Points distributor, I'm assuming, since you said stock '69 and setting the dwell?? Are the contact faces clean....they will scuzz over when they sit unused for long periods

How old is the fuel??

What brand/type sparkplug sires, and how old are they(mileage-wise)??

 

I ran an ignition file over them to clean up the surface. The fuel is new, as is the entire fuel system. The spark plug wires are restoration pieces from one of the vendors and they're brand new with only the dyno run from three years ago on them. I forgot to mention I also replaced the battery while trying to figure out what was going on and it didn't help either.

Another thing: I've been checking the voltage at the + terminal of the coil and noticed that the voltage with the key in the run position was down at about 4V when it is supposed to be 9V. In case the reduced voltage was causing a problem I ran a temporary line with 12V to the + side of the terminal. I have my hand held starter switch to assist in the ease of diagnosing things so I had the key in the run position for a four or five minutes while I checked a few things, which put the 12V into the coil, a new MSD blaster 2 coil. When I touched the coil it was boiling hot! It made me so concerned I disconnected the battery to make certain it wasn't getting any more power and could cool down. The wire I ran to the coil was fuse protected and the fuse didn't blow so this isn't from a short this is just from getting standard 12V power. Is that supposed to happen?

 

With the key on, engine not running and the points in a closed position it will continue to charge the coil primary windings....coil fires when the 8 lobe point cam on the distributor shaft pushes the points open....the instant the points open breaking contact to ground, the magnetic field in the coil primary collapses and the spark is fired from the secondary side.

It will get hot from key on, engine not running if points are closed at that time.

 

Thanks Eric. Any thoughts on the original problem? This is a restoration I'm doing on this 69 corvette. This car has a resistor wire to the + side of the coil and runs 9V there to help increase longevity of the points. At the start of this, the coil was getting the 9V to the coil with the key on, but now it's only getting 3.8V. I'm not sure what I could have done to knock the voltage down. I have been cranking the car with my battery charger in place, but only on the 40amp rapid charge setting, not the car start setting. I can't see how that could burn out the coil wire. And the battery is fully charged and brand new so it shouldn't be the battery. I'm at a loss to explain why this car won't run.

 

Are you certain that you don't have a huge vacuum leak?

 

Sparkplugs could be glazed.
No cure for that except new ones.

 

Probe the resister ignition wire where it comes out of the firewall plug, see what voltage is there. If low there, go inside to the fuse panel and start checking it there. Could be bad connection between the two halves of the old fuse block.

 

Ok. I’ll try and chase down the resistor wire and see where the voltage drop is.

It def could be a vacuum leak. These 69 Vette’s have a huge vacuum system, it runs many of the functions on the car. I thought they were all connected but it could still be leaking. I’ll disconnect and plug the line at the manifold and see if that helps.

 

If that doesn’t work my next step is to replace the distributor and add an MSD box. It would only be temporary for diagnostic purposes since this is a frame off restoration. It just seems like there isn’t enough power to fire the spark plugs. This is very weird. It really has me stumped.

 

Have you run a compression test since trying to wake this thing up ?

 

You need some good grounds. Grind down to bare metal on the motor somewhere and the frame somewhere and run new braided ground wires back to the negative terminal on the battery.

 

I have not run a compression test since it was on the dyno.

It has several ground wires already. The factory setup for 69 corvette includes multiple ground wires between the motor and the frame, which is where the battery is grounded. I’m pretty sure It’s adequately grounded, but if I fix the other problems and it doesn’t solve it I’ll look into another ground wire.

I put in new plugs after struggling to get it running initially but that hasn’t helped. When I pulled the plugs they were black and reeked of gas. Since it has a new carb it really makes me think this problem is related to a problem with spark. It might take replacing the distributor to get this thing running. Once I get it running I can work back to the factory set up but I can’t tune it if it doesn’t run.

 

Before throwing money at msd, do you know or can you find someone with dist machine? would be nice to test, prove and set up the dist on machine, at least you would have a known good or bad item.

 

Is the "new" carb 3 years old like the engine overhaul ? Have you taken the top off & looked for debris , cleaned the needle & seat , checked the fuel pressure ?? If the plugs came out fouled , there's a good chance the carb is bleeding , maybe one of the above ?

 

I wouldn't waste the money on the MSD ignition box and distributor. If you want to keep it original , implying points, then do so. If you want to convert it to something else, then put a budget oriented HEI distributor on it.

You're at the spot presently that a spare HEI (coil in cap) distributor would be great to throw in and see if it starts. You wire the 12 volt dizzy wire to a relay or high amp rated switch directly to the battery (fused of course) to eliminate your resistor, points, coil, wiring as an issue. If it doesn't run when proper spark is applied, then you know those parts aren't the issue.

Regarding your current parts, how does the cap and rotor look inside of the cap? Corrosion build up on either will cause exactly what you have going on. Where are you located? If near to me, then you can borrow my HEI coil in cap distributor. I also have a small cap with an external cap that is in standby mode at all times.

And x2 with TI on a crappy ground causing the issue. You mentioned you have two grounds - that's not enough. You should have the frame to the chassis, frame to engine, chassis to engine, and then of course the engine to battery. Several chassis to frame grounds is not a bad thing. And you can check your grounding with either a Power Probe or multimeter.

Good luck - Jim

 

I'd get the IGN switch / resistance wire / coil voltage issue sorted out before I dropped any money on a new distributor. Voltage at coil "+" terminal should be around 9 volts with engine running, like you initially saw. However that's with the engine running, so it's sort of an average of points being open/closed.

Also, I'd make sure voltage at the the coil "+" terminal is the same using various grounds for the meter's ground lead. In other words, make sure all grounds are at the same potential with current flowing.

On a somewhat related note, do you know that in the IGN switch's START position the "R" terminal on pre-HEI GM starters puts full battery voltage on the coil "+" terminal to aid with starting? Then once the IGN switch springs back to ON, all current goes through the resistance wire. The absence of this connection won't affect running, but it can make starting difficult. if you have a new starter without the "R" terminal, you can wire a relay to accomplish the same thing.

Finally, I second what someone said above about taking the carb apart for inspection.

 

Carb is brand new out of the box this week. One of the first things I swapped out. I have also just plugged the vacuum port in the manifold to eliminate a vacuum leak as the problem. It had no effect.

It turns out that the voltage at the coil was 3.8 In the ON position with the new MSD blaster 2 coil I was using. When I swapped it out for the original coil it was back to 7V so the coil wire voltage issue is solved, although I’m not sure why the MSD coil would have a lower voltage. Perhaps I killed it when I left the key on for a few minutes and it heated up? In any case swapping the coil had no effect. I know the R wire provides 12V at ignition. It is in place and I get 12V to the coil when cranking.

Cap and rotor are good, no corrosion at all and they only have the dyno run on them.

Jim I see your in Binghamton NY. I’m in San Antonio TX. Appreciate the offer. I’ll ask around locally and see if someone has something I can borrow before buying a new distributor.

This is a corvette so the battery grounds to the frame by the rear end where it sits. There’s no practical way to ground the battery directly to the engine. There are four factory ground cables that connect the engine to the frame. This has proven adequate on literally a million+ corvettes (it’s not a TI ignition). I’m pretty sure it’s not a Ground cable issue but at this point I’m not opposed to trying anything. I will add another battery cable gauge ground between the engine and the frame.

 

Carb is brand new out of the box this week.

Uh... oh... What brand of carb.? If it's an Eddy, the stock fuel pump will flood it over!

The voltage at the coil will vary depending on whether the points are open or closed at the moment of testing... if the coil got too hot, it may have fried...

A Crane/F.A.S.T. electronic ignition keeps the distributor stock...
https://www.summitracing.com/parts/fst-750-1715

As Eric mentioned, after 3 years you'll need fresh gas in the carb, fuel filter, lines, and tank... probably need premium pump gas plus some kerosene or other octane booster for that 11:1 engine...

 

Isn't there a positive cable going to the engine , any reason you can't run a negative cable the same way ? FWIW just because the carb is new doesn't make it good ...

 

It’s a Holley carb. I scrapped the MSD coil and went back to the stock one.

I’ll look into that ignition upgrade. Beats popping for a new dizzy.

The fuel system, from tank to carb is new and has never seen fuel. I used the stock Quadrajet for the dyno run but switched to the new Holley when it wouldn’t start. Of course the new carb could still be bad but I’m using the old saying, “if you hear hoof beats is usually a horse, occasionally a zebra, and almost never a unicorn.” It’s pretty unlikely that the new carb would be bad enough to keep the car from running. It could definitely be out of tune for this engine, need to be rejetted, etc., but unlikely to be bad enough to not run. The fact it still doesn’t run tells me more about the original carb than the new one. It tells me the original carb is likely to be fine and that the problem is somewhere else.

 

Yes, don't throw money at it... figure out what is really wrong...

After filing points, close them on a clean business card, rotate the card around a bit to clean off residue and then pull it out... recheck the gap... blow some air on them...

 

I was going to recommend a Pertronix unit similar to what Buzz recommended. I put one of on a points dizzy to run an external coil - worked great and eliminated the need for any of the resistance wire and adjusting points.

I have to say though, you're at a point here of a fresh start. A quick compression check on the cylinders that are easy to get to (4 cylinders with good compression and it will at least run), then a manual fuel pressure gauge at the carb, and then checking spark the old fashioned way - lug attached to the wire out of the cylinder. If all 3 of those are good, then .....??? But I'll say that one of those is not OK. Hookup a vacuum gauge as well to see what it does when it spits and sputters.

 

OK so I pulled and cleaned all the plugs and they didn't look too terrible. I also tested each wire with a spark detector and they appeared to all be getting spark, although I'm unclear about the quality of the spark. Then I tried starting it and was cranking on it off an on for a few minutes. The total time cranking it might have been 45-60 seconds. I did not leave the key on if I wasn't cranking it. I then went to check something on the engine and noticed the coil was boiling hot, just like what happened to the last coil. Is that expected if your cranking the engine for a minute or two? That seems like it shouldn't be happening. I mean, if it got any hotter it would be a fire hazard I would think. If that's not supposed to be happening, what could be causing it to overheat like that? Also, I was so concerned I decided to disconnect the + coil wire just to be certain it wouldn't heat any more and burst into flames. The key was not even in the ignition and there was an arc when I pulled the wire. I got my voltmeter and the coil wire had 12V with the key out. What's going on??? Do I need to call a priest and have an exorcism for this thing???

 

I'd take a voltage reading with the key off and see if you're still getting voltage at the coil!

 

I was getting voltage with the key off but I figured it out. My remote starter switch clamp that was on the + starter lug slipped and was making contact with the R lead. When I separated them the voltage went to zero.

 

Did it start and run then?

 

I installed a Pertronix in the stock dist. years ago and it's still trouble free.

Could the dist. be 180 degrees out. That's common with Chevy's along with switching 5 &7 plug wires.

If you're using the Vett plug wire channels, try the wires o/s the chrome hat and channels

Good luck