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I believe the adjustments on vacuum advance cans do limit advance. I could be wrong here but I've experimented with lots of advance curves. The allen adjustment limits the travel of the diaphram which limits the advance. Not all cans have the adjustment. I have modified several of them to reduce from 20 to 10
For a mild to medium 400 Ford This is what I have found to work well.
Get rid of ported vacuum, emmision controls (they don't really work anyway) Use full manifold vacuum
Initial of about 10/14 Vacuum of about 10 ( this will yield 20/24 at idle) Centrifigal around 25
For a "total" advance number of 35/39
Lean to the higher number if you live at high altitude
WOW!!
This distributor is NICE! I can tune to every rpm between 400 and my rev limit of 4500. My timing varies from 22 deg BTDC at 600 rpm and 50 degrees at high rpm high vacuum.....like deceleration.
WOT timing is variable too based on rpm. but typically, between 36 and 40 degrees. I could play with my timing tables all day long and they are so easy to change between dozens of tables. Cold start, hot start, hot weather, cold weather, torque table, hp table etc.
I advanced motors timing beyond what should be acceptable at 42 degrees locked out and no detonation, but torque sucked. I like torque so timing is optimized for torque in 40-degree weather right now. Did not even bother tuning a couple days ago with it was 22 below zero.
Now I know a lot of you commented on the tune for the factory carburetor. So, I will be taking the Innovative AFR gauge out of my Supercharged V10 excursion to dial in the AFRs for this motor.
Here is something I have found that most folks miss when it comes to our factory carburetors.
Notice the vacuum type diaphragm on end of solenoid? Item 1 ITS VERY IMPORTANT
Item 2 the solenoid see below is NOT ENOUGH YOU HAVE TO HAVE ITEM 1 too.
They way my system operates.
The solenoid only activates when the AC is on, so the solenoid is an AC kick for RPM when the AC is running. That is all it does.
Item 1 the diaphragm that attaches to the front of the solenoid is used to slow the throttle return so the automatic transmission will not kill the motor when the throttle is abruptly let off of. Its only job is to slow the return of the throttle and without it you will think something is wrong with your carb set up due to the motor dying constantly when you load it hard and then let off the throttle.
I adjust my ITEM 1 thingie by turning on AC, seeing solenoid click out the plunger, and adjusting the solenoid assembly to the proper AC in gear RPM. Then after turning off AC it clicks back.
Now you will be able to see how the diaphragm works as it slows the last 1/8" of throttle when the throttle lever is quicky actuated.
Without using this device, a fella would have to ignore factory idle data and set the idle to probably 750 or more to keep motor from dying. I would bet most fellas do that. The only problem is the vacuum advance port that is supposed to have zero vacuum at idle will have vacuum at 750 rpm because the throttle blades are too far open.
I have no clue how aftermarket carb manufactures deal with this issue but for my OEM carb this adjustment was the second-best thing I did to the bronco. First being the computer-controlled distributor.
I think only automatic vehicles have this diaphragm. However, I have no clue if its on manuals with AC or automatics without AC. I just know the above is how mine operates. Automatic with AC.
That distributor is pretty neat. I wish they made a box that could work as an add on for an existing ignition system but I didn't see that on their website. There are many different styles of throttle kickers and dash pots. There are even some dash pots with a vacuum hose that allow the throttle position to move farther closed when the engine is shut off to keep it from running on.
Yup, thats how I thought mine worked. Releasing throttle to prevent run on. Quickly found out it was not because I spent 2 hrs trying to tune out a carb that had a dying motor after a loaded throttle snap. Set throttle solonoid for AC and bam, no more dying.
My bronco is timed at 500 rpm and with throttle that closed I've nevet had no run on issues.
My advanced timing setting pushs idle up to 600 with no vacuum on spark port so all good there.
Pretty happy so far. 34" super swamper tires will spin a little in gravel with stock 3.50 gearing. Add in a 20% loss of HP and TQ at my elevation and that's pretty impressive on a all stock 400.
One other thing about this distributor that I have found nice.
No more standing in front of a vehicle trying to time it or unsafely putting on parking brake to see how the timing reacts in gear.
I can sit in the driver's seat and apply brakes, turn on AC put in drive, N, or reverse all while looking at my smart phone and making changes to my timing from my phone via Bluetooth.
I can have wife drive at 55 mph down the road and look at my phone to see what the timing is doing at that rpm and load. I can dial in more or less timing at that load and rpm and see how it reacts on the fly while she is driving. THIS IS INCREDIBLE!
It is like having my hand on the distributor and turning it as I drive down the road......
Yes
crank timing is set to 10 degrees but you could go to TDC (0 degrees ) if you wanted.
you can also fake the distrubtor out by setting base timing at 0 and let distributor think it's at 10 deg. And vise versa if you want more or less timing.
you just have to remember that all timing data will be off by that amount.
When working on the old ford make sure the vacuum advance canister has a fresh diaphragm I would suggest just replacing it vs testing with a vacuum tester so its not stiffened up, The accelerator pump diaphragm in that 2150 both of those when stiff and old can cause all sorts of sluggishness, stumbling and issues that appear to be timing.
What computer controlled distributor on a 79 bronco with no vacuum advance? (as stated above)
God help us
Post a picture so we all know what we are talking about
That is trick indeed
Borderline too trick
So you used the app and wrote the program for the timing and all is not well?
Hopefully it be warmer soon so you can reset the initial to 14 or so?
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