Hot rodding the HEI distributor
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(→Electrical connections: Add images, text; minor clean up) |
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The large diameter of the cap helps to prevent this and it works well enough in a passenger car, even with the wider gaps that were used for some applications. But once the RPM goes up and the cylinder pressure increases, the chance of a misfire increases dramatically with a wider plug gap. | The large diameter of the cap helps to prevent this and it works well enough in a passenger car, even with the wider gaps that were used for some applications. But once the RPM goes up and the cylinder pressure increases, the chance of a misfire increases dramatically with a wider plug gap. | ||
| − | == | + | ==Wiring an HEI distributor== |
| − | [[File:Hei coil cover wire diagram.jpg|thumb|350px| | + | [[File:350px-Hei coil cover wire diagram.jpg|thumb|350px|right|HEI coil cover]] |
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The HEI ignition requires a switched 12V DC power supply (without any resistance from a ballast resistor or a resistor wire like was used on many GM points-type ignition systems), and a ground. The coil cover has the wiring positions marked on it: | The HEI ignition requires a switched 12V DC power supply (without any resistance from a ballast resistor or a resistor wire like was used on many GM points-type ignition systems), and a ground. The coil cover has the wiring positions marked on it: | ||
*Left is the tach terminal | *Left is the tach terminal | ||
| − | + | *Right is the 12V switched power source (circled) | |
| − | *Right is the 12V switched power source | + | *the pigtail from the distributor is attached to the three terminals closest to the coil (arrow). |
| + | *The HEI ground is through the distributor body to the engine, then to the battery negative cable. Be sure there's no paint or grease, etc. insulating the hold down clamp and bolt from grounding the distributor to the engine. | ||
<br style="clear:both"/> | <br style="clear:both"/> | ||
| + | If converting to an HEI from a points-type distributor, the wire that was used to supply current to the point-type coil will be a resistor wire. This is not needed or wanted for the HEI- it needs to be supplied with full system voltage without any resistor wire or ballast in the circuit for best performance. Depending on the application this could mean rewiring or replacing the resistor wire for a 12-14 gauge supply wire. Also, the wire from the starter solenoid “R” terminal can be eliminated. | ||
| − | + | New replacement HEI power and tach hook-up pigtails are available. These pigtails are a better solution than using a crimp-on type female spade connector because the pigtail has a much more robust design that won’t break off even after repeated removals. They also have positive retention clips that prevent the connection from falling off. | |
| − | + | Another neat wiring aid is the Accel p/n 170072. It’s a combination HEI battery/tach pigtail that has a connector for both power to the HEI '''''and''''' the connection for the tach, molded together. A tach wire connector isn’t needed if using an MSD box that has a separate tach hook-up; in that case use just a stock-type HEI power supply pigtail. | |
| + | {| | ||
| + | |[[File:Painless 30809 hei power.jpg|thumb|center|200px|Painless p/n 30809 stock-type power wire]] | ||
| + | |[[File:Hei tach pigtail.jpg|thumb|center|220px|Pico p/n 5664PT tach wire]] | ||
| + | |[[File:Accel 170072.jpg|thumb|center|315px|Accel p/n 170072 combo connector for power and tach]] | ||
| + | |} | ||
| − | + | ===Ignition interrupter=== | |
| + | There are times where the engine requires so much initial timing that the engine can be hard to start without kicking back against the starter. If this is encountered, a simple momentary off switch can be wired into the wire that supplies battery current/voltage to the HEI. In a stock application this wire is often pink and a relatively large gauge. | ||
| + | |||
| + | Put the switch in series with the power wire and route the wires inside the vehicle so the switch is within easy reach of the driver. | ||
| + | |||
| + | To use the interrupter, the switch is depressed (or toggled, depending on the design) and the engine is cranked via the key/starter switch. Once the engine is turning over, the switch is released. This powers up the ignition and the engine will start without kickback. | ||
| + | |||
| + | ====Starter brace==== | ||
{| | {| | ||
| − | |[[File: | + | |[[File:Sbc starter brace.jpg|thumb|330px|left|SBC starter brace]] |
| − | |[[File: | + | |[[File:Starter brace install.jpg|thumb|330px|left|Brace attaches to studded through bolt on starter and is bolted to the block]] |
| − | + | ||
|} | |} | ||
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| + | In addition to the interrupter switch, a starter brace should be used to help prevent broken starter noses or damage to the mounting ear of the block. On the SBC and BBC, a brace like was originally used by the factory is still available to prevent the starter from flexing in use. | ||
| + | |||
| + | The brace connects to the end of the starter opposite of the nose, using the studded through bolt to attach the slotted end of the brace to the starter. The other end of the brace attaches directly to a threaded boss on the engine block, just below where the block deck and head meet. | ||
==Parts of the HEI system== | ==Parts of the HEI system== | ||
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