coldfire

Car died today (1970 Cutlass S 350)

Was driving and out of nowhere my tach started skipping all over the place & then the car just died.

It will refire, but only revs once and then immediately dies again

I am clueless here, but my guess is timing chain???

oldcutlass

Disconnect your battery, pull your spark plugs out, and remove the distributor cap but leave the rotor on. With a breaker bar and a socket on the crank bolt, turn the engine back and forth and see how far you can turn the crank before the rotor turns.

What distributor are you running? Do you think it may be ignition related and not your timing set?

svnt442

What are you running for a distributor?
My feeling is that if the timing chain caused it then the car wouldn't restart....not easily anyway.
Another thing to check...if you can get it to idle....is to look for a vacuum leak. Sounds dumb, but if the brake booster picked that moment to fail, that would cause a HUGE vacuum leak and could cause it to die.

coldfire

The car died about a mile from my parents' house (where I was heading at the time) so I left it there for the time being, can't check on anything right now or probably for a few days even

It has an HEI distributor in it - the cap & rotor were replaced about 1000 miles ago. I have been planning to replace the ignition coil as well - hadn't gotten around to it, could that be a possible cause?

oldcutlass

Anythings possible, you are going to have to do some troubleshooting. Make sure you have voltage at the distributor, spark, fuel, etc...

svnt442

I've had some funky things go on with HEI's in the past. In my 76 Salon I kept an extra module in the glove box and when the car would die I would just swap them and be on my way. When it would die again....the one that I removed the last time would go back in and I'd be on my way again. I never did figure out what the problem was with that car, but the swapping was working as I was broke and it only took 2 or 3 minutes to swap them and I really didn't care.
If the coil went out it would stay out, not come back and die again.

coldfire

We couldn't get it to idle, it really will only fire once and then dies regardless of what I do with the throttle

Would there have been other symptoms of the brake booster failing as I was driving? And would it have caused my tachometer to spas out the way it did?

coldfire

Sorry, but what part is the module?

oldstata

null-35.jpg

Module
The tack could have been jumping around as the engine was dying out .
Module is one reason people like to keep the old points distributors .
They are cheap and a easy fix but thay go out at the worst times

don71

Yea, that part right where his thumb is> held in by two screws. I keep one in the glove box too.

Like mentioned, you need to check for spark. You got fuel squirting in carb right? Then do what oldcutlass said in his first post to rule out the timing chain.

ThePackRat

Make sure you use a heat paste under the module if you find yourself replacing it.

Otherwise they will heat up & go bad in no time.

m371961

Does it fire and start to run when the key is in start position, then die when key returns to run? For a quick test run a 12 volt jumper from battery to coil.

MDchanic

It's HEI, so the wire would be from the battery to the BAT terminal on the HEI.

Because of the tach jumping around, I would go with an electrical problem first.

HEI components - module or pickup - are high on the list, but so is the tach itself.
I've had a bad tach that behaved that way.

Try unplugging the tach from the HEI and see what happens - easy enough to do.

- Eric

Oldsmaniac

If the timing chain has "jumped" often while cranking the engine to start you will notice a different sound as if the engine has little compression. Also you may notice fuel vapor being expelled from the carb rather than a draw thru the carb. You should also check the leads from the pickup coil in the HEI distributer. From age these can crack causing an intermittent non fire condition.

joe_padavano

It's extremely easy to check for a slipped timing chain. Simply use a timing light to check the timing mark while you crank the engine. If it's way off, the chain is bad. If the light won't flash, it's probably distributor.

coldfire

Can a bad tachometer actually stop the car from running?

oldcutlass

Yes, you can just unplug it and see.

MDchanic

Happened to me in a '68 Galaxie with a $2 swap meet tach (Damned swindler).

- Eric

coldfire

Tried disconnecting the tach - same symptoms

I did note as someone above suggested, that it will run if I leave the key in the start position & dies when returned to on position

oldcutlass

Run a jumper wire from the battery directly to the batt terminal of the hei and see if it will stay running. If it does, then you lost power to the distributor with the key on. To turn it off remove the jumper.

Octania

perform the above troubleshoot by hotwiring 12 right to the HEI.

If your new wire runs the engine fine, then your trouble is in the ign switch circuit. Probably the ign switch itself but could be any of the wires to and from.

coldfire

Yup! Power straight from the battery & she stayed running!

...so where then is the issue likely, what am I bypassing that's bad?

MDchanic

That sounds like an ignition switch problem, then, or a problem in the Run circuit (pink wire from ignition to firewall, then resistor wire). .
The '70 ignition switch should contact both the Start and Run circuits when cranking, unlike the mid-sixties switches.
If there is a break in the Run circuit, you could be back feeding the coil through the yellow wire from the solenoid while cranking, then it disconnects when you release the switch.

- Eric

coldfire

Beat me by a second! You mean the switch that's in the steering column?

joe_padavano

To recap, you have a 70 Cutlass that was converted to HEI. Presumably someone bypassed the resistor wire from the ignition switch to the coil to provide full 12V to the HEI. Look for this wire (and the splices used on it) as the source of the problem.

MDchanic

Yeah, sorry I forgot about the HEI bit - posting from cell phone at work, tiny screen.

Connection is to HEI, not coil, and there should be no resistor wire now.

Look for PO dumb stuff as Joe said.

- Eric

coldfire

This was it!

I back-tracked the wire from the ignition coil to where it had been spliced in, unwrapped (un-crumbled is more accurate) the old electrical tape and the wires had just been twisted together and were corroded.

Luckily, there was enough length in the wires that I could cut back, re-strip and use actual wire connectors

Thanks a MILLION to everyone who posted - I was convinced that this was going to be a major fix/expense

MDchanic

You're welcome.

Sorry I got confused about what was going on earlier, but when I'm responding on my phone, I can't see a darned thing on that tiny screen.

Glad you got it fixed!

By the way, you mention "wire connectors" - I would strongly recommend soldering and shrink tubing, especially for vital connections like this, where you want full current and reliable operation.

- Eric

m371961

I would check the voltage to make sure the resistor wire was completely eliminated.
And I agree with MD, solder and shrink wrap that connection.

joe_padavano

You might want to review the formula for calculating resistors in parallel. Running the new wire in parallel with the existing resistor wire actually results in LOWER total resistance than just running the new wire by itself. Of course, simply replacing the resistor wire works fine.

As for connectors, DO NOT use the blue 3M Scotchlock connectors. These things are so unreliable they should be banned.

m371961

Just concerned the PO just added a pigtail to the original resistor wire then connected the HEI.

oldcutlass

Glad it's fixed!

joe_padavano

Gotcha. Hadn't considered that possibility.

droldsmorland

For a permanent weather/moisture tight connection you can also use the high quality (properly sized for the wire) butt splices that shrink with heat. They have glue in them to provide a great seal. AMP, Beldon are two sources. A good NAPA will carry them. If you'd rather do the solder thing get the heat shrink with the glue if you can find it. I don't particularly like heat shrink around engine heat unless its the HD thicker stuff. The thin wall stuff tends to split if close enough to the heat over time.
As for the connection to the distributor I usually run a direct 12 VDC "keyed" source off the fuse block directly to the terminal on the cap then tie up the original resistor wire and hide it in with the original harness if one ever decided to swap the points dist. Use a high quality automotive grade 12 gauge stranded wire. Dont skimp on the wire.
Scotchlocks are for HACKS! Though its a step up from the hack job you found.

coldfire

FWIW I used one of those wire nuts or whatever they're called (twist the wires together and then screw it over)

I would actually love to just run all new wire under the hood. I'm gonna try to look at AAW kits when I get the chance - or any other complete wiring harness setups (if any suggestions)

m371961

Ugh, thats worse then properly used Scotchlocks.

oldcutlass

A few inch length of resistor wire with a pigtail won't harm any thing.

MDchanic

+1.

Don't even tell us that, unless you're also telling us that you ran 10ga wire through galvanized conduit to a weatherproof box.

- Eric