Getting a minor misfire at idle (not consistent) then much bigger misfires under load. Changed the TFI module (it has some corrosion on the back side) thought it was the problem after seeing that. It ran possibly worse after that part was changed. Next step is changing the spark plugs and wires but it appears the previous owner recently changed those so my gut is telling me that’s not the issue either. Distributor cap and rotor is next there’s a little wear on the terminals (white powdery deposit) but under the rotor I find heavy rust.

What do you all think I should do? New distributor?

 

Where do you live, do you have smog inspections? And what are your plans for this engine? If it were mine, I would put in a new distributor, but get a HEI unit and get rid of the EECIV. Then later on get a regular 2bbl carb and get rid of all those sensors and wires.

 

I do live in an inspection area but I’ve registered the truck as historic in order to be exempt from this requirement. I’m going to have to educate myself on the HEI ignition. I was thinking of buying a top end kit from summit and changing things around but just wanted this old turd to run to the lumber yard without dying in the meantime.

 

If you are planning on modifications later on, you definitely want to get rid of this computer system that is on the engine. You will not believe the amount of wiring and sensors that leave when you do that.

The HEI is a aftermarket hybrid distributor. It has the module and the coil all built into it , so it's just hook up one ignition hot wire from your old ignition coil and you are running. The only drawback to this is it makes the unit large in diameter, so on a Ford sometimes the clearances to various pieces on the engine are close.

You could also get a Ford duraspark II system. It is what Ford used on your same engine when it was the 351w HO. You will need a distributor, the ignition module, and the wiring harness between the distributor and the module. It has more wires and takes a little more effort to install, but it is all Ford if you want to go that route.

With either of these other distributors, you will be ready for any modifications later.

 

Two thoughts immediately came to mind:

Seems to run worse with a new TFI module? Definitely revisit that. Make sure there wasn't a problem with the installation, such as a connection not seated properly. If good, your new module is probably bad. If to be replaced, make sure to get a different brand from another source. Don't go back to the same store and get another potentially faulty part from the same bad batch.

What's with all that rust under the rotor? Are those two metal parts supposed to move relative to each other? I'm not familiar with that model distributor, but is that part of the centrifugal advance mechanism? Are there any electrical connections inside the distributor that could have been degraded due to all that moisture?

 

I did not think any system using TFI / computer had centrifugal advance?
So I dont think there is any centrifugal advance movement that the rust would cause any issues in my book.

Now rust on the "star" or coil pickup down deeper might cause issues?
Dose the TFI unit take the place of the pickup coil in this dist.?
I know they changed where it is mounted on later years and why I asked?

I think I would take look as the star and the coil or the end of the TFI unit if it is used as the coil.
Dave ----

 

TFI system never had any advance mechanism. It was always used with computer control, the distributor was always locked mechanically.

 

This is the new ignition module it broke when I removed it to replace the distributor.

Broken tfi module

Old distributor with Ford part number

Data tag on old distributor

Connection for ignition module on old distributor.

i wanted to follow up for everyone’s reference. I ordered a remanufactured distributor and installed it today. It fixed the problem. I made a comment about how the truck ran worse after installing the new ignition module on the distributor. It ran worse either because the connection on the distributor got pulled and torn even worse or because the new module was junk from the parts store. Pictures of the culprit.

 

First thank you for the follow up.
You dont know how many come for help and we never know if it got fixed or they put gas and a match to it LOL

I would say that connection in the dist. was a BIG cause for the trouble you were having.
I wonder how many look like that but because of where it is and hard to see is not checked?
That is one for the books as they say.

BTW when you install TFI units there should be thermal paste between the TFI and dist. to help heat transfer from the TFI to the dist.
With out it the TFI could burn up. Wonder if the heat was going to the plug and not the body of the dist.?
Unless you wiped it off the replacement TFI did not look like it had any paste on it and that could be why it broke?
If it had paste then it was a bad new part like that never happens
Dave ----