what are the pros and cons of putting on an hei distributor. its going on a stock 351 modified. thanks for any info

 

I bought one of the ones they sale on ebay for about 100$.I put it on a 302.It worked great,but it is really big.I had a holley four barell also and I had to get a different air cleaner.
I sold it and the carb,and intake on ebay after I installed the engine in an fuel injected truck.

 

HEI simplifies the electricals slightly. HEI has no better performance than a stock DS-II system. HEI increases starter load over a DS-II system due to no start-timing retard. Both systems are easy to get parts for and to get tested. The DS-II system is easier and faster to get a replacement distributor for to get you back on the road.

 

What worked really well on my 390, was a duraspark distributor and an aftermarket ignition box with a magnetic pickup input. I got a duraspark distributor, Crane HI-6 box, and an LX-91 coil. I recurved the duraspark distributor for my motor and installed it. It works really well, better than the points ever thought of working.

I just cant see putting a Chebby looking HEI on a Ford motor.

 

A good, custom curved distributor does not need the start retard feature.
We offer both the D.U.I.(HEI) and custom curved Durasparks.

Please see:


http://www.performancedistributors.com/forddui.htm

 

Thought you might find these interesting:

H.E.I. DISTRIBUTOR MYTHS

Myth 1: Inductive ignitions, like H.E.I.-High Energy Ignitions, are not as good for high performance engines and racing motors as CD-capacitive discharge ignitions.
This myth is only true when compared to stock HEI systems. Today, we are making high output modules and coils that saturate fast enough to fire constant at high rpms. This firing ability also allows wider spark plug gaps-we suggest .050”-.055” with our D.U.I. distributor. The benefit of wider plug gaps is a more complete burn of the fuel mixture.

Myth 2: Internal coils(in-the-cap) over-heat.


This is probably the oldest HEI myth of all. First, HEI coils only draw 2 to 3 amps, compared about 6 amps an external oil filled coil draws. The lower amperage draw results in a much cooler running HEI coil.


HEI Coils also run cooler because they are encapsulated in thermal epoxy, which dissipates heat more efficiently than oil filled coils. The solid epoxy, in comparison to oil filled coils, eliminates the possibility of leaks.


You can also lose some spark intensity when you run a coil wire to an external oil filled coil-the spark has to travel a longer path of resistance.


Myth 3: Billet distributor housings are superior.


There is no benefit to a billet distributor housing in terms of better performance. Castings are stable and straight. Bronze bushings, utilized in our D.U.I. distributors, which are oil impregnated are extremely durable.


Myth 4: “A stock H.E.I. will do a good job for low to mid range rpm performance motors.”


The advance curve on a stock H.E.I. is not fully advanced until 4000-4500 rpm, which is very slow. If you low end cam power band begins at 2500 rpm(or below), then your advance curve will not be matched to your camshafts power band which will result in a significant horsepower/torque loss.


In addition, low to midrange performance motors(and even stock motors) benefit from a more intense spark from idle, all the way up the entire rpm range as the fuel is burned more completely.


Myth 5: “Vacuum advance adds power.”


Vacuum advance does not lead to more horsepower. Vacuum advance immediately begins to decrease as soon as you accelerate, and at wide open throttle there is NO vacuum advance. However, we do recommend connecting your vacuum advance hose to direct manifold vacuum because it will provide you with more vacuum advance at idle which will help to keep your plugs cleaner. Some motors will idle too fast/rough at manifold vacuum, in which case you will need to connect your vacuum advance to ported vacuum.

Myth 6: “There is a specific #1 terminal on the distributor cap.”

As long as you are at top dead center on the compression stroke, it does not matter which terminal you use as your number 1.

Myth 7: “Because this is a high compression high horsepower motor, use solid core plug wires.”

HEI systems run better with “spriral core” plug wires. The spiral core prevents internal wire vibration and prevents electronic interference.

Myth 8: The silicone grease you place under an HEI module insulates the heat.


No, in fact, the silicone transfers the heat produced by the module to the distributor housing. In effect, the HEI housing becomes a heat sinc.

 

The start-retard just removes some load and current draw from the starter, useful for starter longevity and for hot starts, nice but not always required. It can often help in some high temp applications with headers etc.

Epoxy encapsulation is better for high vibration applications in preventing wire movement and insulation wear. In normal operation even without external vibration the wires in a coil can move so epoxy helps there also. Normally epoxy encapsulation is done under a vacuum which draws the epoxy resin in between all the wires. This aids in cooling as well as wear due to wire movement.

Vacuum advance adds efficiency and part throttle power/driveability but as noted above does not add power at wide open throttle. I always try to tune my distributor advance mechanisms to use full manifold vacuum. Engines usually idle better and cooler.

Silicone heat sink compound, usually white, is different from silicone grease, usually almost clear. Silicone grease is a much less efficient heat transfer medium than heat sink compound.

 

Myth 9:They,re big!

The one I got off ebay worked fine,but I will not buy another one.Just because they are so big.To me it just looked goofy on a 302.

 

A lot of that size is to provide distance between the contact posts. With the high voltages developed with wider spark plug gaps the spark can arc over to the wrong post. If you notice all of the electronic ignitions have bigger caps and rotors than the points type ignition systems.

The larger units can look strange but they WORK!!! Which is all that counts. Functionality b4 beauty. The GM type HEI units do simplify the engine compartment wiring.

 

thanks for the info guys. i ordered one of the cheaper ones for now. its going on a stock motor. if i like it i will get a dui for my mud truck.

 

Good point!

 

I used a proform hei on the 393w in my 94 f150. (carb'ed and brain dead- no computer). It works good, but I had to grind the Edelbrock performer rpm manifold a little to get it to clear.

 

I just put one of the $60 Ebay HEI's on my 460 this weekend and I can tell you that it does work good but it is so big that I had to grind down my thermostat housing to make it fit. It does seem to work well but if you don't want a giant red distributor don't buy one.