Engine is 93 Volvo 570 MS4, Prestolite BID distributor (mechanical advance). It's had new plugs, wires, carb rebuilt, new OEM coil.
I was timing according to Volvo Service Manual spec, 6 BTDC (idle), 23 BTDC @3000RPM (stroboscopic, yes it says stoboscopic). I used a shop tach, idle set at 800 RPM. Balancer has a timing tape which appears to have been correctly installed. I used a basic timing strobe light, not the advance kind.
I set idle at 6 BTDC, observed timing mark while increasing toward 3000RPM. The timing mark advanced past 23 BTDC before I got close to 3000 RPM. Probably even past 29 BTDC (6+23) but I stopped messing with it til I "geet understanding" so I don't know where it would have stopped advancing had I run it up to 3000.
Here come the questions...
1. Exactly what BTDC degree should I see on the timing tape at 0 notch on the timing tab with a basic strobe light and engine turning 3000 RPM?
2. Some talk about adding initial+total to get final timing but, the Volvo manual says "stroboscopic", which seems to mean that's what you ought to see with the timing light. I've read that 30 degree range is normal for SBC total timing. Is Volvo assuming use of an advance light?
3. After setting final (stroboscopic?) timing right (per answer to step 1), I'm guessing idle timing will be ATDC and the engine will idle poorly. How to fix? Adjust idle up, maybe readjust idle mixture?
4. Why doesn't the stock advance mechanism keep timing within the proper range. The advance mechanism seems corrosion free, and intact, no broken springs. Will replacing springs, maybe weights in the advance mechanism help?
5. Does the distributor have to be removed and disassembled to replace weights and springs?
I was timing according to Volvo Service Manual spec, 6 BTDC (idle), 23 BTDC @3000RPM (stroboscopic, yes it says stoboscopic). I used a shop tach, idle set at 800 RPM. Balancer has a timing tape which appears to have been correctly installed. I used a basic timing strobe light, not the advance kind.
I set idle at 6 BTDC, observed timing mark while increasing toward 3000RPM. The timing mark advanced past 23 BTDC before I got close to 3000 RPM. Probably even past 29 BTDC (6+23) but I stopped messing with it til I "geet understanding" so I don't know where it would have stopped advancing had I run it up to 3000.
Here come the questions...
1. Exactly what BTDC degree should I see on the timing tape at 0 notch on the timing tab with a basic strobe light and engine turning 3000 RPM?
2. Some talk about adding initial+total to get final timing but, the Volvo manual says "stroboscopic", which seems to mean that's what you ought to see with the timing light. I've read that 30 degree range is normal for SBC total timing. Is Volvo assuming use of an advance light?
3. After setting final (stroboscopic?) timing right (per answer to step 1), I'm guessing idle timing will be ATDC and the engine will idle poorly. How to fix? Adjust idle up, maybe readjust idle mixture?
4. Why doesn't the stock advance mechanism keep timing within the proper range. The advance mechanism seems corrosion free, and intact, no broken springs. Will replacing springs, maybe weights in the advance mechanism help?
5. Does the distributor have to be removed and disassembled to replace weights and springs?