[wolframkrill]

Can anybody tell me where I can find data for the OEM distributor on my '72 Mark IV? (D2VE)
I searched this forum plus the Ford maintenance handbook and couldn't find anything.
How many "Hg does it need to activate the vacuum advance mechanism? Around 15 inch Hg?
How many degrees does the vacuum advance, how many degrees does the mechanical advance pull?
How much is max. total timing?
I put on an Edelbrock 1406 on the car and take the vacuum from manifold. Where did the distr. took its vacuum originally on the Autolite 4300? Ported or manifold?
I do know Ford started crude smog measures this year, retarding the cam, etc.
Thank You all for reading this far, Martin

 

[The Mad Porter]

The ignition curve was emissions oriented and designed for use with EGR.
If you eliminated EGR you will need to dial back the vacuum advance.

Open chamber heads require more total timing than closed chamber applications. Your OEM unit does not supply enough mechanical advance and what it does supply comes in too late via a dual stage spring set up.

Hook your vacuum advance to the ported vacuum nib on the eddy carburetor after you dial back the advance.





Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
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[wolframkrill]

Thank You for the information.
I was afraid I had something with emission controls on the car, therefore the initial post.
I don't know if I had or have EGR on my heads, I can see nothing from the outside.
I had the vacuum control unit on the waterneck but it was already dead and not connected when I got the car.
The distributor has only one hose. I know from the Ford manual that there were versions with two lines, advance and retard.
Would it be a good idea to install an aftermarked distributor, just to make sure it works the full range?
Personally I believe in the benefits of manifold vacuum. I just don't want to change ports by chance without knowing what I do.
Thanks, Martin

 

[The Mad Porter]

EGR is a plate under the carburetor between it and the intake.
Dashpot introduces exhaust gas to cool chamber slowing flame front speeds and requiring more part throttle advance.
Not active at WOT.

A properly curved distributor does NOT benefit from manifold vacuum to the advance dashpot.
OEM and our recurved distributors run best with ported vacuum







Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine

 

[wolframkrill]

I guess You are right.
I seem to get insane values from the manifold port. With an initial of 10-12 degrees I read 25-30 degrees at idle with the advance hose back on and well over 50° at WOT?!
With ported vacuum the engine pulls nearly 15"Hg with 10° at 650 rpm, over 16"Hg when I go to 12 degrees advance. Is this o.k.?
Although I don't know if it will knock with so much advance? I should mention that I changed to a pre '72 timing chain set.

 

[The Mad Porter]

The 1972 open chamber D2VE castings need more total timing for best power / economy.
To be clear on definitions...

Total timing = Initial + mechanical.

Vacuum advance is a part throttle addition to mitigate the slower burn rate due to throttling and leaner mixtures.

A typical oem configuration 1972 429 with an early timing set and 180f t-stat will like:

14 to 16 initial
20 to 22 mechanical for a TOTAL of 38 degrees. All in by say 3000 to 3200 rpm

The vacuum advance with out EGR should be about 10 to 14 degrees additional at 14 to 17 inches vacuum.

Duraspark_distributor_recurve_instructions_index

Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine

 

[wolframkrill]

Thank You very much! This is the profound information I was looking for.
I heard that most SBC & SBF feel best at 36 degrees total. Good to know that my '72 heads need a liitle bit more.
What puzzled me was that Ford recommends 8 degrees initial, at best 10° with my timing set, and now You confirm my expierience that the 460 can well bear a little more at 14° to even 17° initial.
Again, I am very grateful for Your advice, we don't have many people with Your experience with BBF's around here.
Thank god I have no EGR, but what I did obviously have was that PVS valve as Ford called it. As to my understanding it was supposed to be a kind of bypass which switched from ported to manifold vacuum at high temperatures.
By the way: What is meant by "180f t-stat" ? The air pressure at a certain altitude?

 

[ArnoldRC]

180 degree fahrenheit thermostat for you, it'd be a 82 degree Celsius thermostat.

 

[PSIG]

It would make things a lot simpler if you disconnect vacuum advance temporarily for setting timing; then rev the engine to 4000 and set your total timing at 38°. Let it idle-down, set your idle speed correctly, and reconnect ported vacuum. Idle timing is whatever it is, based on original timing settings, modifications, wear or condition. Go from there.

An example of these unknowns is that you should not see 50° at wide-open throttle, ever, with your setup. So somethings not right in there.

Background is that idle timing was the factory procedure, with known factors and goals. Everything was new and unmodified (including emissions stuff), so it was done that way, back then. With all the unknowns of the engine in-front of you today, the only sure thing is where the total timing should end-up…38°. I agree with ported, as switching to manifold has benefits, but they require a new curve to maximize the benefits. In-fact, your distributor likely needs a new curve just to run best in any case. You're not doing either of those today.

 

[wolframkrill]

Thank You folks for all the input.
As far as I understand it the unknown factor is my 50-year old distributor.
I intended to replace it with a duraspace or MSD anyway. But first I wanted to understand how things work, and why, before I go shopping.

you disconnect vacuum advance temporarily for setting timing; then rev the engine to 4000 and set your total timing at 38°

I am going to do that while I am stuck with the OEM dizz, seems reasonable to me. Although I doubt if my trusty Lincoln will rev up to 4000 rpm Should be a hell of a noise.

 

[jiri.z]

Hello boys from Europe,
Thank for your profound information.
I have question for setting gap/rebound distributor contact? What gap is OK? I have new distributor and gap is very hi and all pistons not runing well
..and sorry for my english

 

[PSIG]

As far as I understand it the unknown factor is my 50-year old distributor.
I intended to replace it with a duraspace or MSD anyway.

Are you prepared for that? Just a reminder and not to be harsh but rather be helpful — that you are stuck trying to get what you have to work. OK. But with a change to DS or MSD, you will be throwing everything you have out and starting from scratch with a completely unconfigured generic setup. I only raise this point as you don't appear to have much experience to correct what you have, are not familiar with the implications of EGR or even basic ignition tuning, and it seems you are jumping completely off the boat to one that requires end-to-end configuration and tuning. So, again, are you prepared for that?

 

[wolframkrill]

You're completely right, I'm not prepared in a way that I am a skilled mechanic.
That's why I started this thread. I wanted to know what my distributor is supposed to do and how I can check what it is really doing.
Two weeks ago I didn't know altogether too much about manifold vs. ported vacuum.
Now I have learned from this forum a load of facts, about the beginning of emission controls on US Cars from the 70's, about the influence of advance timing on slow burning lean fuel mixtures and so forth. Great!
Of course I don't have the background here "out West" as You have in the States.
But isn't it part of the fun working on classic cars, that You can do it yourself? A guy can ask for advice and learn. And if I f*** it up - hey! - I'll start again!