distributor upgrade need insight

Hmmm, yeah. I'd think you'd want to measure how far the distributor sticks in compared to the old distributor. The up and down location of the two gears would affect the mesh. You may find the right approach is to shim between the block and the distributor rather than grinding the tip of the distributor shaft.

 

Yeah, very good point.
I made all of my measurements from the bottom of the flange face on the distributor.

 

The gears and shafts that I have done have been the same size shaft on the replacement hei as the oem distributor. One on a Ford 302 and one on a AMC 304. It is worth your time to check very closely to make sure the new piece lines up. The Ford gear was actually on the new hei upside down(thats when I started looking at the gears and decided that the original gear looked better then the new one did). After reading that people had problems with the Pro-Comp brand hei gears, I swapped the one I did on the AMC hei as well. The pieces are made to replace the oem part so they should interchange. These were in worn out motors to clean up 30 years of patches on original ignition systems.(paid less then $100 a piece for those pro-comp hei dists) If you have a new motor with a lot of money invested, you would be best to go with a system such as a DUI, or new oem components.

 

I have to go along with that... $400 is outrageous for a single fire factory style ignition since there are 'Factory' parts you don't have to worry about working with your engine MUCH cheaper...

First,
'75 had a Prestolite ignition in it.
No upgrades I'm aware of, and I do a BUNCH of this!

Switching over to the Jeep/Motorcraft distributor used from '78 to '90 isn't a big deal if you know how to set/switch distributors.

The Motorcraft distirbutor will give you a VERY STRONG trigger,
Good fly weight design, will be tuned for your engine, and will come with a shaft and gear that won't cause 'Issues' in your engine.

They run about $50 re-manufactured at places like Auto Zone and Advance Auto.
Pay the core, and when your swap is done, drop the old Prestolite in the box and get your core charge back.

Most of the time, I cut the wires for the old module off right at the module so I can reuse them with the new module.
(your Prestolite module won't work with the Motorcraft distributor,
And the Prestolite distirbutor won't work with any other kind of module)...

The Ignition Supply wire DOES NOT have a resistor in it, so you get a full 12 volts to the ignition coil and module.
I usually just put in a GM HEI style module (Discount Store) and use the 'Hot' wire to the old module on the new module.
Same with the coil 'Green' wire.

There is a diagram of your old system so you get the idea,



The coil 'Green' and the power wire from key switch both go to the module, might as well use them over! Makes things MUCH easier!



I WOULD take some 16 Ga. wire *Violet & Orange* and twist them together, around each other, and run a new set of wires to the pickup connector on the distributor!

Winding the wires keeps false triggers from happening,
And don't run them next to the alternator, spark plug or coil wires.

I get the modules from about a '79 Chevy Impala with V-8 engine.
They work fine and don't have 'Issues'.
Don't forget to mount the module on a 'Heat Sink' to take the heat out of the bottom plate of the module,
And use a real heat sink paste between heat sink and module.



I make my heat sinks out of everything from beer cans to computer processor heat sinks, even a solid plate of copper.
Just anything that doesn't rust easily and can be made flat.

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Switching over to the Ford style E-core coil is always a good idea.
(shown in the above diagram and on the LEFT in the image below),
V-8 engines require more discharges per engine RPM, so a faster saturating coil is a good idea if you ever intend on more than about 2,000 or 2,500 RPM!



I get them out of the salvage yards, they are everywhere, and Ford used an exceptionally high grade of ignition coil.
You also get the coil, wiring connector and bracket for about $5 instead of $50 for the coil and another $15 for the connector if you buy new.

Just find a late 80's or 90's fuel injected Ford vehicle,
Locate the coil wire, and follow it back to the ignition coil.

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This is important!

SPEND YOUR MONEY ON GOOD CAPS, ROTORS & PLUG WIRES!

The easiest way to do this is from Summit Racing.
MSD parts work GREAT, really none better on the market.

Use the DISTRIBUTOR CAP ADAPTER, BRASS TERMINAL DISTRIBUTOR CAP & ROTOR from a '79 Ford F-150 Pickup,
With 302 V-8 Engine.

This is the MSD version ready to install on the distributor.
Link: http://www.summitracing.com/parts/MSD-8414/



This is the best quality cap I have ever used.
The rotor and cap adapter are about what you would find in any parts store, but the cap is EXCELLENT compared to the 'Import' junk you get most places!

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Next come the plug wires!

DO NOT BUY CHEAP PLUG WIRES OR YOU ARE WASTING TIME AND MONEY.
Upgrading the distributor, coil, module does NO GOOD IF YOU CHOKE ON THE PLUG WIRES AND DISTRIBUTOR CAP!

Motorcraft (NOT Autolite) Plug wires are going to run about $45 or more, and they are probably the 'best' of the CHEAP wires.

MSD makes a WONDERFUL wire that comes with both sets of boots/connectors,
You cut them to fit so they actually FIT the engine,
They come with SNAP LOCK terminals,
Plug terminals can be bent from straight to 90 Degrees to facilitate install,
They come with stripping/crimping gauge/tool so you don't make mistakes,
And they have good instructions so you don't screw up...
Link: http://www.summitracing.com/parts/MSD-3119/



These are GREAT wires for what we do, price is reasonable, and they solve so many problems it isn't funny!

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DETAILS...

The distributor you get will probably be missing a cap adapter alignment tab...





This is VERY easy to make, you simply make it out of a tin can with tin snips or razor knife, needle nose pliers and a drill...

................

The SECOND detail is your connection to the distirbutor.

This little gadget keeps you from having to cut off your factory Motorcraft connector at the distributor...
Link: http://www.summitracing.com/parts/MSD-8869/



Nip off the little square plug at the end, and connect your 'Orange & Violet' wires to this with butt connectors (then heat shrink the connections!) and you can plug/unplug the distributor pickup if anything goes wrong with it instead of having to hack up the factory plug, then cut it back out of the wiring harness each time.

Just remember to fill the plug up with DIELECTRIC GREASE ("Tune Up Grease") so water/crud can't get into the connection and it works GREAT!

............

Detail 3,
Since you have MUCH more USABLE spark energy than before,
You should open your plug gap up to about 0.045"
Now that the spark energy is under control in the 'Large/Tall' cap and won't be jumping to ground or making cross fires anymore,
You can open up the plug gap and take advantage of the full 12 volt switching and coil feed!
No reason NOT to take advantage of the control you now have!

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REMEMBER!

This distributor comes with a 'Safe' gear and won't screw up your cam shaft gear.
This distributor comes 'Tuned' to your 304 engine and won't cause detonation, pre ignition, load problems or any of the other crap you get with many of the after market HEI Clone system.

You can walk into ANY Parts store and order a replacment module, cap, rotor, coil, distributor since it's ALL 'OFF THE SHELF' components, no waiting for proprietary this or that like you will with many systems.

An aluminum terminal cap might not be the best for your system,
But it WILL get you home on a Sunday afternoon when only the 'Tractor Supply' store is open!