Static timing and dynamic timing

[mamsterla]

I have a 1969 Fiat 124 Spider with a 1438 motor. I have been restoring it. The car does not have a timing cover, so when I replaced the timing belt I reset the timing using a dowel in cylinder 4 to determine TDC - the aux shaft and cams were easy to set. I set the gap on the points to 0.017" using a feeler - the car has an MSD system so the points are only to set dwell.

How can I tell whether I am off by a tooth? I can start the car and it will idle/run. It feels a little low on power, but I have not really adjusted the advance from where it was before. I have what appears to be marks on a separate metal guide, so I will borrow a timing light and check on that.

Picture of what I believe are timing marks:

[Nut124]

How can I tell whether I am off by a tooth?

If you are sure you have the TDC determined correctly with the dowel and the cams are aligned with the marks then the cam timing is correct.

Incorrect ignition timing and/or advance can affect power or even hurt the engine.

Nut124

[RRoller123]

Sometimes the correct alignment, per the various marks, puts 1 of the cams at a halfway belt tooth point, and you have to choose either before or after the exact mark for that cam. Adjustable cam wheels will help that problem.

[baltobernie]

I have what appears to be marks on a separate metal guide, so I will borrow a timing light and check on that.

Your image did not post. Timing marks for this engine are on the timing belt cover. If you have a sawtooth metal strip, that's from a 2-liter motor. It mounts on the passenger side of the block, and the 2L crankshaft pulley has its zero mark several inches from yours.

Ignition timing spec is 10°BTDC at idle. You should see about 30° of total advance at around 3500 RPM. This is the total advance curve for the various Spider ignitions:



Borrow a correct cover, or make your own pointer with the help of a degree wheel.

First thing we check on an unknown motor are the cam wheels. Cars have wheels reversed, or two intake, etc. So confirm you are correct here first.

[mamsterla]

I am certain the cams are good. The only thing I doubt is whether I got the exact tooth on the crank when I changed the timing belt. The belt lines up the cams perfectly with the guides.

I reloaded the image on Imgur here, but it does sound like a 2L timing strip was added to my car way back.

[mamsterla]

I decided to pony up for an Innova 5568 light - I will look at the dwell (I believe the target is 55 degrees), and then see where I am with the current static timing. If the crank was marked for both sides (the 2L on and the original plastic cover), I will see what I can with the light. I did the aux shaft based on pointing it at the tensioner bolt. It run fine, but is low on power. I have no idea how far off the timing might be, so I will try a few things to get it spot on. Basically I may need to borrow a yellow cover to double check the metal strip. I will search for one just for this purpose.

[gchocevar]

Hi,

The picture is very large but it does not look like my 1979. The 1438 marks are on the cover lower driver side, the same side as the distributor on the 1438. Getting a cover would verify your other alignment marks. On both the cover (and the metal alignment mark), the long mark (large pointer) are 0TDC. As you move away from 0TDC the the next mark (pointer) is 5 degrees BTC, then the last mark (pointer is 10 degrees BTC. I can't see a large pointer in your picture.

I once set the idle timing with a light at 0TDC. There is little difference at idle or driving at low speeds. This was with the vacuum advance plugged and just running the mechanical advance. If you shoot for a static timing at 0TDC, the engine should run smooth.

I did work on an Audi 1.8T head and was off one timing mark when I put it together. The experience was like driving on three cylinders. It idled and ran very rough, and not very fast. I hope this helps.

Greg