Hei conversion troubleshooting
I am about ready to tear my hair out. Problem is not fixed. After my wiring job was done Last night, I took an old crappy distributor cap with corroded contacts and drilled a big hole in the side to check rotor phasing. Fired up the car and thats when I thought it was fixed, clean revs throughout the range.
This morning, I swapped the new dist cap back on (brass contacts) and the car ran like **** again. Back to the original problem. So then I suspected it was an issue with the cap. How a cap with corroded aluminum terminals is working better than a new cap with brass terminals, I don't know. But when I swapped the old cap back on it still ran like ****. And the voltage is back up to 16v at idle. I think the huge voltage draw/overcharge is related to the poor running condition. Whatever is causing this misfire and poor running condition is also drawing a huge load from the charging system. Probably the HEI trying as hard as possible to fire. When the car randomly decides to run right, the voltage drops down to 14 at idle. The conditions are definately linked.
As best as I can tell with side by side comparison, the caps are the same orientation, dimensions, relation of terminal locations, etc. So I think it was just a coincidence with the cap swaps.
Rotor phasing *appears* to be perfect. At idle with vac advance plugged, It is firing on the leading edge of the contact. It stays steadily in that spot as the car is revved up. With vacuum in, the rotor moves closer to center/trail edge of the contact.
Either way, the firing is erratic. Now I am noticing I can't actually idle as low as it should, and that the spark is intermittent at idle also.
Also make sure the ground is good clear to the battery. I use a no 4 "starter" cable (eyelet to eyelet) about a foot or so, shortest you can buy. On a smallblock there are unused holes on the rear of the driver side head. Bolt the cable to one of them, out of the way. Bolt the other end either to a through bolt and nut through the firewall, or use one of the master cylinder mount studs.
I'm going to install some new grounds today from batt cable to sheetmetal. See what that does. But it does appear that the charging system is working properly and just overcompensating for the massive draw this misfire is causing.
