New Engine Won't Start

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clifftt

clifftt

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Humbly seeking advice and suggestions from you all... '64 273 engine, freshly machined, assembled and back in the car. Got gas, got compression, and have spark. But the spark looks weak at the spark plug. Taught myself the last couple weeks about this ignition system and how to use a voltmeter. Also found a great thread in "Engine Issues" by 69 340 last August which I found very helpful and educational.

I wonder if I have a bad starter. Prior to the rebuild the starter turned the engine over enough and the car would start. (But the engine smoked, thus the rebuild.) Now, I have a new Mopar 24 battery, measuring 12+ volts. With the ignition switched to "ON" I read 11.7V at "+" and "-" at the coil. But when I have someone turn the key to crank the engine, the current at the coil drops: "-" drops to 7V and "+" drops to 3V. At the starter relay, the red wire reads 12V with power "ON", but with the starter engaged, it drops to 9V. Yet somehow, between the relay and the coil "-" it goes from 9V to 7V.

When the motor was out, I painted the engine compartment and the bulkhead was removed. While it was out I used electric contact cleaner before plugging the bulkhead together again.

I measured the coil's primary (1.3 ohms) and secondary (9600 ohms) which are normal (according to an old Haynes Dart 6 cyl manual is have). New points, cond, cap, rotor, Mopar ignition cables. Original point-type distributor, coil, ballast resistor, starter relay, and positive battery cable (negative cable is new).

I bench measured the ignition switch out of the car with a spare battery and was measuring the same voltage coming out that was going in both "ON" and "START" so I figure that's OK.

One conclusion is the starter is old and drawing so much amperage that it sucks up a good portion of the voltage by the time it gets to the starter relay. Then it seems to drop two more volts after that. I figure everything was settled in with the old motor that the engine and the ignition system co-existed nicely. But now with a new tight motor everything is having to work harder and the ignition system is strained.

I have two things left to try: scraping paint off the engine block at the two grounding cables, and cleaning the fuse box (I noticed the fuse contacts are a bit rusty). Perhaps there's a pinched wire somewhere. My last resort is to find a shop willing to correct my mess and get this new motor started. Any help is greatly appreciated.
 
I had the SAME thing happen to me except instead of test all that stuff I went and bought a new starter (KEEP THE RECIEPT!!!!!!!!WARRANTY)
and she fired right up.

SO it wont even turn over huh?
Way to go on the Investigation and acquirement of new Voltmeter Skills!:cheers:

It may have worked before but if your new engine is making full compression now. It may be too much for the plum tuckered out unit. Especially if it is the 10.5:1 Compression engine... Like mine

Like I said Buy the thing keep your receipt on file for warranty purposes (You wont have to buy a new one for a while) and fire up that 273 BRO!!!

You deserve it
 
I like the paint scraping idea at the contact points of the cables, also do it at the grounds.

You can have all the voltage in the world, but with no aperage (electrical pressure) you got nada.

Is your block grounded to the chassis with a ground strap?
 
On the last small block I did, I had the distributor 180 degrees out. the engine would turn over but never start. check your timing

Mark 69-383 FS
 
If you have spark but it's weak, you have unwanted resistance or a poor ground. You need to find the source of the voltage drop or high resistance in the wiring. Take your voltmeter and place it at various points along the suspected wire until you reach the point of the high voltage drop; i.e., should be 12V to the point that 12v needs to get to. If you have less voltage to that point, there's your problem and you need to repair or replace the wire or connector. Try measuring on the ground side too. If you have high voltage going through somewhere that should be 0 on the ground side, then you have a bad ground.

If you have a way to measure it, perhaps look up the spec for how much current is being drawn by the starter, should be around 150+ amps. If it's drawing less, you have unwanted resistance in the wiring.

Might try whacking the the starter too too see if that helps, might be a poor ground. That's the old school way.
 
Almost sounds like a weak battery. You need 12 volts at the starter.
A good battery will stay 9.5V for atleast 20 seconds at 60 degrees.
 
You have "spark at the plugs" which tells me the engine is turning, is it turning fast enough? My thought is that timing isn't right. Go through that TDC thing, reset the distributor, and check the firing order and direction of rotation on the distributor. start over from the start and check every thing.

In a hurry, I have plugged the wires into the distributor cap in the wrong direction before and it baffled me for hours.
 
not to be a "know it all", how is the pos cable condition?
one little strand will conduct 12v, until its under load.
 
Thanks for all the replies, some good thoughts there. Yes the motor turns over, seemingly a little slow.
Cudaspaz: I'll clean up and check the grounds again.
Rtse440 / cuda65vpt: Distributor is in correctly, wires and circle of location is also correct, although I have checked a dozen times anyways. For kicks I've rotated it on two other occasions anyways.
Redfish: It's a brand new battery which I trickle charge after I fiddle with the car. But you're right, I've seen defective batteries before and I have not checked it while starting the car. Good suggestion, thanks.
Mech1nxh: The positive batter cable visually looks OK, the clamp is original, nice and clean. But for years it has run down next to the exhaust manifold and maybe resistance is an issue. Another good idea to check it out.
Rmcharger: I think I'm coming out of denial now, but I think you're idea which sounds like the most painstaking of all is the most likely culprit. The wire from the loom which runs along the right valve cover to the coil feels very stiff and the insulation is brittle. I may have to get into the loom probe that thing and may find my week point.
Madmaximum: And if all else fails, I'll probably throw money into a new starter, one of those small hi-torque ones.

Guys, I'll play with it Saturday and keep you all posted.
 
cudaspaz said:
IYou can have all the voltage in the world, but with no aperage (electrical pressure) you got nada.
Click to expand...


Not to be a nit picker but with a neophyte trying to trouble shoot a possible electrical problem it should be clear.

Voltage is analogous to pressure and Amperage is analogous to volume. A bad connection has high resistance which would be analogous to a crimp in a hose which will restrict the volume that can flow through the hose. You can increase the volume (amperage) by increasing the pressure (voltage) or decreasing the restriction (resistance).

My vote for CLIFTT would be go back and verify the timing. If the engine is cranking over and there is a spark and there is fuel it should start or at least be making sounds like it wants to start.
 
My first thought was dist out 180 deg's.

On the mini starter. Go to a junk yard and get one. My last one cost me $12.00, and looks and works like a brand new one.
 
Too much initial timing will out a huge draw on the starter. Make sure it's timed right, maybe even dial the initial back and see if it spins more freely and feed timing into it until it starts.

You really don't want to spin an engine too much that needs a camshaft broken in.

The voltage at the coil is wacky. What type of ignition are you running. If it's an MP set up, it's should have 6-8 volts in run and ~12 volts cranking as the ballast is bypassed. The draw from the starter could be taxing the entire system.

Good suggestion on the mini starter. I run junkyard specials all the time, never had one fail yet. A little powerwashing clean up and they are good to go.
 
I had a similar problem once, turned out to be I had 2 bad spark plug wires... about pulled all my hair out. have you tried doing this in the dark? can you see anything arching?

-j
 
Crackedback & Johnny Dart: I could probably find me a starter and a cheap starter certainly won't hurt the wallet. Jeh: I've actually dimmed the lights to check the spark on the ONE cable I had out, which is how I believe it looks weak (white spark and not blue). But the spark plugs are new and the cables are new and each made a 'snap' as I made the connection.
Again, thanks for your suggestions, I'm gonna' focus on this full time tomorrow, occasionally check back with you, and cross my fingers!
 
Same thing happend to me and it turned out to be the starter. It had a short in it.
Take it out and have it tested. It won't cost you anything and then you can rule it out if it's good.
 
I found a 2V drop between the bulkhead connectors at the dark blue wire going to the ballast resistor/coil late yesterday I was trying to figure the logic of it while interpreting the wiring diagram.
Then she called for dinner.......
I'll tackle it later today, but at least it keeps my spirits up that I think I'm on to something.
 
Crackedback, you're right about the voltage at the coil, I got the figures backwards.
This is a stock ignition system, stock distributor with points.
With ignition switch on, I am reading at the coil "+" and "-" almost 12V.
When I crank the engine over, I read at the coil "+" 8V and at the coil "-" 3V going to the distributor.
With the ignition switch at "start", shouldn't I get the same reading at "+" and "-" (in this case 8V), then when the car starts the ballast resistor kicks in and "-" drops to 3V?
Visually the spark coming out of the coil cable and also to a grounded spark plug look weak, kinda yellowish.
 
Bad ground in the distributor. Convert to electronic. You wont be sorry.
 
At some point I'd like to switch to electronic. Right now, if possible, I want to limit the variables. Based on your idea needsaresto, I'll pull the distributor and check it out. Maybe somethng funky is going on with the way I installed the points and condenser.
 
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