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Vacuum port for distributor?
#1
Hi,

is it correct that the vacuum port in the picture below is for the distributor vaccum advance?

[Image: Unknown.jpg]

Thank you, Manfred
  Reply
#2
I've got mine plugged and ran my dizzy vacuum to the carb. Sorry I didn't answer your question, but heres a link that may:
http://www.mustangbarn.com/72vacuum.html
Find the vacuum diagram that fits your setup. Dual diaphram vs single etc...
Does your engine have a Distributor Vacuum Control Valve (DVCV) on it? If so, check out this link also:
http://www.stangnet.com/mustang-forums/7...-pump.html

Hope this helps you as much as your questions have helped me. I'm now thinking about making my vacuum system as close to stock as I can make it.
Thanks,
DJ
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#3
Yeah, this is the one that uses that port.
http://www.mustangbarn.com/images/vacs/7...vacuum.gif

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#4
markmel;34623 Wrote:Yeah, this is the one that uses that port.
http://www.mustangbarn.com/images/vacs/7...vacuum.gif

Awesome! I did a little more research and if you no longer have the DVCV on your water pump/neck, then you can either get one on fleabay for up to $69.99 USED Angry Or, you can get a new one with lifetime warranty from Borg Warner part# EC970 for $30+ or a cheaper replacement from STD part# PVS14. These are called "Ported Vacuum Switch" but exactly the same as Distributor Vacuum Control Valve (DVCV)
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#5
FasTnNefariouS;34611 Wrote:I've got mine plugged and ran my dizzy vacuum to the carb. Sorry I didn't answer your question, but heres a link that may:
http://www.mustangbarn.com/72vacuum.html
Find the vacuum diagram that fits your setup. Dual diaphram vs single etc...
Does your engine have a Distributor Vacuum Control Valve (DVCV) on it? If so, check out this link also:
http://www.stangnet.com/mustang-forums/7...-pump.html

Hope this helps you as much as your questions have helped me. I'm now thinking about making my vacuum system as close to stock as I can make it.
Thanks,
DJ

Thanks,

the vacuum diagrams really helped. I think [Image: 71%20351C%204v%20without%20dvcv.gif] best describes my setup since I have no DVCV and a single vacuum advance distributor. This means I will directly connect my vaccum advance to that port.

Thanks, Manfred
  Reply
#6
ManniB;34606 Wrote:Hi,

is it correct that the vacuum port in the picture below is for the distributor vaccum advance?

[Image: Unknown.jpg]

Thank you, Manfred
Manfred, That is a manifold vacuum port. Given the Accel distributor design, you can use that port. Chuck
  Reply
#7
c9zx;34634 Wrote:Manfred, That is a manifold vacuum port. Given the Accel distributor design, you can use that port. Chuck

Thanks, will do.

- Manfred
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#8
That should go to the DVCV on the water pump, to switch from ported vacuum to manifold vacuum at idle should the engine start to overheat. On a '72 351C, it also had a T-fitting to a vacuum control valve on the drivers' side valve cover. This was part of the IMCO system which would switch on manifold vacuum to the retard port on a dual-diphragm distributor (which I see you do not have) under certain conditions. I just run mine straight to the DVCV - I get the overheat protectiion without that power-robbing emissions crap.

As you say you have no DVCV and a single diaphragm distributor, you can use that port for full manifold vacuum to the distributor and plug the port on the carb, or use the carburetor port and plug that one. With no DVCV, only one vacuum source can be used.


Joe
'72 Grandé, 351C, Autolite 2100, FMX, 2.75
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#9
On that port it will increase your timing at idle (might vacuum at idle/cruise). Ported vacuum is the opposite, it will get higher as engine load in increased. You car will act differently depending which port you use. (and your initial timing and where you set it will be different). It's important to understand how each works and what it will do to the vacuum advance on distributor timing.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#10
Thanks guys, I understand (in theory) all your explanations about manifold and ported vacuum and what the difference is. What I still have to find out is which one to prefer in my situation.
I read in another thread (I even think it was on the other site) that, performance and mpg wise, manifold vacuum should be used and that ported vacuum is only for emission purposes.
I played with the ignition advance over the weekend but didn't get conclusive results. My idle is lumpy (term???) which I understand might indicate a vacuum leak.
My problem is, I do not know how smooth the idle can/shoud be since I don't have anything to compare it with. Engine rpm varies by 50-100 and the vacuum by 1-2 inches during idle at 500 rpm. If I set the idle to 800 rpm it somehow smoothes out. The engine has been rebuild 2000 ago but has been sitting for 10 years since then. However, I have installed all new gaskets before it went into the car. I think I will try the carb cleaner for leak testing (never did that before) and maybe take a video of the idle and come back for your judgement ;-)

Thanks, Manfred
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