder on the RIGHT side of the car. The next plug wire CLOCKWISE around the distributor is #3; it should go to the REAR cylinder on the RIGHT side of the car.

The last remaining plug wire (just before you get back to #1 in a clockwise direction) is #2; it goes to the FRONT cylinder on the LEFT side of the car.

Once you have this orientation correct, finish up by doing a static timing of the ignition system. Rotate the engine just slightly in the backwards direction (can be done by nudging the car backwards just a bit in 5^th gear) until the 5 degree static timing mark is in the notch. Remember, this is literally only 5 degrees of rotation of the engine, so make any movement VERY slight, or you will go right past it.

Once you have the timing marks lined up, connect your voltmeter (or 12 volt test lamp) to the coil ( - ) terminal and ground. Turn the ignition on, loosen the distributor clamp bolt (if you haven’t already), and rotate the distributor clockwise as viewed from the top. The voltmeter should go to zero (lamp out) when the points close. Now, rotate the distributor COUNTER-clockwise until the voltmeter just jumps up to 12 volts (lamp lights). Rotate no farther than the point where the voltage just appears (lamp lights), indicating that the points have just opened. You may have to go back and forth on the rotation until you find just the right spot, but always approach it from the COUNTER-clockwise direction, and stop immediately when the voltage appears (lamp lights). Tighten the clamp bolt to lock the distributor in this position.

Hop in the car, and crank it up. If everything else is OK, the engine should now run. It is best to perform a dynamic timing adjustment with a timing light as per paragraph 4 on page 64 of the Haynes book, but the above should get your car running.

Note: The timing and dwell angle interact. The above assumes that the dwell angle (point gap) is somewhere close to correct. There are instructions on page 63 (Paragraph 3) of the Haynes book for setting dwell angle. Use the feeler gauge method before you perform the static timing setup above if you are not sure, then check the dwell angle with a dwell meter after the engine is running per paragraph 3 page 63 in the Haynes book. Adjust as necessary, and then perform dynamic timing as described in paragraph 4 (page 64) of the Haynes book.

Good Luck,

Jim T.
entropy@hughes.net

Copyright Date of Origination by James K. Thorusen This material may be reproduced by anyone without charge or notification.

Dave Darling (dave@pelicanparts.com) adds:

This is a stock 914 impeller (fan). It came out of my 74 2.0 liter. This photo is taken as if the front of the engine were toward the top of the photo. The blades are what you usually see through the hole in the fan shroud. The D-jet timing mark, 27 deg BTDC, is visible just to the left of center. The TDC mark is visible about four fan blades to the right of the timing mark. Note that the paint marks were added by me, because I was tired of trying to see the actual marks through that hole in the shroud. The actual marks inscribed by the factory are on the rear part of the fan only, and are rather tough to see. Hopefully this will show in more detail just where the timing marks are located on the fan.

John Larson adds:

It has been brought to the 914 list's attention that the need for disconnecting (and plugging) the vacuum hoses while setting the timing on the d-jet cars has been omitted from the tech article. In fact, I just looked and that most important step is also missing in the procedure for the l-jet engines as well. I hope you'll correct these flaws in your otherwise valuable resource. John