Vacuum advance or not? |
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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Posted: 14-April-2020 at 1:28PM |
I have seen lots of pics on the facebook groups that show distributors having no vacuum advance. What is the deal with that? Any benefit to it? Is it merely a fuel mileage issue? I picked one up for short money without an advance and it is probably going to be another paper weight.
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5846 |
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I personally would never run a distributor without a vacuum advance. What is the advantage to removing it on a street car?
Here is what David Vizard says about them:
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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Nice writeup. After doing a bit of reading, vacuum source (ported/direct) was mentioned more than a few times. Definitely not using a distributor without the vacuum advance. I might try direct manifold source for the heck of it.
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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so what is this potential paperweight, something i might be interested in? direct manifold vac requires another level of set-up and calibrating to limit the timing pull otherwise it can pull up to 60* or more at idle! some distributors are not easily capable of being limited with an allen key through the vac nipple because there's no adjuster inside. aftermarket replacement vac pods are/used to be available but i have no idea what the current state of availability is today? i have a link to a how-to but be aware if you're subject to epa testing the manifold vac system may not keep your CO's & HC's where they need to be. that's what the ported / timed spark vac source does, no vac pull at idle so no increase in CO/HC until the throttle blades activate the timed spark port. " The vacuum advance unit is adjustable. You need to limit the total
advance under vacuum. You adjust the unit by inserting an allen key (I
do not recall what size, try several until one fits) into the front
(some have two) hose nipple. Turn it one way or the other (been a while,
obviously) until total additional vacuum advance is about 10 degrees.
Your engine will like this. In my daily butt hauler I run manifold vacuum advance. The car is a 1973 Mercury Montego four door. It's a pretty big car, about 4200 lbs. The engine is a 351 Cleveland 2V, it has a PAW/SSI 11339 (194/204 @.05, .458/484), a Performer intake, a 600 Holley and duals. I use a Pertronix Igniter in a Ford dizz with a Ford Duraspark coil. The Holley has a light sec spring, so it cuts in quickly. I run 12 degrees initial advance, use the stock curve and use manifold vacuum for the vacuum advance unit which is adjusted to provide only 10 degrees additional advance. The result is that at idle, the engine runs smoother with the ac on (York comp that does not cycle, unless you count when I have to turn it off when the core freezes. I could store meat in that car). The vacuum provides an increase in efficiency at cruise (18 MPG with 2.75s). Being that it is manifold vacuum, the amount of additional advance is reduced when I push into the throttle. Acceleration is easy and effortless, especially in the 2-5K range where Clevelands run great. The greatest advantage of this set-up is the reduction of advance under acceleration. The US 2V Cleveland heads have an open chamber. That chamber coupled with the dished pistons of 1973 create a great deal of surface area. Detonation is a real problem here, but I am able to run the car on 87 octane with no problems, even on hot SoCal days with the AC on. When I was trying ported vacuum, I could get it to run well but detonation on acceleration was a problem. As it is, the car runs very well." ~ Tom Custom (founder of the original 351C forum) check out the new 351c.net Edited by Rockatansky - 15-April-2020 at 10:59AM |
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72 GT Ute
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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I suppose so. I haven't opened the box yet but it was cheap money, probably made in China.
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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I just opened the box. Pretty well built for the price.
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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the $40 Special, small diameter can be very useful in some cases not a Ready To Run type but requires some kind of module, can be used with a Duraspark box, GM module, Mopar transistor unit, MSD6AL etc. price of the ticket less than you'd think the housing alone cost, the biggest ? in my mind is what will cap & pick-up coil available be going forward? possible they are patterned on something existing but IDK what that is if anything?
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72 GT Ute
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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I hear you. Didn't even see there was no advance until I clicked buy. Tried to cancel immediaty. Zero replies. Typical online experience.
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5846 |
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What are you running now for a distributor? This is what I run. It's a lot more money, easy setup and works great:
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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I have an original with the Pertronix. The new one was shiny and I was like an ostrich. I habe been trying to return it with no success. I like your setup but don't you need other components as well?
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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Ready To Run is an industry term used to describe a 'stand alone' distributor like OEM, only needs a coil. Tim's dizzy's use a GM style Pertronix module
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72 GT Ute
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green 72
Member Joined: 27-April-2010 Location: Manchester,Iowa Status: Offline Points: 43 |
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I have bought several different ones from advance auto/carquest that are new units. have used both point ones and dura-spark ones . they are under 100 bucks and are really good distributors. they are like oem and even come with cap and rotors
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Dan 1972 GTS Formal
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handsofstone
Senior Member Joined: 13-April-2018 Location: Northeast Status: Offline Points: 3946 |
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I never had an issue with oem. Injust wanted to dress up the engine a bit and wasn't paying attention to the advance. I will put it on ebay or a parts page on farcebook and take a little loss. Won't happen again until next time. Haha
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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take your stock one and either sand and polish it or remove the advance and chuck it up in a lathe and machine what you can sand the rest
Edited by californiajohnny - 18-April-2020 at 9:06AM |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5846 |
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All it needs is a 12 volts of power, ground and a coil. I used an e-coil from a 5.0L Mustang. I used 12 volts through a relay, triggered by the original resistor wire. So far, it works great. I have the prototype distributor and Tim was using DUI modules when mine was made. Seems he has switched to Pertronix modules now. You can do a cheaper version of the same ignition, which is outlined in this thread here on Todd's Ranchero: |
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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Yes a Duraspark is just a magnetic pick-up unit, similar to MSD that requires a spark box. you can wire it up to a GM module, Pertronics etc. a stock points dizzy can trigger a 6AL box or probably anything else too. point gap is not critical at all as long as they make & break, no condenser IIRC, it just becomes a trigger unit. a stitched wheel from the hardware store on a drill motor and a couple compound sticks will buff up a stock housing. do yourself a favor and invest in a metal sealant so it stays nice ;) |
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72 GT Ute
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