Just wanted to give "Blue" some face time. Had carb rebuilt and spent Saturday dialing it and the timing in. Had problem with hard starting, but advancing the timing to 12.5 BTDC the car started right away. Thinking I was down easy street I took the car out for a drive only to find it began “knocking like crazy”. I started retarding the timing little by little beginning at 10d, 7.5d then to 5d BTDC. At 5d BTDC the engine initially ran without knocking, but became apparent at cruising trying to maintain 65mph. When the engine was shut off, it again was difficult to start - realized the engine didn’t like being retarded as much.
Began thinking some more about the situation and started thinking that since the engine was knocking under acceleration/load the vacuum advance came to mind. Thought about the Vacuum Advance Control Valve and went through the Service Manual on adjustments. The manual says it should pull 6 in. mercury but saw it was pulling 10 in. Tried to remove the VCA’s cover, but due to its location the cover was impossible to remove let alone adjust the spring. In order to access the cover the bracket holding it would need to be taken off, however it was secured by one of the intake manifold bolts. For obvious reasons I decided I didn't want to do that. It was late and getting dark so I called it a day and back to my think tank.
This weekend I think I'll just bypass the vacuum adv and run the distributor as as if it were a mechanical advance unit. I’ll just need to figure out the total advance curve and reset the timing accordingly. I’m pretty sure the knocking will stop if I do this. BTW, I do have Supreme (91 oct) in the tank.
Plugs, wires, cap, rotor, points, condesor replaced. This is a stock 383 2-barrel car, but carb upgraded to a 4-barrel Carter 3611S. Timing 12.5 BTDC, Points gapped at 0.17 and Dwell set at 30 degrees (28-32)
I have a Pertronix Igniter II and Flame Thrower Coil (40Kv) yet to install, but wanted to get to whole ignition system dialed in before I made any other change and end up chasing a new sympton.
Any ideas and/or suggestions welcomed.
Began thinking some more about the situation and started thinking that since the engine was knocking under acceleration/load the vacuum advance came to mind. Thought about the Vacuum Advance Control Valve and went through the Service Manual on adjustments. The manual says it should pull 6 in. mercury but saw it was pulling 10 in. Tried to remove the VCA’s cover, but due to its location the cover was impossible to remove let alone adjust the spring. In order to access the cover the bracket holding it would need to be taken off, however it was secured by one of the intake manifold bolts. For obvious reasons I decided I didn't want to do that. It was late and getting dark so I called it a day and back to my think tank.
This weekend I think I'll just bypass the vacuum adv and run the distributor as as if it were a mechanical advance unit. I’ll just need to figure out the total advance curve and reset the timing accordingly. I’m pretty sure the knocking will stop if I do this. BTW, I do have Supreme (91 oct) in the tank.
Plugs, wires, cap, rotor, points, condesor replaced. This is a stock 383 2-barrel car, but carb upgraded to a 4-barrel Carter 3611S. Timing 12.5 BTDC, Points gapped at 0.17 and Dwell set at 30 degrees (28-32)
I have a Pertronix Igniter II and Flame Thrower Coil (40Kv) yet to install, but wanted to get to whole ignition system dialed in before I made any other change and end up chasing a new sympton.
Any ideas and/or suggestions welcomed.
