VACUUM ADVANCE
#848575
11/08/10 12:33 AM
11/08/10 12:33 AM
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Joined: Dec 2007
Posts: 1,639
Brandon, Ms
cornet684me
OP
top fuel
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OP
top fuel
Joined: Dec 2007
Posts: 1,639
Brandon, Ms
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okay, please school me on the use of the vacuum advance on a elec. ignition dist., i am currently running a ready to run elec. dist. with a vacuum advance, i had to disconnect the vacuum advance due to a clearence issue with the dist., i have a slight blog , i have taken the vacuum advance off the dist., i had called the tech at skip white perf., he says that i can weld up the bracket so that the rod coming from the vacuum advance will hold the plate and i can cut the actual vacuum advance canister off the dist., what am i missing by doing this ?
this is a mild 1973 motor home 440/727, comp 268/454 cam, holley 750 vac. secondary, 3.55 sure grip in a 1968 dodge coronet
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Re: VACUUM ADVANCE
[Re: cornet684me]
#848576
11/08/10 03:32 AM
11/08/10 03:32 AM
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Joined: Oct 2007
Posts: 3,897
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,897
Oregon
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You'll just lose some MPGs if you do much cruising. Vac Advance is typically only used under light load, high vacuum situations to increase the timing, and squeeze a little more efficiency out. If you don't care about that, weld the arm and cut it off 
If you ever find yourself in a fair fight, your tactics suck.
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Re: VACUUM ADVANCE
[Re: cornet684me]
#848577
11/08/10 12:44 PM
11/08/10 12:44 PM
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Joined: Oct 2010
Posts: 606
Montana
Yancy Derringer
mopar
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mopar
Joined: Oct 2010
Posts: 606
Montana
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Quote:
................ due to a clearence issue with the dist................
If you have a clearance issue, "fix that." Either you have the dist. drive gear in wrong, or you need to move the plug wires around the cap one hole so that you can move the dist out of the way.
You can certainly remove the advance and braze the two plates together--otherwise there's nothing to hold the movable plate from flopping around free.
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Re: VACUUM ADVANCE
[Re: Yancy Derringer]
#848578
11/08/10 05:58 PM
11/08/10 05:58 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I'm with Ehrenberg, use it not only for the mileage gain but it'll keep your plugs cleaner. It's the last system you tune on a dist (after initial/total/springs) If you do pin it drill a small hole vertical thru the 2 plates & pin them w a mini bolt/nut w a spacer between the plates so they dont crush/tilt & b 4 you do that you can alter your rotor phasing (if needed) by idling it & w a 1/2" hole drilled in the flat of the dist cap halfway between the center terminal & #1 terminal, freeze the rotor tip like a strobe light on a dance floor and see if it is dead under the terminal (or close to it) or off to one side and depending on which side it is on (& the direction of rotation, you said BB right so CCW) you can shift it opposite the direction of rotation by activating the vac can with a vac pump until the phasing shifts closer & note the vac required then dissassemble the dist & pump in that amt of vac then drill the vertical hole to pin it at that location but note that the vac adv will shift the phasing & w it(the top plate w the magnet) being on an eccentric it will change the reluctor to magnet clearance so check that at the same time (.006-8) at the tightest vane (some vanes stick out a bit more than others). Have the dist loose & tighten the screw on the magnet base then turn the housing in a circle checking each rotor vane & find the tightest one & gap that one then turn the housing till the rotor is under #1 plug wire
live every 24 hour block of time like it's your last day on earth
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Re: VACUUM ADVANCE
[Re: Yancy Derringer]
#848579
11/08/10 07:02 PM
11/08/10 07:02 PM
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Joined: Jan 2003
Posts: 1,013
LEE, MASS
TOMRR
super stock
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super stock
Joined: Jan 2003
Posts: 1,013
LEE, MASS
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Quote:
Quote:
................ due to a clearence issue with the dist................
If you have a clearance issue, "fix that." Either you have the dist. drive gear in wrong, or you need to move the plug wires around the cap one hole so that you can move the dist out of the way. 
This works had the same issues
You can certainly remove the advance and braze the two plates together--otherwise there's nothing to hold the movable plate from flopping around free.
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Re: VACUUM ADVANCE
[Re: cornet684me]
#848580
11/08/10 07:48 PM
11/08/10 07:48 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
okay, please school me on the use of the vacuum advance on a elec. ignition dist., i am currently running a ready to run elec. dist. with a vacuum advance, i had to disconnect the vacuum advance due to a clearence issue with the dist., i have a slight blog , i have taken the vacuum advance off the dist., i had called the tech at skip white perf., he says that i can weld up the bracket so that the rod coming from the vacuum advance will hold the plate and i can cut the actual vacuum advance canister off the dist., what am i missing by doing this ?
this is a mild 1973 motor home 440/727, comp 268/454 cam, holley 750 vac. secondary, 3.55 sure grip in a 1968 dodge coronet
I wouldn't do this, i bought the ready to run dist. from Skip white Perf. for my 360, its a great unit, but the Mech. advance comes in much higher then they say, more like 3500, it has a lighter spring & a heavy spring, its going to run like Poo without the vacuum advance.
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Re: VACUUM ADVANCE
[Re: hooziewhatsit]
#848581
11/09/10 11:02 PM
11/09/10 11:02 PM
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Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
Rick_Ehrenberg
top fuel
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top fuel
Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
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Quote:
You'll just lose some MPGs if you do much cruising....<snip>
The real significance of this: Where's that unburned fuel going? Washing the oil off the cylinder walls!
You need a good 50-55 degrees total timing under light-throttle / cruise.
Rick
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Re: VACUUM ADVANCE
[Re: Rick_Ehrenberg]
#848583
11/10/10 12:06 AM
11/10/10 12:06 AM
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Joined: Oct 2007
Posts: 3,897
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,897
Oregon
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Quote:
The real significance of this: Where's that unburned fuel going? Washing the oil off the cylinder walls!
Huh, never thought of it like that  After 100,000 miles, that'd probably make a difference in the shape of the bore, compared to 100k with EFI.
On my 318, I have the vac can turned so it's pointing straight ahead. Otherwise, I can't get a ratchet to the hold down; had to use a wrench (annoying).
And when it's Properly tuned, you'll never know the vac advance is there 
If you ever find yourself in a fair fight, your tactics suck.
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Re: VACUUM ADVANCE
[Re: hooziewhatsit]
#848584
11/10/10 03:19 AM
11/10/10 03:19 AM
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Joined: Jan 2003
Posts: 277
Southwest, Mi.
74Cuda
enthusiast
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enthusiast
Joined: Jan 2003
Posts: 277
Southwest, Mi.
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The first thing I did was I take the distributor on my 440 Cuda apart and welded about .050 on the inside of the advance slots then changed the springs for full advance at 2800.
This will let me set the total advance at 34 degrees and have 16 degrea at idle. This got rid of my low end bog off the line.
Then set the vacuum pod up for 55 degrees of total advance at 55 mph. The plugs lasted longer, I got better mileage and the car ran a lot better.
Last edited by 74Cuda; 11/10/10 03:20 AM.
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Re: VACUUM ADVANCE
[Re: hooziewhatsit]
#848588
11/10/10 12:25 PM
11/10/10 12:25 PM
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Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
Rick_Ehrenberg
top fuel
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top fuel
Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
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Quote:
<snip>...I can't get a ratchet to the hold down; had to use a wrench (annoying)
Just buy a C-shaped distributor wrench, then it is a cinch! (K-D makes a nice 2-pc adjustable-angle one, too.)
Rick
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