Thread: Engine wont start. Could use some help and ideas.

Tweet

First, replace the vacuum line from the manifold to the modulator. That's normally where the problem is, the line has chafed against some part of the car and over a period of time has worn a hole in the line. Take vacuum off the manifold. There's usually at least one threaded plug hole you can use.

Secondly, the 14 inches of mercury manifold vacuum tells me that you have cammed the motor. When you do that, the motor needs more initial ignition timing at the crank. I think you said you have L31 heads on the motor. The combustion chamber of those heads likes 34 degrees total (initial and centrifugal) ignition timing. The cam, depending on cam timing, will want from 14 degrees to totally locked out at the crank. If it were mine, I'd dial in 16 at the crank and modify the centrifugal for 18 degrees, for a total of 34 degrees, all in by 2800 rpm's. If the motor wants to kick back against the starter with this much lead, interrupt the hot wire to the coil and run a wire to the drivers compartment to feed a switch, then back to the coil. I like a normally-closed push-button switch, but any good-quality 15 amp switch will work fine. Mount the switch so that you can operate it with your left hand. Cut the power with your left hand while you operate the key switch to start the motor. The motor will wind up pretty good with no fire to the plugs. Once she's wound up, let go of both switches and the motor will be idling. With this modification, the starter will likely outlast the vehicle. With more initial lead at the crank, the motor will be more responsive, particularly to the air/fuel screws at the venturis and you'll likely see more manifold vacuum.

Finally, replace the vacuum advance cannister with a Echlin #VC-1810 advance can, also known as GM PN 88924985 and AC-Delco #D1312C (aka "B28")
__________________

.