How to use a timing light on the 1438

[70spider]

Hello, I have a bit of a problem. I have never used a timing light before. I watch videos and it seems simple enough however there is one issue, the 1438 does not have a harmonic balancer with timing marks on it. It has a pulley which is fed oil internally to dampen the vibrations. I do have a notch in the pulley which indicates TDC when the timing belt cover is on. I thought about getting some timing tape but there is not enough surface area for it to attach the tape without it being ripped off by the water pump/alternator belt. So if I don't have degree marks to see when the strobe hits them how to tell what degree I am at? Are there a specific type of timing light that will tell me what the timing is without the degree marks?

[Nut124]

You will need to have a reliable TDC mark on the pulley and a pointer. It would be a good idea to try to check, verify these marks line up at TDC.

As to the degree marks, you can do the math, based on the diameter of the pulley, and mark on the pulley 10BTDC, 20BTDC and 40BTDC or so. Just make sure to know which is the zero (TDC) mark.

Alternatively, you could get a timing light with an adjustable advance. These are handy. Then, you only need to look at the TDC marks. Vary the light advance setting until the TDC marks line up. The light will show what the advance is.

[70spider]

According to the compu-tronix unit I can't use a dial back light. So, I thought about making the marks in different color paint to keep things clear.
The unit says to set @ 6 degrees initial and 35 degrees @ 3200 rpms. I'll make marks at 10, 30, 35 and 40.
Thanks again Nut124

[Nut124]

Can you explain why you could not use a timing light w adjustable advance? I cannot think of a reason.

Is the CompuTronix an ignition system? Does it use vac advance?

[70spider]

The Compu-tronix is an electronic system, no vac advance. I got from Allison's automotive awhile back. The instruction book says not to use a dial-back light unless the delay is set to Zero I don't think they, compu-tronix, are in business anymore.

[Nut124]

Interesting. Maybe the Computronix is a multispark system that confuses the dial-back delay calculation.

[18Fiatsandcounting]

I'm not very familiar with electronic ignitions, but I have heard that there are occasional problems with dial back timing lights and ignition systems like Computronix, MSD, Pertronix, etc. I'm not sure what the underlying issue is.

A couple thoughts:

1. You can get an "OK" ignition timing by using the cam timing marks. These would be the holes in the backs of the cam pulleys referenced against the nibs in the front of the camshaft housings. With a standard timing light (not dial back), you can adjust the timing so the holes are lined up with the nibs, advance it just a bit, and this will likely get your timing close enough to start with. You can also verify that the pulley holes move as you rev the engine, which means your advance is working. Also, in a darkened garage with a bright timing light, you can see whether your timing is even in the ballpark, even with the engine just cranking and not starting.

2. Do you still have your original distributor? The old points and condenser distributors are just fine for the older 1438 engines, and the only real problem is that points are a bit of a pain to adjust and excessively worn distributors can result in timing that is a bit "jumpy". So, if you have your original distributor, you could try that again.

-Bryan

[70spider]

Do you still have your original distributor? The old points and condenser distributors are just fine for the older 1438 engines, and the only real problem is that points are a bit of a pain to adjust and excessively worn distributors can result in timing that is a bit "jumpy". So, if you have your original distributor, you could try that again.

Yes I have the old distributor. I thought about points, they work great in the old Ford, but the P.O. took out the stock system and in the process hacked up a bunch of wiring for a weird electronic ignition box, which ended up melting. So I put a petronix kit in the distributor and it just failed after 5 years. I have no clue on how to go back to points, but probably should research on how. The Compu-tronix was just hanging around so I put it in to get the car running again.

[70spider]

I went rummaging around my parts boxes and found a brand new distributor I bought years ago, I thought I had sold it hmm. Any rate, it has the points and condenser, I set the gap @0.45mm, but it needs the rotor.

So as it stands right now I have a 12v and a ground wire going to the coil pack on the compu-tronix. These I know would go to the coil. The distributor has one black wire feeding it, this I assume is 12v. I also assume the distributor is grounded through the block? Also, I have the old coil, ballast resistor, and bracket.
Could someone draw a rudimentary drawing of the set up so I can see where it all goes. Many thanks.

[18Fiatsandcounting]

I also assume the distributor is grounded through the block? Also, I have the old coil, ballast resistor, and bracket.
Could someone draw a rudimentary drawing of the set up so I can see where it all goes.

Yes, the distributor is grounded through the block. You do have the block mounted distributor, yes, not the one on the rear of the exhaust cam housing?

I can't draw a picture very well, but here's how it's wired in general. You should have a light blue/black wire near where the coil is mounted that has +12V on it whenever the key is in the run or start positions. That powers the coil, and it's connected to the B+ terminal on the coil. The other terminal of the coil goes to the one connection on the ballast resistor (usually a red block about 2" square) and the other side goes to the distributor connection. Inside the distributor, you have the points with the condenser (capacitor) across them.

In a nutshell, what happens is that when the points are closed and the ignition switch is in run or start, the coil is energized and builds up a magnetic field inside it. When the points inside the distributor open up, that collapses the magnetic field and that energy has to go somewhere, and so it goes to the spark plugs to create the spark.

The condenser (capacitor) is there to minimize arcing across the points, which lengthens the lifetime of the points and reduces AM radio interference. Not that anyone listens to AM anymore, but back in 1970, they did.

-Bryan

[70spider]

Update: The "new" distributor didn't work out. I was getting 12v to the points but no spark, it turns out the points on the "new' distributor had a thick layer of carbon on them, or something black.
Meanwhile perplexed I looked over the old distributor and realized the two dizzys are different. The old one is a S124C and the new a S147. The significance of this is a while back I ordered a new cap and rotor for my 1970 spider and received what I believed to be the correct parts, unbeknownst to me their are multiple distributors that fit the car. So when I put the new parts on the old distributor I thought I was good to go, nope. Again 12v in no spark. So I concluded my Petronix unit gave up the ghost. So I put the stupid computronix unit in the car, I have read bad things about this unit so it was only temporary until I could get a dstributor to put in. It turns out the new cap (S147) has a notch to indicate which way it is suppose to be put on and the S124C dizzy does not have a relief for the tab so my cap was catawampus, thus no spark. I put the old dizzy back together with my old parts and will give it a shot tomorrow.
I want to give a shout out to Midwest-Bayless for listing their ignition parts by which distributor they are for, this has helped me a lot. It turns out the cap, rotor, points and condenser for the S147 are not interchangeable with the S124C.

[18Fiatsandcounting]

I want to give a shout out to Midwest-Bayless for listing their ignition parts by which distributor they are for, this has helped me a lot. It turns out the cap, rotor, points and condenser for the S147 are not interchangeable with the S124C.

Thanks for that. One thought: I thought the distributor for the 1438 spider engines was an S124B, and the S124C was for the 124 sedan and wagon? Maybe similar enough to work OK, but something to keep in mind.

Yes, it can be very frustrating with Fiat distributors, where the model number seemed to change every year. Some have interchangeable parts, but many don't. I have a '71 spider with a distributor from a later model year, and while it works just fine, I have to be careful when it comes to buying points, rotors, caps, etc.

-Bryan

[70spider]

Update: It took a minute but I got him running.