Thank you!

 

Thank you. My timing light is adjustable.

 

Hi Everyone, hoping to rejuvenate this thread with a question. I timed the car initially to 14 degrees at idle with the vacuum line removed and plugged. The car ran reasonably ok but had a somewhat uneven idle, like it wanted to stall. When I reconnected the vacuum advance line the car ran much better and to my ear is now running well at idle and responds very quickly to blipping the gas. However, out of interest I reconnected my timing light and observe that with the vacuum advance line connected the car now shows around 30 degrees advanced at idle. Is that a normal characteristic? I'm hoping to take the car out this afternoon and don't want to be driving and doing harm if that condition is strange. Thanks in advance.

 

Yes, that's normal for a stock vacuum advance which is why MSD has the optional kit to change as well as the optional springs.

 

Thought I would share the info on using a vaccum limiter that came with my MSD dist. As you can see there is quite a bit of adjust available with a correctly working vaccum advance.

 

If you don't have a dial back timing light how do you find 36Deg if the harmonic balancer is not degreed?

 

You can't unless you apply a timing tape to the balancer. They aren't expensive, are commonly available (Summit, Jegs, etc), and work well as long as you align the TDC mark accurately.

 

I like To use ATI dampers that are marked 360°. SFi certified too. And rebuildable.

 

I see there are experienced members on this thread and I'm hoping to get some more help as a follow on to this thread. To provide context... A few weeks back the car engine cut out while it was idling in the driveway. Upon investigation I found that the coil in the HEI ignition was melted and I also found out it was a cheap, no-brand HEI distributor. I discovered that the spark plug leads were questionable and had extremely high and widely varying resistance, four of the spark plugs were threaded only finger tight, half the spark plugs were NGK non-resistor and the other half were Autolite resister plugs, and all the plugs looked heavily soiled. Lastly, I suspected that the12V supply to the distributor was questionable with too much voltage drop. To my mind plenty of possible reasons a coil would burn out. Realizing some sub-standard work had been performed I decided to replace everything to do with the ignition. New plugs (NGK R5671A - non resistor), new plug leads (Dragon Fire from Zip Corvette), MSD "ready to run" HEI distributor, and a fresh 12 AWG 12V supply. I used an MSD relay that closes when the ignition is on and supplies 12V straight from the battery. The car started right up and I set the timing on the new distributor using the advice in this thread. Took the car out this weekend and it ran incredibly well, more power and responsiveness than its ever had in the 4 months I've owned it. Then it suddenly cut out again at highway spped. No warning or missing just quit like the key had been turned off. I had the car towed home and started investigating. Firstly, I saw fuel squirting in the carb as expected so I don't think its fuel related. I figured it was the new relay that had failed or lost a ground but on checking found it to be working perfectly with a strong 12V supply to the distributor when the ignition is on. I then used an inline plug tester and saw that there is no spark. I tested the new distributor coil and the input and output winding resistances checked out fine. i checked the new plugs leads and as expected they were fine. Checked the distributor cap bushing and the rotor and see no issues, so at this point I'm pretty sure the ignition module has failed, but the question is why? Two fried distributors one after another seems too much coincidence. And then something really strange happened. I turned the ignition off (it had been on while I was checking and tracing voltages through the distributor wiring) and the car moved slightly. Nope, I hadn't been sampling the green stuff, the car moved slightly. So, thinking about this the only way that could happen is for the starter motor to be in play. There was absolutely no sound or clicking from the starter motor but something turned the engine very slightly. I have a crazy theory as yet unverified: the cog on the starter motor is permanently engaged with the flywheel (its a mini, high torque starter) and there is a partial voltage leak in the solenoid with the ignition on that is enough power for the starter motor to exert pressure on the flywheel but not enough to turn the engine over. When I turned the ignition off it cut the power which caused the cog to stop trying resulting in the flywheel moving back slightly. Coming back to the two fried ignitions, its conceivable that a partially shorted solenoid or even the effect of the starter being spun by the engine continuously could cause spikes that could harm the ignition components. Is this theory remotely possible? What else could cause consecutive ignition failures and the symptoms I'm seeing? How do I even begin diagnosing what might actually be going on? Thanks in advance for any ideas!

 

Have you measured the voltage to the distributor,?

 

Wondering why a relay is needed for power to distributor. Why not running power from fuse block or wiring harness behind fuse block?

 

You can do that and many do. The relay approach allows for the shortest possible run from the battery to the distributor and the lowest cable resistance. There is often a small power drop on the ignition circuit. I use the 12V from the fuse panel to trigger the relay instead of powering the distributor directly. MSD recommends use of the relay but it isn't essential.

 

12.6 volts at the BATT terminal with the ignition on.