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Built A HEI Distributor

On this page you will learn how to Built A HEI Distributor for the 1960-74 GMC Big
Block V6 Engines, using parts mostly form a 1979-78 Buick 231cld (3.8 L) even
fire V6 engine. Parts needed to start the HEI Distributor Modification. You need
a distributor from a 1978-79 Buick {Regal, Buick Park Avenue, Buick Skylark (rear
wheel drive), Buick Century, Pontiac Grand Prix, Grand Am, Le Mans, Firebird,
Oldsmobile Cutlas, & Oldsmobile 88}. These are just "some" of the GM cars that were
equipped with the 3.8L 231cid Buick V6 Even fire engine. You can find these at salvage
yards, eBay or you can buy them from a parts house. Below are the NAPA part numbers
& prices as of 20 Sept 2005. You will also need the drive gear from the GMC Big Block
V6 Distributor & a Custom Made Spacer/Sleeve.


Part Number




e-mail Rod Johnson

Custom Made Spacer/Sleeve



NAPA ~ 48-1694

1978 Buick 231ci V6 Distributor



NAPA ~ 48-1694

core charge



NAPA ~ RR203

Distributor Cap



NAPA ~ RR173





Igition Module



NAPA ~ RR204

Distributor Cap Ground Strap



NAPA ~ RR205

Distributor Cap Cover


Stock GMC V6 Distributor

Conversion #1 as done by Peter Chronis

To convert to a GM HEI here is what you need: First find an HEI unit from a 1978 or
newer up Even Fire Buick 231cid V6, make sure it's not from a computer command control
version that was used on many 1981 & up models. The shaft length is the same as the GMC's
but the gear is different, so you'll have to take off the gear & dowel pin from your GMC 305
or 351 V6 engine & transfer it to the Buick distributor shaft. When you remove the Buick gear
you will notice two squared off indentations opposite each other on the shaft, M.I.G. weld
these & have the shaft turned on a lathe till this area was perfectly round, if you're careful
& patient enough you may be able to do this with a file, you will be drilling this spot for
the dowel pin. Slide the GMC gear on, find the proper drill bit & drill a hole through. Next you
will notice the distributor hole on the GMC engine block is of larger diameter so it will be
necessary to have a steel collar machined to fit over the Buick distributor. Have a machine shop
make it up for you, measure the hole diameter in the GMC block & take both distributors to them.
The last thing is remove the ignition resistor wire & replace it with a solid 12 volt wire.
Some of you may think this is to much trouble to deal with. The results were well worth it, the
engine starts up with just barely turning the ignition switch, the engine pulls stronger at higher
rpm's, folks pulled 4000 rpm's with Holley 500 2bbl carb, 4.56 gears, 2 1/2 inch Flowmaster dual
exhaust. Last the biggest factors of going to HEI over aftermarket ignition was parts availability
& build up potential. When you're in the middle of nowhere & a module goes out it's easier to change
then a set of points, & just about everyone sells these including Gas stations that do repair work.

Conversion #2 as done by Edwin Erlbacher

Thinking of modifying a Buick distributor to fit into your GMC Big Block V6? The
preliminary drawings & photos done by Edwin Erlbacher may be available
by asking in our forum. Just take these to a machine shop
& have the parts made or modified as shown, then put them together & install.
NO Welding is requiered for this Method.

Custom Plug wires For the HEI Distributor

Custom Plug wires can be ordered from Magnecor Race Wires, you have to call & order
the set by the following numbers: One each of, C811, C814, C820, C826 & Two of the C822
to get a set of six. they run about $53.00 a set. Call Magnecor @ (248) 471-9505.
What do the number tell you about the wires? Example C822; "C" type, 8mm diameter, & 22"
long. I have included some photos of the custom plug wires installed on the engine.

Performance Upgrades For
Your GMC Big Block V6

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