Usually starts immediately, but not today. At first it turned over....and over....and over. No start. Gas...OK, plenty out the carb. Spark.....I'll have to troubleshoot. It made a slight popping noise, and discharged the battery on the last try. I recharged the battery, tried again......slight pop, then dead, not even lights. Turned key again, lights came on, but died when starter tried (clicking noise). Sounds electrical, like something's shorting out.........battery and coil OK (HEI)......fusible link?

 

Fusible link by starter and check all your grounds.

 

I had a similar starting issue when I purchased my 73.
My battery to frame ground cable was corroded under the insulation to the point that it was intermittently making the ground connection.
The cable looked like it was in good condition until I disconnected it from the battery and noticed a slight bit of green at the end of the connection.
When I pealed back the insulation, I found there was only a couple of good strands of copper left.
I replaced the cable and my starting issue was corrected.
Hope that helps.

 

Looks like my work's cut out for me this weekend. I'll start with that negative battery cable (probably should be replaced anyway, it's 53 years old). Can the fusible link by the starter be jumpered around for a test to start the car? Can the link be easily replaced, or does the harness have to be replaced with it?

 

Fusible link can be replaced fairly easily. New harness would be nice but they are not cheap for a good one.

 

Well, weekend is here, so decided to tackle the "no start" problem again. Neg. batt cable.....great condition. This new motor hasn't been in the car that long, with about 1500 miles. on it. And all the wires were inspected and taped where needed at that time. So, double checked the fusible links at the starter and horn relay......they looked almost new (to my surprise), so I decided to move on before cutting into good looking wires, maybe coming back later if necessary. Jiggled every thing, nothing appeared loose or burnt. Checked battery voltage...still 12.8 volts, nothing was draining it. I turned the key......nothing..... completely dead. I decided to recheck battery voltage. When I touched the pos. battery terminal, lights and everything came back on. I removed the pos. terminal and found corrosion, enough to stop connection. I cleaned the wire and installed a new battery terminal. Turned the key, everything's back on, strong turnover, but still no start. Oh, well......I'll check for voltage to the distributor, and I have a spare module and coil to try just to eliminate those posibilities.......

 

On my 1968 C3 you simply check your Horn relay to see if it has 12Vdc going to it. If not, the fusible link is burned. I had it happen once when a Component wired to the fuse block decided to "let the smoke out". On my 1968 both fusible links are very close to the horn relay and very easy to check. IF you make holes in the wire's insulation jacket be SURE to seal them up after testing. Those little holes in the insulation can cause the wire to corrode inside and cause you more grief later on down the road.

 

Well, after double checking wires and battery cables, I looked toward the distributor......changed module, coil, rotor and cap. No change, still no start. Heck, I even tried a spare distributor that I know is good in case it might be a bad pickup......no change. After several attempts to start, It sputtered a couple times, coughed a couple times with some "boof" sounds (uh oh) coming from the motor. Double checked TDC and firing order.....everything fine. I even sprayed in some starting fluid (which usually starts anything)......no change. Just a cough, and a harsh sound coming from the engine if it does try to start. I'm frustrated......this is beyond my DIY mechanical knowedge.

 

So, back to the basics!
Pull a plug wire and see if you are getting spark at the plugs.
What voltage are you getting at the coil?
What is the voltage at the coil while cranking the starter?
Are you using the resistance (pink) wire to supply 12vdc to the coil?
If so, you are probably only getting 10.5vdc +- during cranking, which will not be enough voltage to supply a proper spark to the plugs and the engine will not start.
If you’re using the pink wire, run a new ignition wire from a good 12vdc source at the fuse box directly to the coil so you have proper voltage at the coil.
The original resistance wire was designed to reduce the voltage during engine cranking to protect the points.
HEI or any other electronic ignitions require a full 12 vdc to operate.

How was it running the last time you drove it?
Have you tried swapping out the battery with a known good one or had yours tested?
Keep us posted!

 

Are you getting fuel to the carb?

 

Fire, Fuel and Compression is all that's required to make an engine run. Safe to assume you have fuel and compression so look for fire. You said you swapped out the dist so I'm assuming you did a TDC check to rule out timing issues.

 

So......................Plenty of fuel to the carb (ProSystems 1040 CFM)
New battery, Odyssey 850 cranking amps.
Car was running OK when put away last winter, but has not started when attempted this year.
DUI HEI distributor, new tune up parts (rotor, cap, etc.)
Distributor is powered by a dedicated +12v wire from the fusebox ignition tap to the coil. This gives voltage with key on and when cranking. (has been since day one of dist. install)

But...................Now I checked the cranking voltage as suggested, and that 12v. drops to 8.5 volts when cranking! (Why?) This seems to be my problem

 

That is the source of the problem.
Take the battery and have the voltage checked while under a load.
Just because the battery is new doesn’t mean it’s still good.
Once you’ve done that, start checking all the grounds and connections from the ignition switch all through the ignition circuit.
Electrical issues are hard to diagnose, but at least this sounds like a constant issue.
If you haven’t changed anything since you last drove it, something failed, loosened up or became corroded.
At least now you know where to start.

 

Go to any FLAPS and buy one of these and see if you are getting spark at the plug.

Lisle Spark Tester

 

Voltage drops while cranking because starter uses that much current. This is normal and not your problem.
Fuel? the right amount? Are plugs now fouled from not getting spark before? Now you may have repaired the issue but never changed the plugs.
Spark? do you indeed have spark? At the plugs? Is it hitting at the right time? Timing chain jumped?
Basic Troubleshooting.

 

That tool should be carried in every C3, every classic car, every hot rod of old.
Put one of these in the rear compartment. Not in your shop, not laying in the garage, not in the house, but in the car.
Instantly know if you have "juice" or not.

Can also be found on Ebay $5- $7.

Here are a couple of quick tests for your issue:
Loosen distributor cap clamps and lay the cap over on its side. You may have to remove a few plug-wires.
Take a dry paper towel and scrub the inside of the cap. Notice the black residue on the towel? That's carbon tracking.
That can cause the spark to jump all over the place inside the cap. The spark may connect to the correct terminal. May not.
Replace cap, tighten clamps.
Then grab a hold of the entire dizzy and check for rotational movement.
Sometimes after setting the timing, the dist clamp bolt is never tightened completely.

 

Thanks, all, for your suggestions and advice. The distributor cap (and rotor, coil , and module) are brand new (HEI), no carbon deposits. Dizzy clamp bolt is tight. Battery is excellent, new, tests great under load. Bought a new spark tester at Harbor Freight today..........
This one......




Next thing to check is spark......this should tell me a lot........ I will also change or clean plugs, as they are no doubt fouled by now, also check carb float level.........and go from there....

 

Really like that tester but.
Keep in mind it will tell you if the cap, rotor, modge, coil and plug wire are working.
But it will NOT tell you if the plug is actually firing.

Another great tool that does tell you if a cylinder is firing would be a Thermo-Temp-Gun.

 

Well, finally, and it seems it was something simple. In fact, I feel dumb I didn't check or consider this earlier. I checked the valves, using the TDC method and they were lining up as they should, and lash was perfect (good, no jumped timing). After using the spark tester, it showed spark getting to the plugs. OK, now to the plugs themselves......all were fouled big time. Ok, in went a set of brand new AC Delcos. Turned the key, and varoom!! Started right up. I guess there's not an ignition on earth that could have fired up those bad plugs. I reset timing and carb float level and all is well again. Glad it was nothing serious.

 

Another note. I have a ProSystems 1040 cfm carb. It seems I had the float level set too high. I reset it to 25% of the sight glass as ProSystems advises. If it's set at 50%, like I previously had it, and how most Holley info advises, I found out it will pour raw fuel into the engine......no doubt the reason for my fouled plugs.