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914 Timing and Dwell, Adjustment
 
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Pelican Technical Article:

914 Timing and Dwell, Adjustment

Pete Dubler

Time:

1 hour1 hr

Tab:

$0

Talent:

**

Tools:

Metric wrench set and metric socket set, flathead screwdriver and Phillips screwdriver, timing light, Sunpro CP7676 dwell/tachometer, Adobe Acrobat for reading and printing Pelican Timing Mark Template, computer, 10mm wrench

Applicable Models:

Porsche 914 (1970-76)

Parts Required:

If you don't having the timing light and the Sunpro CP7676 dwell/tachometer, purchase or borrow from an auto parts store

Performance Gain:

A properly timed 914 mill

Complementary Modification:

Replace the distributor

There doesn't seem to be too much technical information available in books on how to set the dwell, timing and idle on the 914.  With this in mind, this technical article aims to ease the process by detailing the steps for the total beginner.  You will need some basic tools for this, plus a good timing light, a dwell meter, and a tachometer.  Some timing lights are adjustable, so all you need is the mark for Top Dead Center of cylinder #1.  This article will show you how to time your car without one of these special timing lights, even if your timing marks are missing. Also used in this article was a  electronic Sunpro CP7676 dwell/tachometer that is generally pretty useful.

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:

Distributor
Type
Centrifugal Change Vacuum Change Dir of
Change
Beginning RPM RPM
Degrees
RPM
Degrees
Ending
RPM
Degrees
Begin
mm Hg
Ending
mm Hg
Degrees
022-905-205D 1050-1200 1500
14°-17°
2000
17°-20°
2900
22°-27°
100-130 200
11°-14°
Adv
60-100 150
8°-12°
Ret
022-905-205E+F 700-1050 1500
10°-15°
2000
14°-19°
3000
22°-27°
100-130 200
11°-14°
Adv
60-100 150
8°-12°
Ret
022-905-205J 700-1100 1500
10°-15°
  3000
22°-27°
100-130 180-200
11°-13°
Adv
022-905-205AA 980-1180 1500
14.5°-19°
2500
23.5°-26.5°
3400
29°-32°
120-160
(90-120)
240-267
(180-200)
9°-12°
Adv
73-160
(55-120)
193-254
(145-190)
Ret

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:

The Cam angle, or dwell angle is the number of degrees through which the distributor cam rotates while the breaker points are closed.  It is directly related to the breaker point gap.  Decreasing the breaker point gap will increase the cam angle.  If the cam angle is too small, the current will have insufficient time to pass though the primary winding of the ignition coil, and a weaker spark will result.  If the cam angle is too great, the breaker points will not open far enough, they will tend to stick together, and misfiring will result.  The best method of adjusting breaker points is by means of a dwell meter."

You usually hook up the dwell meter by attaching one lead to ground and the other to the negative terminal of the coil.   Start the car and measure the initial dwell angle.  All 914s should be set to 44°-50° for all RPMs.  If your angle is not in this range, remove the distributor cap and loosen the screw shown in Figure 1.   Move the small set of points outwards to decrease the angle, or inwards to increase the angle.  Replace the distributor cap and start the engine.  Check the angle again and repeat the adjustment until it is within the proper range.  The dwell meter shown in Figure 2 shows the dwell angle set at 45°.

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.

Once you have located TDC, check to see if any timing marks exist on the impeller inside the fan housing.  To do this, set the engine at TDC for cylinder #1, and then rotate it clockwise (from the perspective as if you were standing behind the car looking at the '914' emblem.  The timing marks should appear at about 1/2" to the left of  the TDC mark for 1.8L engines, or about 2" to the left of the TDC mark for the 1.7L and 2.0L engines.  If they exist, then great, you probably don't have to remark them.  If they are missing, you can remark them using our handy template.  It was designed to be placed on top of the impeller to help you create the timing marks for all 914 engines.  To view and print this template, you need the Adobe Acrobat reader, available free from www.adobe.com.   Click here to view and print our Pelican Timing Mark Template.  Take the template and line up the arrow that points to TDC with the paint mark that indicates TDC.  This is shown in Figure 3.  Or line it up with the notch in the impeller housing shown in Figure 4.  I recommend using some double-sided tape to attach the template to the impeller while you are making the marks.  Becareful not to let it slip down into the impeller housing.  Once you have it properly lined up, mark the impeller with some paint or some white-out.  This is the mark that you will be setting the timing to.

In order to set and adjust the proper timing, you need to rotate the distributor.  Take the cap off of the distributor (to gain some working room) and loosen the clamp that holds the distributor in place.  This clamp is shown in Figure 5.  You may need to remove a connector or two from the fuel injection to reach the clamp and have enough room to get a 10mm wrench on it.  Loosen the clamp, but be careful not to rotate the distributor.  Now, replace the cap, and start the car.   The car should be warmed up to normal operating temperature before you adjust the timing.

Now hook up your timing light.  Figure 6 shows a pretty generic timing light that works inductively.  A small clamp goes around the ignition wire for cylinder #1, and detects when the cylinder is firing.  The ignition wire for cylinder #1 is near the TDC notch on the distributor housing, and is shown in Figure 7.  Now aim the strobe light at the hole in the impeller housing.  The fan blades should look like they are standing still, even though the engine is turning at about 900 RPM.

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 5th 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.

20impeller_small.JPG (2670 bytes)


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

Figure 1

914 Points

Figure 2

Dwell Angle Reading

Figure 3

Template for Timing Mark

Figure 4

Template Lined up with TDC

Figure 5

Distributor Adjustment Clamp

Figure 6

Ignition Wire for Cylinder #1

Figure 7

Ignition Wire for Cylinder #1

Figure 8

1.8L Idle Adjustment

Figure 9

Tachometer Reading

Figure 10

1.8L Idle Adjustment

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Comments and Suggestions:
GlennM Comments: Does the 1975 Porsche 914 1.8L EC Series engine require a Timing Chain or Belt? I cannot find any information on this
August 5, 2016
  Followup from the Pelican Staff: I thought they are a chain, but my info doesn't go back far enough to confirm. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
BW Comments: As for the static timing, is it easier to start the motor using the timing markred than using the TDCzero mark? Which is better?
May 21, 2016
  Followup from the Pelican Staff: What vehicle are you working on? - Nick at Pelican Parts  
buddy Comments: Quite helpful for a novice, more info than I received from the manual.
October 25, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
mmmmgood79 Comments:
May 22, 2013
hannuzke Comments: Great artcile, thx! My I suggest enrichment by mentioning the combination of engine and distributor type in the table.
August 10, 2012
  Followup from the Pelican Staff: Thanks for the feedback. We appreciate it.
- Nick at Pelican Parts
 

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Page last updated: Fri 12/9/2016 02:16:36 AM