Thread: General Hemi info part 4

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If you are doing a 331/354 or 392 HEMI you do have some aftermarket alternatives available to include magnetos, converted Chevy units, and even billet units. If your running the Dodge or Desoto’s you also have some options (check the Hot Heads web site).

Chrysler made distributors real confusing for the Early HEMIs. Although they all used the same cast iron housing, the shaft lengths were different even within the same Division. Chrysler is a good example, the 331-354 Dist have the same shaft length but the 392 uses a longer shaft due to the raised block design. The length of the Chrysler distributor shafts is different than the Dodge and Desoto and also different than the latter 318 Poly/LA and the B and RB engines.

If you happen to have the correct distributor for your early HEMI and don’t want to mess with the points, a lot of people seem to have good luck with the Pertronix conversion.

My solution to get electronic ignition was to convert the original distributor to electronic using Chrysler parts. All the upper parts from a Mid 70’s MOPAR SB will fit the cast iron housing (to include vacuum advance). You must use the SB parts and not the BB as the distributors rotate in different direction and the advance will not work with the BB pieces. Simply replace the breaker plate and point cam with the electronic ignition breaker plate, pick-up and reluctor (you can find the how to in almost any 70’s shop manual). If I remember correctly you may have to drill or enlarge one hole for the breaker plate attaching screw. This set up uses the latter style rotor and early cast iron distributor cap (original style HEMI cap).

If you happen to have a hard time finding the original style cap, you are in luck. It is the same cap used on Mallory’s dual point and unilite distributors.

Finally, the early HEMIs used a long insulator on the spark plugs. These are usually missing or broken. You are not necessarily stuck buying a new set of HEMI spark plug wires with the insulators or checking E Bay to get these parts. Nor do you HAVE to buy a set of 426 sparkplug-well boots if you are not running the original wire covers. Many of the foreign 4 and 6 Cyl cars were a hemi head design and used the long insulators and boots. You can usually find these at a salvage yard for next to nothing. Buy a set of universal plug wires so you can cut them to the correct length, thread the new wire through the boots and insulators, crimp on the sparkplug terminal and pull back into the insulator, instant cheap HEMI wire set.

Shown below are from top to bottom; my cheapie set of HEMI plug wires, 331/354 HEMI distributor converted to electronic ignition (also the HEMI cap and late rotor) and some OE ceramic insulators