Well, the good news is that the vacuum canister on the distributor currently in my truck is, indeed, adjustable with an 1/8" allen wrench.

Perhaps the reason the numbers do not match up with the 1982 date, which I provided to Gary, is that when initially converting to Duraspark, the salvage yard, where I purchased the distributor, said the donor vehicle was a 1982 [maybe it was 1981 or 1983?].

 

Yes, as said just now in the PM, I forgot that the truck is an 86. But I'd bet that the extra dizzy you have is an 81 version as the number matches perfectly to the parts catalog. (Not that I'll fight to defend the parts catalog, but on Calibration Codes it probably had to be accurate.)

So, we have two adjustable vacuum advance units (cans ). That's good as we may find the one in use now won't give as much advance as the engine wants, so it is good to have options. IIRC we can cut the stop on those to allow more advance if needed.

 

I just love it when a plan comes together!

 

Crane advance units use a 3/32 long shank allen wrench.
If stock units are already adjustable there's no need to order a new one.
I'd still be interested to see if a Crane can will fit an I-6 distributor.

 

We will check when David's here to see if my Crane unit will fit, just for reference and future use. I guess I need to start creating the to-do list in Evernote or I'll forget that bit. In fact, it would probably be a good idea to post it here so's y'all can help flesh it out and re-order it.

 

Look at the tags on this thread, it's an example of why I delete many of them:

https://www.ford-trucks.com/forums/1...how-to-11.html

 

I only see one: I6 distributor rotation. And we did discuss that. What am I missing?

 

You are somehow missing this, I'm guessing you're not looking at the thread I pointed out?


<table class="tborder" width="100%" align="center" border="0" cellpadding="6" cellspacing="1"> <tbody><tr> <td class="thead"> Edit Tags
Tags </td> </tr> <tr> <td class="alt1 smallfont" id="tag_list_cell">1986, 460, conversion, duraspark, f150, flathead, ford, georgia, i6, ii, parts, picture, plugs, spark, upgrade, vacuum </td> </tr> </tbody></table>


https://www.ford-trucks.com/forums/1...how-to-11.html

 

Missed the link on this phone. Obviously those tags are mainly worthless.

 

FWIW, I've just bought a new vac advance for my truck (V8) through Rockauto which also specified 'advance starts at 5" vacuum'.

I plugged a gauge onto it & applied vacuum; full advance was in by 9" Hg....+ or - depending on adjustment.

 

So, when we map the curve on David's vacuum advance we shouldn't be surprised if it is all in by 10". And, we should map the vacuum at the port on the carb to manifold vacuum.

But, did yours actually start at 5" Ken?

 

I don't remember, Gary.....I'll look again tomorrow.

At the time, I was just checking that it was fully advancing below idle vacuum.

 

Not to worry, Ken. We will map his and know for sure.

 

The arm is not truly tangential.
I'd imagine the action is not linear either.

 

My first thought was to map the actual travel of the arm vs vacuum, but then I realized that it doesn't matter as it might not be linear. And your observation explains why. So we will just use my Mityvac and map it every 1" of vacuum, but will tee the vacuum gauge on my diagnostic machine in as it is much larger and reading it will be a lot easier.