ignition systems
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Freshman User
Joined: Feb 2001
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ignition systems
Hi folks. I am pondering on what to do with my stock ignition system on my 71 Ford F250 360 ci. I would like some unbiased, experienced, non commercially endorsed opinions.
My question is this. Do you think a transitorized long duration inductive system is better/worse than a single spark CDI system for my truck's stock setup? How bout against a multi spark CDI system?
I'm kinda under the impression that manufacturers have us brainwashed into thinking we need all this electronics and that it will perform h.p. and mileage miracles.
Thanks
Cargo Master
Joined: Jul 2000
Posts: 2,281
Likes: 18
From: Northern California
ignition systems
I upgraded to the Pertronix in a stock dist with Pertronix epoxy coil, it works great. I've heard mostly good about the Omni setup from Jacobs but I understand it requires a special setup to work with the ford setup, http://www.fordmuscle.com/ did a review and it didn't impress me. Others say they are great and increase MPG by 1~3 I've heard better about the crane Hi6 and others.
I bought the Pertronix because it's $60 and the others were in the $400 range and I didn't think it was worth the extra cash, but I'm open to giving it a try later. Jacobs is supposed to have a new setup for Fords soon, that might be worth a look. Either way, the upgrade from points is well worth it. A stock Duraspark from the 75/76 is also a good simple upgrade.
I bought the Pertronix because it's $60 and the others were in the $400 range and I didn't think it was worth the extra cash, but I'm open to giving it a try later. Jacobs is supposed to have a new setup for Fords soon, that might be worth a look. Either way, the upgrade from points is well worth it. A stock Duraspark from the 75/76 is also a good simple upgrade.
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
ignition systems
I myself like the MSD system. Most people are very happy with the Pertronix units, and if $ is an issue I'd go with that. I have the MSD distributer, off-road 6T box, SS blaster coil, and 8.5 superconducter wires. Do you need all this stuff? Naw. But my system is rock solid, fires immediatly when cold, horse has improved as has mileage, along with throttle response. Just my nickles worth...
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
ignition systems
mad, a healthy electronic ignition will make a world of difference in how your engine runs. If you are looking to save $$ the pertronix is very tough to beat. If you don't run the pertonix, the duraspark dist. is the way to go, the one you want is from a 75 or 76 360/390. All of the aftermarket distributers are a waste of your $$. Be sure and run a vacuum advance, plumbed to full manifold vacuum, or your gas mileage will not be there. I find the duraspark control boxes too complicated to bother with so my duraspark is wired to an LX101 box from standard motors, intended for a chrysler it has only five wires. I got the instructions on how to wire from Jacobs electronics, and ran their coil # 380672. After reading Mr Jacobs text book on ignitions, and learning more about how ignition works than I ever wanted to know, I added a Jacobs computer to the above setup. I am very happy with it and have no troubles or complaints. I run a 080 gap and have no misfires or hesitation, ever. DF
Freshman User
Joined: Apr 2001
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ignition systems
I got a reman for a '76 F250 Duraspark and a box for an '84 460 F250. I also got the vacuam advance (the distributor cam with a very strange twin port vacuam advance that put way too much advance in) a big cap and 8.5 wires for an '84 460. The vacuam advance is adjustable, BTW.
It had a 13L centrifugal arm. All I had to do was put lighter springs in to bring it all in by 2250.
It works great.
It had a 13L centrifugal arm. All I had to do was put lighter springs in to bring it all in by 2250.
It works great.
Senior User
Joined: Jan 2000
Posts: 238
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ignition systems
I have always been under the impression that you should run the timed port for the vac advance. Whats all of yalls proffesional opinion? What kind of difference will it make?
Dave
http://www.davesmonsterpit.com/dmp31.gif
Dave
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Elder User
Joined: Oct 1999
Posts: 917
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From: Kelseyville USA
ignition systems
Dave,You Write... >>I have always been under the impression that you should run the timed port for the vac advance. Whats all of yalls proffesional opinion? What kind of difference will it make?
Dave<<
YES.. the timed port is the correct way to run the vacuumn advance.
Using constant manifold vacuum for the advance will pull the advance to full advance at idle.. That can cause overheating etc....
If you set the initial advance at ..say 12 deg and then get say..14 with vacuum thats 24 at idle with the engine running.
WAY toooooo much....
My .02
__JOHN__Õ¿ö
FTE Club #7
Member-
http://www.cruisin-north.com/
Santa Rosa, Calif.
72 F-250
ICQ#6030753
http://www.ford-trucks.net/users/jbhf250/
https://www.ford-trucks.com/pictorial/big/1972_f250_2.html
Dave<<
YES.. the timed port is the correct way to run the vacuumn advance.
Using constant manifold vacuum for the advance will pull the advance to full advance at idle.. That can cause overheating etc....
If you set the initial advance at ..say 12 deg and then get say..14 with vacuum thats 24 at idle with the engine running.
WAY toooooo much....
My .02
__JOHN__Õ¿ö
FTE Club #7
Member-
http://www.cruisin-north.com/
Santa Rosa, Calif.
72 F-250
ICQ#6030753
http://www.ford-trucks.net/users/jbhf250/
https://www.ford-trucks.com/pictorial/big/1972_f250_2.html
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Freshman User
Joined: Apr 2001
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ignition systems
In my case the opposite is true on overheating. My cam is on 106 center, and will run warmer on timed than on manifold. The reason is afterburn. The later timing causes more of the mixture to still be burning when the exhaust opens. The use of the timed port came to be in the emissions era to reduce emissions because of this. Using the maifold port on the carb was generally accepted, and even most OEM applications used it before 1970. In that era dual port canisters started showing up.
All engines have different needs, mine prefers maifold ported vacuam.
All engines have different needs, mine prefers maifold ported vacuam.
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Logistics Pro
Joined: Feb 2000
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From: Sun River St. George
ignition systems
Ported vacuum is taken from above the throttle valve. Manifold vacuum is taken from below the throttle valve. Distributors use ported vacuum. With ported vacuum there is no vacuum signal at idle. Pertronix works like a bear. Starts hot or cold runs smooth, accelerates without sputtering, fuel mileage is improved. I use a stock 390 60"s vintage distributor , ported vacuum, long rotor, adapter and big cap, 8mm fat wires, autolite platinum plugs gapped at 60, Mallory blaster something crap coil. Edelbrock 1405 out of the box. Advance the timing until it knocks under load then back off until it don't. Run it for about 10,000 miles without screwing around with it. I did. Going strong every day.
William in Atlanta
William in Atlanta
Freshman User
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ignition systems
The distributor can use either. I have found many engines that work better on manifold vacuam. The advance is needed at idle and cruise, not under load. Ported can stay on long enough to cause a little ping before it falls. Manifold drops immediately.
If you have a cam like mine (106 LCA) you can actually see higher operating temps, enough to percolate the fuel out and cause dieseling. Just the opposite of what is expected since I'm seeing 27 degrees of timing at idle (12 initial and 15 in the can) The manifold vacuam actually works better at cruise because it doesn't hang on like ported.
If you have a cam like mine (106 LCA) you can actually see higher operating temps, enough to percolate the fuel out and cause dieseling. Just the opposite of what is expected since I'm seeing 27 degrees of timing at idle (12 initial and 15 in the can) The manifold vacuam actually works better at cruise because it doesn't hang on like ported.
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
ignition systems
Dino, I'm kind of surprised you advocate for the vacuum advance. I agree that there is no need to spend $ on the after market distributers, but I don't believe mechanical advances can be beat for tuneability and power, its one of the reasons I got the MSD unit. Your absolutly right about vacuum advances and mileage of course. Guess it all comes down to what your preferences are. Just a comment...
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
ignition systems
Okay, I should have been more clear, use the mechanical advance that your dist already has, and the vacuum also, plumbed for full manifold vacuum. Port vacuum only exists because ford was trying to find ways to reduce emissions of oxides of nitrogen. They came up with some goofy setup that gives no advance until the engine starts to overheat, then a thermocouple of some sort lets the advance work. Mechanical + Full vacuum is the way to go. Ported vacuum is WRONG! don't do it. DF
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
ignition systems
Well I'll be dipped. I didn't even know you could run both types at once. I've only seen the stock distributers with the vacuum set-up, and then the aftermarket or stock hipo distributers with the mechancial spring set up. On my vacuum advance dists. I'd always run full vacuum and never understood the whole timed port crap. First time I've heard an explanation for the theory- thanks!
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
If your knuckles ain't bleeding you did something wrong.
'72 F-250 "Hi-Boy" 4x4, Dana 60/HD44, FE390 @ 400hp(purt near!), 4-speed, custom suspension w 4" lift, mud on black.
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
ignition systems
Actually, ported vacuum by itself has been around as lot longer than emission controls and it works fine for stock vehicles. The goofy setup DF mentions came around in the late ‘60s to reduce NOX. It allowed ported vacuum to the distributor only if the vehicle was moving 25mph or higher OR the outside temperature was below 65 degrees. There also was a temperature switch that allowed full time manifold vacuum to the distributor if the engine temperature went above 230 degrees.
Barry
Barry
New User
Joined: May 2001
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ignition systems
There is only one reason you should be using ported vacuum. This is because ported vacuum increases as engine speed increases. This, in turn advances the timing, which is needed as the engine speed increases. Using manifold vacuum is incorrect, for the simple fact that as the throttle is pressed, the manifold vacuum drops to near zero and provides no advance. A properly calibrated advance curve is worth a lot of power, and there is no way that a curve will be smooth with manifold vacuum, even if the engine works OK on manifold vacuum. If you can imagine driving at highway speed and then stepping on the gas. The ignition is at full advance and then all of a sudden, as the gas is pressed, the manifold vacuum drops, and the ignition retards several dgrees, just as the engine speed increases. Not a good idea.
As far as electronic points, in addition to Pertonix, Crane also makes an electronic points kit called XR700 and it simply replaces the points inside the distributor. It is compatible with the Crane HI-6 ignition too, which has all the features of a higher priced MSD unit.
As far as electronic points, in addition to Pertonix, Crane also makes an electronic points kit called XR700 and it simply replaces the points inside the distributor. It is compatible with the Crane HI-6 ignition too, which has all the features of a higher priced MSD unit.