312 Distributor/vacuum question

[ECODE70D57FORD]

     My 57 Ford 312 engine has the stock distributor and factory dual quad intake manifold.  I will be running two WCFB carburetors.  I know that Ford distributors take their vacuum from the carburetor and not from the intake manifold.  It seems that GM distributors do not get their vacuum from the carb.  Does someone out there in the Y Block world know how I can get correct vacuum to my stock distributor with WCFB carbs? 
I know that there will be some out there that will say I should use stock carbs, but I am forced to work with what I have for now.  Thanks in advance 57 fordforever members for any answers that I may receive.
Jay in Mass.

[Oldmics]

The "E" code carbs are setup to allow vacuum from a ported orifice off of the venturi to tie into the distributor for the distributors vacuum advance.

Additionally the two carburators are tied together via a balancing tube that is on each carb.

Its truely a delicate balancing act.

You might be best just setting up the distributor for mechanical advance only and forgetting attempting a vacuum advance using the Carters.

May I inquire as to why you are not using the original carbs?

Oldmics

[ECODE70D57FORD]

Oldmics

     Thanks for taking the time to answer my question. 

     When I found my car about 10 years ago, it was in advanced stages of derelict condition.   It was stripped, needed the usual lower body panels and the roof was stomped in.  From the firewall forward, the only pieces that I could salvage were the nuts and bolts and the hood hinges.  The front sheetmetal was replaced with very nice pieces from California and Arizona.   I felt that I had to restore it because it is an E code  business coupe.  The factory dual quad intake manifold minus the carbs was found under some trash in the back along with some other parts.   I rebuilt the 312 and hope to start it this coming spring.
 
    Since I did not have the correct carbs, I just used what I had in stock laying around my garage.  These will have to do for now because I  still have a ton of work to do on it.   After I sell my 34 Ford three window  coupe, I will have some extra cash to put into it.  As you know  this is a very expensive hobby that we are in. 

     If everything goes well, even if it is not finished, I hope  get to take it for a test drive in the late summer of 2008.

Jay in Mass.  

[JimNolan]

Gentleman,
   I've read the thread and I'm confused about how the vaccum advance would work off of the manifold. My vacumm advance ( 390 ) comes from the carb. It has no vaccum on that line at idle. The manifold would have @ 18 inches at idle. How could you use the manifold vaccum to operate the vaccum advance of the distributor. The mecanical advance mentioned is the ONLY way I could see it working. The vaccum advance on the distributor should give it @ 10 degrees at first and then the rest of the advance ( to @ 36 degrees ) comes from the mechanical advance part of the distributor anyway. With 18 inches vaccum the vaccum asisted distributor wouldn't have a vaccum advance would it.
Jim

[Hoosier Hurricane]

Jim:

Here's my theory.  Set the timing with the vacuum advance unhooked for the total advance you want.  Then hook the vacuum to the manifold.  Most engines like this much advance at idle.  Now, at idle and part throttle operation you have lots of advance.  Good for emissions and gas mileage.  When you floor it, manifold vacuum drops off and you run on the centrifugal advance.  Won't exceed the total until the engine nears full rpm, at which point it probably won't hurt unless you drive for 30 miles at wide open throttle.  If the engine bucks and runs rough at part throttle cruise, you'll need to take a little of the advance out.  Some early vacuum cannisters have a removable hex nut where the vacuum line hooks on, and inside is a spring and some spacers.  These can be used to tune how fast and how far it advances.  On the ones that have no adjustment, you'll need to fabricate something inside the distributor to limit the movement of the point plate.  Hope you can figure out what I'm saying.

John

[JimNolan]

John,
   I understand what you're saying and see how it would work. I don't think it would be an ideal setup but it may work. Please correct me if I'm thinking wrong.
   1. I have an inital advance of 6 degrees. It will start easy at that setting without excess spark knock when the vaccum advance starts pulling in. I run 9.5 pistons.
   2. I have a vaccum advance that moves the distributor plate @ 8-10 degrees at a progressive rate when  opening the throttle plates. That's about 16 degrees total not counting the mechanical weight advance.
   3. When I accelerate I have a mechanical advance of an additional 30 degrees ( 15L weights ) that would give me a total of 46 degrees flat out advance.
   MY 390: If I try to run an inital advance higher than 10 degrees you'd think the engine was comming apart with all the spark knock I get during acceleration. So, that being the case if we set up the car like you're talking wouldn't you have to retard the initial avance to TDC before you could feasibly pull out without causing excess spark knock. And then wouldn't the engine be about 6-10 degrees shy of optimum advance for all out acceleration.
   My understanding is that you have initial, vaccum and mechanical in that order. Also it's my understanding that the total advance is all three added together.
   Let me know what you think, you're the bonified expert. And I mean that in a very complimentary tone. Jim
   

[shopratwoody]

I can't imagine any engine running at 46 deg advance on purpose?!
Ron

[JimNolan]

Ron,
   Would the vaccum advance which is approximately 10 degrees take up a portion of the 30 degree mechanical part. In other words: 6 degrees initial, 10 degrees of vaccum and then 20 degrees of mechanical advance to give a 36 degree total.
    If that were true, the vaccum part could be disconnected and the total would still be 36 total advance. From what I've read the 15L weights equal 30 degrees. Help me on this, I don't understand all I know about the distributor. Jim

[Hoosier Hurricane]

Jim:

In your first post, I didn't realize you had 30 degrees mechanical advance.  My theory then is wrong, as was stated, 46 total is too much.  At part throttle, you get vacuum on the carb port, but do you still have vacuum at WOT?  I'm not too sure of the ported vacuum system, but if it gives you vacuum at WOT, you would have way too much advance.  Your best plan at this point would probably be to unhook the vacuum advance.  I don't know how much total a 390 likes.

John

[JimNolan]

John and Ron and Jay,
     I believe I understand what's happening now. I have my distributor on the 15L slot giving me 30 degrees mechanical advance. That's why my engine pings so bad when I set my initial timing at 10-15 degrees.
     John's got to be right.  I loose the vaccum advance at WOT. I only have it at first acceleration. I need to limit my mechanical advance to 20 degrees ( they're adjustable ) and run an initial of 12-15. That would sure help me on low end performance too.
     So, from what you guys say and I've been able to read this is how it works.
1.  You set an initial timing where the engine cranks good and idles smoothly. ( 6 )
2.  The vaccum advance pulls the breaker plate around advancing the spark on initial accereration. ( 6 + 10 )
3.  The vaccum advance part drops off as the speed picks up and the Mechanical Advance ( 30 ) then takes
     over.  ( 6 + 10 - 10 + 30 = 36 total )
Jay,
   Back to your question. I'd do like John said to begin with. Bump up your initial timing to say 15 degrees ( as long as your engine will crank OK ) then let the mechanical advance do the rest. Worth a try. If you have a single breaker distributor like I do, go to www.bob2000.com/dist.htm and see how to adjust the limit of your distributors mechanical advance. Apparently you have to limit the TOTAL to around 35 degrees. I didn't know that. Jim

[shopratwoody]

Jim,
I don't know what a 312 likes as far as total adv. I have'nt had one for a long time.
In race tune up my FE's liked 38 total. The main thing is don't let it rattle (ping).
It won't last long like that.
good luck, Ron

[ECODE70D57FORD]

John
    Thanks for the good advice.  I will tweak that distributor as you suggested.

Ron 
     Nope....I will not let it rattle/ping.   My Y block will not like that.

Jim
     Thanks ... and will keep that bob 2000 link you sent me just in case I can't get it straightened out

Oldmics
      Yours will be the first one that I will try.

Jay in Mass