Getting good spark and a precise tune is step one for making any engine run better, but doing it with worn-out parts isn't going to get you there. Upgrading all the external components like coil, wires, and plugs is a start, but to keep your engine firing precisely, the internals of the distributor need to be in tip-top shape as well.
Replacement aftermarket distributors run the price gamut from the ultra cheap with questionable quality, to high end and pricey for guys making big power. But if you're on a budget, there is another option-you can keep your vintage HEI, and just upgrade the internals with affordable and effective mods to make it hot rod ready.
Our HEI unit was yanked from...
Our HEI unit was yanked from the tired 350 in our '68 Nova project. If you don't happen to have one lying around, used units are readily available at online and at real-life swap meets for around $20 to $40.
Usually considered the father of all modern ignition systems, GM's venerable HEI ignition made its initial appearance in a few '74 models, but became standard equipment by the following year. One of the main breakthroughs that put HEI miles ahead of previous points-style systems was its then-revolutionary expanding dwell circuit, which increased the amount of saturation time experienced by the secondary side of the coil as rpm increased. That concept brought in more power where it was needed most; under high rpm and load. Plus, without troublesome points to wear, the current carrying capacity, voltage, and spark duration all went up while the required coil charge time decreased. That's why to this day, HEI remains a staple for any hot street/strip engine that makes all its beans under 6,500 rpm.
Here's our exploded HEI next...
Here's our exploded HEI next to the Summit Racing and Pro Comp replacement parts we plan to use. There's no real science to disassembly, just a few screws and everything comes apart. This much disassembly isn't necessary unless you plan to replace the shaft bushings.
Nowadays, the ignition evolution continues with strong aftermarket support that has made rebuilding and upgrading HEIs a quick and easy project that just about any rodder can bang out in a couple hours or less-even if you're a perfectionist who takes the time to detail the housing.
|WHERE THE MONEY WENT
|PC1031D cap/rotor and coil
|PC6045 vacuum advance delete
|PC6043 wiring harness
|Summit Racing HEI advance curve kit
|High-output four-pin HEI performance module