The summer has progressed with the same cadence as the rest of the build: major steps forward leading to equally large steps backward . . .
The idle was ultimately sorted out a few weeks ago – but not until getting sidelined by vapor lock and then totally stranded on a road test by NOS ignition parts.
I had read numerous pieces warning not rely on ‘shelf worn’ ignition bits: “they age even without use – so they are no longer 'ehm' new” . . . but the car seemed to run quite well on my vintage ‘Extra Super’ BAP (Bosch) coil – right up until it quit. Replaced that with a new NAPA Echlin unit and now it runs better then ever . . .
With the engine warmed up I disconnected the linkage completely and removed the interconnect rod from the Heim joints. Then I started the car and proceeded to balance the idle between the two carbs using the Uni Syn tool. Then I reconnected the linkage and went to work on the cold fast idle. The rear carb has the fast idle screw backed all the way off. The front carb is two full turns backed off from where it came out of the box. With the firm linkage between the two units when the front carb is on the fast idle cam the engine turns north of 1200 RPM. I think I can lower this but will wait until some late fall cold weather testing to prove this out.
Once the engine is warmed up the auto-chokes and fast idle linkage go limp . . . allowing me to further dial things back to a quiet ~ 750 RPM:
216 Idling @750RPM quiet if one ignores the characteristic solid lifter chatter!!
I used the vacuum method the set initial timing. Max vacuum called for a little over 15 degree BTDC of initial timing @ 21”. This proved troublesome for hot starting and exhibited a rough idle when attempting to throttle down toward 1000. Testing has resulted in backing off initial advance to just 8 degrees BTDC @ 18’’ of vacuum.
