do not believe there will be enough room for an HEI large cap (coil and distributor in one) to fit. 

The external coil and small cap factory HEI was used on a many pick-up trucks and early Camaro's. Be carefully of the year of the donor vehicle; as an external cap HEI off of an OBD computer controlled car won't work (you can count the pins on the ignition module to determine if it will work. Four pins is what you want; five or more won't fly).

MSD, Accel as well as Mallory all make a small cap HEI unit that is better than the factory product because of improvements to the distributor body (using roller bearings instead of brass sleeves, and a billet body instead of a cast unit). The major difference is found in the ignition module itself. The aftermarket unit uses different components that shed heat faster than the stock unit can to maintain a steady spark above 4,500 RPM where a stock HEI drops off in spark energy (the stock factory coils refresh rate also enters into this, which is why the aftermarket sells coils matched to their ignition modules). 

Finally if you want it to look stock you can rework your old distributor by replacing the points with a self contained Petronix HEI ignition module and slip a reluctor ring over the distributor cam. There are people on the web who advertise this rebuild as a service (worth considering if your distributor needs to be rebuilt to compensate for years of wear).

Mike Ward MB wrote:

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There were also the "make room with a big hammer" suggestions.

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 That's a popular suggestion by some.

Could always go with 1 of these if stock won't fit, put 1 in my 57 and swear I gained 15 HP.

Carl Stevenson wrote:

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Gaining 15 horsepower wouldn't make me swear!!!

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 You swear your telling the truth?

Whitey67 wrote:

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Hello:

Has anyone installed a stock HEI with a  standard cap to a 66/67 Acadian with a small block?

Just wondering if the standard cap will fit without altering the firewall.

 

Thanks

 

Dave.

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