Unknown Part for '78 Lincoln

[jakescervino]

In addition there are 5 other ignition timing vacuum switches for other applications in 1978 & 1979 with different part numbers.

What do you mean by "different applications"? Do you mean that the exact same part is also used in different makes of vehicles? Will a part similar to this one work in my Lincoln even if it wasn't specifically made for a Lincoln car? Also, since this part has something to do with ignition timing, am I hurting the car by driving it without it connected?

[jakescervino]

If you don't need the part to be functional, just clean up the old one, repaint it, and hang it like it's supposed to be working.

I won't tell.

Yeah, I don't even think it was functioning when I bought the car. It was plugged in and mounted onto the ICM, but there was no vacuum hose on it. However, I am new to old cars and I'm not sure if my Lincoln needs the part to be functional or not. If it has something to do with ignition timing, it must be important, no? Also, I could just put the broken one back in and keep the secret between us, but it would still bother me....

[action]

Applications to vehicles -

A part (in this case a ignition timing vacuum switch) for your specific application (1978 Lincoln with 400 engine) has a specific part number

Other ignition timing vacuum switches for different applications or different models years engine sizes have different part numbers.

So an application is specific to some set of data. Other applications would be different. Just like an air filter of a certain part number has a certain application. Even though it is an air filter the application of that air filter is not for every engine combination made.

The part number I listed below for your vehicle has only the applications I posted in my post of 04 Nov 2020 08:35. That exact part will not fit or apply to any other vehicles outside of the applications in my post dated 04 Nov 2020 08:35.

Will other ignition timing vacuum switches work for your vehicle? Not according to Ford at the time they published the master parts catalog.
Since the part will be difficult to find swiftly you have some choices to make -
1) Do nothing
2) Keep searching for the correct part for your application. When available buy it and install.
3) Install a different ignition timing vacuum switch for a different application and hope it works
4) Repair/modify your existing part

My limited understanding of what this part may do is it sends a signal to the ignition module based on elevation of the vehicle. The module will retard the base ignition timing (likely to eliminate spark knock) once the vehicle is driven to a certain altitude and beyond. That altitude set point can be different and the amount of ignition timing that is retarded can be different for each applications. However this is a guess as to function on my part. It is 40+ year old technology on a very limited vehicle application. Because most other FLM vehicle and engine combinations have a different type of module without that switch.

Are you hurting it? (Meaning the engine) Have no clue. My guess is no, unless you experience engine pinging or spark knock. And at this time of year that situation occurs less because the ambient temps are so low as compared to the summer. But all of this is a guess on my part. The name of the part is an engine timing vacuum switch. Based on the name of the part, this switch has an influence on engine timing.

The shop manual may have more data. I would encourage you to look that up in the Ignition Section of the shop manual. Other sources may be TSBs or 1978 new model intro booklet for FLM service technicians. However that may be be hunting for a needle in the haystack to find those publications.

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[jakescervino]

Okay, I understand. I am not sure if I already said this, but I have a Haynes manual for my Lincoln and it had no information pertaining to this part (but I will look again just in case). I guess I will fix up my old part the best I can for now and if a miracle happens and I end up finding another one, I will replace it. At least I have a lot more information now in regards to the name of the part and its function. If I come across any new info, I will post it here to let you know. Thanks again for helping me.

[action]

Non-FLM shop manuals (in my opinion) are worthless. (Motors, Haynes, Chilton)

They might give you some basic data for maintenance. However they are so generic for repairs because they cover multiple years and models so the detail is really lacking.

They served a purpose for vehicles from the 1960s and earlier. And as vehicles got more complex these sources really missed the mark with detail.

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[jakescervino]

I didn't know that. It does seem to be lacking a lot of detail even though it claims to cover '78 Lincolns. I'll be sure to look for an FLM shop manual next time.

[action]

You can get a pdf shop manual from this site for a $20 donation - may be
https://www.thelincolnforum.net/phpbb3/ ... =7&t=28049

This is what hard copy looks like.
https://www.ebay.com/itm/FACTORY-1978-F ... Sw6XZflHFp

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[jakescervino]

I would definitely spend the $20 for one as that would be super helpful, but it looks like the 1978 one isn’t offered. Would the 1977 or 1979 manual still be similar enough to use?

[action]

I
Would the 1977 or 1979 manual still be similar enough to use?

1979

The fifth gen Continental and Mark V ended in model year 1979. 1980 and later will be much different
The module change was a 1978 and tater thing. (Will be missing in 1977 publications)

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[Dan Szwarc]

I would definitely spend the $20 for one as that would be super helpful, but it looks like the 1978 one isn’t offered. Would the 1977 or 1979 manual still be similar enough to use?

Yeah, I don't have 1978. Only 77 and 79. Some parts of 75/76.

PM me if you send a payment. I don't always get notification emails from paypal.

[jakescervino]

It looks like the part I need is available on eBay again (https://www.ebay.com/itm/NEW-Motorcraft ... Swgm5dn743). However, it says it is for a 1980 Ford LTD 302 5.0L V8. Would this part still work in my 1978 Lincoln? Also, I still need to figure out where the vacuum line connects to. Where can I find a vacuum diagram for my car?

[Dan Szwarc]

The switch you need is the D8AZ-12A265-A PN or Motorcraft SW-1473. That ebay switch is one of the many similar, but not the same Ignition Timing Vacuum Switches for used in that time period. I think this is a 78 only part. 79 has a different PN because they were tweaking the carbs every year back then.

I just checked RearCounter.com and they have many of its siblings, but not the exact switch.

It may function just fine on your car, it may not. More than likely, you will not notice any difference.

I don't know enough about what this exact switch does. It's likely retarding or advancing the timing to help reduce emissions. There are so many because they are designed for each engine size and carb that was used.


Regarding shop manuals, the factory shop manuals are pretty bad for anything related to vacuum or electrical diagnosis. For that, you need the Electrical and Vacuum Troubleshooting Manual which was available separately and are much harder to find. There just happens to be one on eBay right now.

You may find it useful, but it may not solve your problem. It is a fantastic manual to have if you really want to learn.