Possibly silly to correct something that was written two years ago, but it appears that people are still referring to it, so:

That's backwards. The less load, the more vacuum advance. (I suspect the writer knew this perfectly well, and just goofed in the write-up.)

 

Hi and sorry to revive an old thread, but I have some news on this topic that many fe guys may find useful. I recently got a replacement dizzy at the zone for a 75 F250 so I would get a DS unit. It had to come from the vendor directly and is a new unit but when I opened it I found 10l and 13l slots on the shaft to my happy surprise. No welding required! I had asked for a reman warranty replacement and got this new one. The Mr. Gasket spring I used for the light spring replacement should complete the job. Have a great fe day,Kent.

 

nice thanks for the follow up

 

Great thing to know. I'm going to be replacing the distributor in my 76 soon hopefully I get one with the correct advance slots.

 

I just took a quick look at a link referred to us on the first page of this thread.

Quoting the foureyedpride.com article: (QUOTE) "Vacuum Advance: Most Ford distributors include a vacuum advance mechanism. This consists of a diaphragm vacuum canister, an arm from the canister to the breaker plate, and a hose connected to an engine vacuum source. The purpose of this mechanism is to provide spark advance when the engine is not spinning fast enough to create the centrifugal advance talked about earlier. In other words this is an engine-load dependent advance. This would be a typical situation when climbing a steep hill, or driving at low rpms, light throttle, conditions . . . " (END QUOTE).

The "climbing the steep hill" part is wrong, that's a high-load, LOW-vacuum situation. And what the author suggests as "the purpose" of the vacuum advance mechanism really isn't right, either. The point of vacuum advance is to give a lot of lead-time for the spark to get the fire burning in a low-throttle-opening situation when the engine is getting relatively low cylinder-filling, which burns slow.

Again, I'd guess the author knows better and just goofed; this is why you need to go back over what you assert online and edit it . . . maybe multiple times if you're like me!!

(EDIT) A caveat: the old Ford Loadmaster distributor (one came on my '66 Econoline 240) was a different kettle of fish, having a vacuum advance and NO centrifugal advance. Sub-optimal and best replaced with a good conventional dizzy (although the Loadmaster, being mechanically simpler, might have uses in racing, or with a computerized ignition that does all the advancing and retarding electronically and just needs the dizzy to send the sparks to the cylinders.

 

thanks Seattle - I thought the same thing.

 

Maybe the Reman distributor folks are wising up. The one I bought for a Y block was setup nicely. It's amazing what a .10c spring and the right settings can do. Definitely, have someone curve a distributor prior to installation if not certain it is correct. Somebody asked if this curving stuff is suitable for stock motors. Absolutely! Better fuel mileage, better performance etc.

Keep in mind when doing the arithmetic the distributor turns at half-speed so degrees are doubled - a 13L slot is equal to 26 crankshaft degrees for example. Get some timing tape for the damper so it's easy to read.

 

Where do you get timing tape for a 300 balancer? I've never seen any that are the correct circumference. I've been doing mine by hand with a set of dividers.

Link?

 

The main issue I've always run into with timing tape is that there is simply no where to put it. The thickest ridge on the balancer is about 1/4" or less.
At least it is on mine.

What I ended up doing was getting a file and putting nicks in it every 10 degrees up to 60 degrees. Line the timing mark up with 10 degrees and put a nick at 0. Rotate again to put the new mark at 10 degrees and put another at 0. Repeat repeat.
One of those little triangle shaped files worked really well.

 

I MARK MINE IN THREE 120 DEGREE INCREMENTS - 1/6, 5/2, and 3/4. Then I put a mark 30 degrees ahead of 1/6. That way I can use the 0 - 14 degree timing marks on the front cover for total advance: 30 + 4 on the cover = 34 total, etc. Very useful for ignition timing and setting valve lash very rapidly.

 

I have been trying to figure out what distributor to use for my 300 twin turbo project. The dual port canister looks like if you use just the front port you could get the advance to retard under boost? I know where you get the signal makes a difference. If someone has tried this and succeded I'd appreciate saving me time with the trial by error method. lol what does the weight of the truck have on how much the advance is?

Thanx
Terry

 

Hi Terry, my best suggestion for getting info on a dual port vacuum advance canister would be to search on forums related to the HiPo 289 engine used in Mustangs and a few Fairlanes. Ford used it for both advance and retard functions I believe and that dizzy didn't use mechanical advance (?). I am only aware of this as I have a 63 289 engine I am building with a duraspark dizzy, single vacuum port though. The little I know about turbos is from Engine Masters and timing retard is very important. I feel confident you will find lots of info on setting up a dual vacuum canister on HiPo 289 boards even though it will be NA, the info should point you in a good direction.

 

Thanx for replying

I found info on how Ford made it work in N/A aplications. 1969 Autolite Emission Control and Ford engine vacuum diagrams
page 27 has a diagram. The front port on the can is for advance and rear is for retard.

https://www.fordmuscleforums.com/thr...ibutor.443370/
this page talks about the 3 port vacuum tee.

I don't have a running vehical that I can put one of these dual port cans on. I currently have the 300 engine on a engine stand and the truck is a rolling chassis. I am in the gather parts mode. All these posts basically are trying to get rid of these parts(complex and outdated) and go to a single port advance. Nothing to do with boost. I think outside the box and wonder if there is a way to use the dual port in a boosted aplication. I ask to not re-invent the wheel but I seem to be one of the few that is always looking for a new and different way to do things. Sometimes it pays off..... From what I read they still have the mechanical advance. the vacuum works at low speed when the engine has vacuum. The mechanical comes in at a higher speed.

The Ultimate Duraspark Distributor Timing Guide.
Some of the articals have a list of different factory parts that give different amounts of full mechanical advance and springs to let the advance come in at a low rpm or higher. Quite the mass of info!

https://www.forabodiesonly.com/mopar...d-unit.179351/
this one they are hacking up a volvo unit and putting it on a Mopar dizzy.

I was hoping someone has alread when down this rabbit hole and turned around or made it through to the other side...lol I love to use factory part and try to keep it in the family. I have done hours of searching and would love any info or point me to to someone that has knowledge on this. please and thanx

 

I cant see running a dual port dist. as it is a smog part from back in the day.
I also have not seen any dual port dist. in a long time as they were used when EPA first started with smog regs.

Just get a single port, advance, dist. and re-curve it for your motor.
I just re-curved mine to stop the pinging and it works great.
Yes it was some work pulling it out of the motor, then pulling it apart to swap springs but worth in in my book.

BTW I wanted to replace the vacuum can because I was there but of the 2 I got 1 was not for the dist. and the other did not adjust like the factory one did so I just reused the one I had.
Dave ----

 

My very limited understanding is that timing retard is needed for turbo applications and that the amount of retard increases as the boost level increases. I know the blue grommet DS ignition modules have a retard feature for start up, stock it is wired to the starter solenoid S post but could be wired to be on for boost; it is a constant amount though not progressive as you need (I think). MSD module for turbo applications may be your only option.