Timing Enigma - Need Opinions!, Why are my timing numbers so out of whack? Options

[Ansbacher]

Hello all. I have a 74 2.0 dual Dellorto carbureted 914 that is running strong, starts and idles great, and runs at a good temp. Problem is, the car will not run if the prescribed timing values are attempted. Instead, it has to be set at about 25 degrees advance at idle and is probably near 40+ degrees at 3500 RPM. I have triple checked the position of the timing marks on the fan and they are correct for a 2.0 liter engine. The previous owner had rebuilt the engine, could he have installed the fan in the wrong position? Is that possible on these engines.? My vintage Porsche mechanic says to ignore the numbers I am getting, as the car could not possibly run as good as it is if it were truly 25 and 40+ degrees. Can someone tell me what is going on here before I lose what is left of my mind??!!??

[yeahmag]

The only time I've seen numbers like that are when I was building semi-hemi Type I motors. Do you know the compression ratio? What happens when you ignore the idle number and set the max at 32 degrees? What distributor is it?

[Jake Raby]

Find a dyno and optimize it. No matter what the values are, the engine must be happy, and you'll find that with optimization. I once had an engine (10:1) that loved 53 degrees of advance.

Yours sounds like it has a tall deck height or low CR, like yeahmag stated.

[stugray]

Use the TDC timing mark on the flywheel and a variable speed timing light to set the timing. Just pull up on the rear tin (or loosen one side) and push the tabs on the tin back over the engine case. You can see the hole in the trans case from there.
I use a sharpie to hold the gap open so I can see through with the timing light.

I use the static timing method to install the dist. with the engine at #1 TDC
Then you can tweak it by ear at first startup to get it running.
Then I use a variable timing light to set to ~34-36 deg advance at 3500 RPM.
I have a MSD 6AL and a mallory unilite dist.

[Ansbacher]

All great info and advice. Thank you. However, before I investigate further, can someone categorically answer if it's possible for the fan to be installed out of reference (index?). I have seen conflicting information on this and would like to know if it can or can't be.

[Dave_Darling]

If everything is in good shape, it is not possible to install the fan out of position. The fan hub is keyed to the crankshaft with a Woodruff key (a half-moon shaped piece of metal). The fan is keyed to the hub with a single dowel that is offset from the regular three-bolt pattern.

If the dowel is gone, the fan could be 120 degrees off to one side or the other.

If the Woodruff key is gone, the fan could be off by any amount, and would likely change while the engine is running. And come off at some point.

It is, however, possible for the fan casting to be off a little bit. In the Pelican timing article, you can see at least two fans with slightly different castings. I don't think they vary that much, but it may be possible. I know they are not all completely perfectly identical.

--DD

[stugray]

All great info and advice. Thank you. However, before I investigate further, can someone categorically answer if it's possible for the fan to be installed out of reference (index?). I have seen conflicting information on this and would like to know if it can or can't be.

You havent really explained how you are setting the timing.
With the stock fan, there are a few different configurations of marks.
Some will have a 5 deg BTDC & a 27 BTDC mark.

For you to be setting to the numbers you are talking about, you arent using the marks, so you must be using a variable timing light.
Most fans dont even have a 0 degree mark. I put my own on the fan.

[r_towle]

Fan and flywheel cannot be installed out of position.
distributor gear can be installed wrong.

At this point, I would suggest you listen to Jakes advice and get it to a dyno, get it setup properly, then paint new marks on the fan for the future timing needs.

Rich

[SirAndy]

The previous owner had rebuilt the engine

Make sure the PO didn't install the distributor shaft 180 degrees off. The engine will run but the timing will look to be all wrong when it's running OK.

Don't ask me how i know ...
(IMG:style_emoticons/default/dry.gif)

[McMark]

The fan is keyed to the hub with a single dowel that is offset from the regular three-bolt pattern.

If the dowel is gone, the fan could be 120 degrees off to one side or the other.

If the Woodruff key is gone, the fan could be off by any amount, and would likely change while the engine is running. And come off at some point.

Dave, the three holes are not perfectly symmetrical. So even without the pin it won't really go on any other way.

Good point about the sheared key. (IMG:style_emoticons/default/agree.gif)

[Dave_Darling]

I didn't realize that, McMark, thanks! Ya learn something new about these cars every day...

--DD

[stugray]

At this point, I would suggest you listen to Jakes advice and get it to a dyno, get it setup properly, then paint new marks on the fan for the future timing needs.

Rich

That is a new one on me.
To set the initial timing (or to get the timing marks right), you need a dyno.

Who knew? (IMG:style_emoticons/default/confused24.gif)

[Ansbacher]

If the distributor gear was in 180 degrees backwards, wouldn't my good running timing points be nowhere near the actual timing marks, as it would end up on the opposite side of the fan circumference? My good idle right now is very near the existing 3500 RPM 27 degree red mark. Baffling...

Ansbacher

[stugray]

Could you explain your process for setting the timing? What timing light?

Have you looked for the TDC mark on the flywheel & compared it to the ones on the fan?

Do you have a MSD ignition?

[ChrisFoley]

If the distributor gear was in 180 degrees backwards, wouldn't my good running timing points be nowhere near the actual timing marks, as it would end up on the opposite side of the fan circumference? My good idle right now is very near the existing 3500 RPM 27 degree red mark. Baffling...

Ansbacher

The only way you would get incorrect timing readings if the distributor is installed in a different orientation is if you put the induction clamp on the wrong spark plug wire.

[Ansbacher]

Pardon the ignorance of a Newbie, but where is the tin that I remove to see the flywheel- up top or from down below?

Answer to how I check timing - Conventional timing light, clipped to #1 wire, shoot down fan access hole. I see the red 3500 mark at my 900 idle, instead of being near the white mark where it should be. Not sure what else you want me to say...??..

Really appreciate the help on this, guys.

Ansbacher

[r_towle]

OK,

To keep you from getting to confused, try this.

Looking at the top of the transmission there is a small hole, there is also one at the bottom...
Some, if not all, flywheels have a notch in them that will be up top when you are are number one TDC.

If you remove the rear tin, the part that goes side to side, you can find the hole.
That will give you the location of TDC for number one cylinder.

At that point, do not over think this.
Take a picture of your distributor with the cap removed and the rotor in place.
Post that picture here.

For Stu and his always helpful remarks...
A custom motor is best tuned in action if you want everything you can get from a motor. Its not helping this guy to argue what you believe versus anyone else.
Its just how it works best is at a dyno with a professional who knows how to tune a car....

For the OP, lets talk facts.
There is a special tooth at the bottom of the distributor with one side larger than the other. This makes it impossible to install your distributor 180 out. Its just not possible without breaking it first.

It is possible to do two things that may have happened.
One, the tooth on the bottom of the distributor could have been flipped around if someone rebuilt the distributor, took it all apart and installed that piece wrong.

Two, the distributor is driven by a gear which runs off the cam gear.
That distributor drive gear can be pulled out once you remove the distributor and turned to many different (and wrong) positions, then reinstalled.

So, find TDC for number one.
Verify by checking your valves
Verify by inserting something through the spark plug hole to top of piston.
Verify by notch in front fan housing lining up with notch.

Then you have TDC
YOu can then remove the drive gear and install it correctly.

That may not be your problem, but it sure sounds like it.

rich

[stugray]

Here, it is even at TDC. Took me ~1 minute to get it to TDC, another 30 sec to take the video.

http://youtu.be/QtPd5qzyTk8

[yeahmag]

Damn near impossible to do that if he's got the stock FI in place... And if you're flywheel has been lightened that mark is long gone!

Just making sure I make this process more difficult ;-)

[Jake Raby]

I'd definitely make sure that your timing marks are correct in relationship to TDC. Some fans have a )* and a 28* mark, and I have seen a few with a 17.5* mark that came from Euro 914s that were carbureted.