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HEI vs. Duraspark TFI

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Rambler Mexicano View Drop Down
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    Posted: Feb/22/2012 at 7:00pm
Hello everyone,

I've been thinking over the last few months to replace the already modified yet crappy Prestolite distributor on my 282-six-cylinder VAM Rally GT for a different more reliable unit that also boosts up the general performance of the engine.

My first choice was AC Delco Chevrolet High Energy Ignition distributor, which is very common in VAM cars here in Mexico as a replacement part.

But,

While doing some research on the web and also with comments from people on the forum, I have also found the Ford Motorcraft Duraspark ignition system upgraded with the Think Film Integrated "TFI".

I would like to ask if anyone's experiencies with either of them, or both, and what would you recommend.

What I want to the highest possible performance now that I'm going to do the whole swap thing, I would like to do everything in a single try. Besides performance I also looking for the highest reliability.

Which is considered more reliable? (quality, durability, operation, etc.)

I've read the that the Duraspark with the TFI is supposedly 50% more powerful than the HEI. How much of this is true?

Is the TFI just the COIL or more parts?

Can the TFI be used in a SIX CYLINDER distributor or only in V8 distributors?

Can any of these be modified in the vacuum advance for higher acceleration?

Anything in particular I should know about any of them?

Thanks in advance.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DocCreer Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2012 at 7:08pm
Ok the hei will need to be recurved for use in a amc motor,the vacc advance isnt adjustable but a adjustable vacc can is avalible.the hei coil is weak.the hei is only one wire and very easy to install.The duraspark tfi system comes with an adjustable vacc advance,and is already curved for your motor.With the tfi cap and coil spark energy is greatly increased.its also a very reliable system,the only problem is that most aftermarker control boxes can simply drop dead with no warning,so its a good idea to carry a spare.

I have done both and have found the tfi a better system
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mramc Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2012 at 7:10pm
AMC used the Ford setup from 1978 up until and a little after Chrysler bought AMC . You need more part for the setup as it's distributor , control box , coil and wringing. The coil is clip on post type not the standard nut on stud type coil. The GM type HEI are all over the net and commonly used as upgrades for any of the stock AMC used distributors. They HEI style is both cheap and well regarded as a upgrade over stock. LRDaum 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2012 at 8:45pm
Quote I've read the that the Duraspark with the TFI is supposedly 50% more powerful than the HEI. How much of this is true?
 
My reply to that? So what if it is!! That is POTENTIAL only, you won't use it. If you put a system in there able to crank out 200,000 volts, so what? Your engine will probably only use 25,000 volts - more under heavy load. An ignition system builds voltage or potential until the gap is jumped, then the voltage drops off and the energy is used to keep it moving under much lower voltages. Much lower.
(frankly the 50% is a wild number - that's enough to burn holes where you don't want them, you'd never use that.)
 
The "my system is more powerful than your system" is mostly hype in ignition once it reaches the point of HEI. Anything more is wasted.
 
Sorry, doc but that's some BS you've heard about "the HEI coil is weak".
I've worked with HEI for, well, decades, since it came out. In fact, I was working with electronic ignition before most manufacturers moved that direction. IT's only weak in the insulation if you run a huge plug gap or have a bad wire, etc. - then she'll burn holes through the coil insulation, even the cap or rotor. It's hot.
 
Quote The duraspark tfi system comes with an adjustable vacc advance,and is already curved for your motor.
 
It is? How do they know what he's got?
IMO, you need to recurve ANY replacement ignition system for YOUR engine, the size, compression, fuel, gear ratio, needs.
 
Quote With the tfi cap and coil spark energy is greatly increased
Nope, the cap has nothing at all to do with it, and the coil is like other high-output coils, even the HEI coil. Greatly increased over what? Stock, yes.
 
No offense, but that's what I mean by hype and misinformation.
While I will not diss the TFI system, it is very good, the myths about ignition are far more common than fact. (as can be evidenced here)
 
IMO, it's personal preference after you get the facts - such as Larry stated about parts, simplicity, etc.
I've run HEI and it's far more spark than any little AMC 6 (or big AMC 6) will ever need UNLESS you have an engine that's tired or has physical issues. HEI has the ability to send more spark potential as well as duration than you should need. HEI style systems are running cars down the quarter mile strip under harsh conditions and high speeds.
 
HEI is the most "simple" way, if you decide all else is equal-  it's almost a drop in. You can grab a distributor from an 80s 250, put on an 80's AMC V8 gear, make sure the distributor doesn't bottom in the oil pump, might have to use a grinder and extend the flats up the shaft just a bit, other than that, drop it in, and power it with 12v from the ignition side of things. Don't run it through a resistor, give it a full 12 from the switch. I spent just about an hour putting mine int a couple of years back.
 
Some have a thing against most anything GM, and prefer the "Ford" style TFI system. They work, what can I say.  They are pretty reliable for the most part. IMO, so is HEI.
Does it put out more voltage? Maybe, but again, so what? HEI will burn holes in things - do you need more than that? No.
 
I guess it boils down to what you believe, and personal preference, and your leanings on brands, etc. Reliability? My HEI was bone stock, decades old, still worked perfectly. I guess that's reliable. The truck I pulled it out of was running on the second hundred thousand. So was the car I put it into. No problems.


Edited by billd - Feb/22/2012 at 8:50pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firefly Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2012 at 7:34am
I run the duraspark with tfi upgrade and use an MSD 6al for the box. It might be overkill,but I've never had any problems starting ANYTHING. On the other hand,I have a stock 258 Concord with an HEI setup and it runs great also. Personnal choice here I think.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2012 at 10:58am
  The problems i've encountered with the Ford system mostly has to do with the connectors.
  The plastic doesn't hold up well to under hood heat,  after awhile the quick disconnect part that is fleckible becomes rigid,  and breaks,  leading to a loose connect with corrosion inside, then the control box overheats and fails.
 
  I had one out of a 79 Spirit in my 74 Hornet,  and my J-10 had the Ford ignition when I bought it. I had the same problem with both.  Sold the Hornet,  put a DUI HEI on my J-10 maybe 8 years ago. 
 
  Only problem i've had with the HEI was my own fault.  I installed a new cap,  overtightened one of the coil hold down screws and it stripped,  that led to the other 3 screws working their way loose,  or I may have stripped more than one and not known it.  Anyhow loose coil hold downs = overheated coil,  and failure.


Edited by tyrodtom - Feb/23/2012 at 11:00am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2012 at 11:14am
As Bill pointed out, it's really six or one, half dozen of the other. Both work well and are great upgrades in their own right. You will be happy with either or that crappy Prestolite system! I don't know anyone who LOVES the Prestolite, though there are some who don't really have a problem with it. The factory had a connector problem, but once taken care of the Prestolite can be made to run reliably. I just don't like it.

If the GM 250 six is a lot more common down there than the AMC Motorcraft distributor you have your answer! The Chevy dizzy will drop right in the AMC motor (you can use a large washer under the distributor instead of grinding as Bill suggested, one will usually do the trick). I don't think the Ford 240/300 six distributor will -- you need an AMC six specific Motorcraft distributor. All the other parts are generic Ford though (cap, adapter, rotor, wires, coil, etc.).  As far as the snap on connector is concerned, you don't need it! Cut the wires and put ring terminals on -- problem solved!

The main difference between the two is that GM redesigned their whole distributor for high energy ignition (HEI) whereas Ford chose to adapt their existing distributor. Hence the need for the cap adapter (to mount the bigger diameter cap to separate the spark plug towers more) and the external ignition module.

There have been problems with aftermarket ignition modules for the Ford system. The easy solution is to wire in a GM HEI ignition module. You can just mount the GM module on any metal surface (must be metal so it acts as a heat sink) or put it on a heat sink (I've seen people use old computer processor heat sinks). Here is the really trick way to do it though -- mount it in an old Ford ignition module box! 
http://www.fordmuscleforums.com/ignition-articles/492810-tricky-trick-hei-module-inside-duraspark-case.html


Edited by farna - Feb/23/2012 at 11:15am
Frank Swygert
American Motors Cars Magazine
www.amc-mag.com
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