I have a 71 ols 98 with a 425 motor that was rebuilt in marach. It has a HEI districutor. Car was running and after maybe 5 min it cuts off. Did some checking and took wire off number 1 plug and put a spare plug in wire to see if i had spark and nothing. Redplaced ignition coil, ignition module, wires, and plugs. I definetly have roughly 10.5v going into distributor. Any ideas why i have no spark at the plugs? I Also checked the magnetcoil resistance in the distributor and it was 830 ohms. Should be normal. I'm out of ideas can anyone help?

 

Is your distributor cap and rotor in good shape?

 

Yes I took the distributor cap off and there was a little residue in the tips inside the cap so i brusked them off. I also brushed off the tip of the rotor cap. the distributor was new and was put in in march 08. the rebuilt motor has only 10k miles on it.

 

The rotor can develop a "short" that will carry all spark to the distributor shaft. Try a new one. Good luck.

 

HEI requires 12 volts...why 10.5?....dont know if that would be the problem but it would be a good place to start.

 

While cranking, the voltage supply could easily be 10.5, if not less. when the engine is running, and the alternator is charging, one should expect it to be in the thirteens, or higher.

Norm

 

Okay i rechecked the voltage going to the distributor and it is 10.3. I changed the rotor and cap and still no spark. I'm at a loss. I checked the vacumm lines and no leakes there and it is also getting plenty of gas and trying to turn over. Anyone have any ideas?

 

If you can get a service manual for the car. Their is a chart to help you diagnose the HEI system. I have one but it is to hard to explain exactly what to test, and I dont have a scanner to post it on here. From reading what you have checked it comes down to the vacuum advance and the pickup coil. It says nothing about having to replace the distributor, dont waste your money on that just yet.

 

Thanks dan and everyone. here is an update this seems a little unsual.after my changed the rotor and cap i decided to take a stab at oldsmanic's idea of not haveing a full 12 volts. what i did was make a jumper from my battery to the districutor and measured the voltage as 12.8v. then unplugged a wire and put in a spare spark plug to check to see if i had a spark and still nothing. i put the wire back in the plug connecter to my motor and tried to start the car and poof it started. It stayed started united i disconnected the jumper wire. After that i connected the distributor wire back to the wire that routes to my firewall eveentually and started the car and it started again. i let it run for 15 min. i shut it off and checked the voltage to the distributor with the ing in in the start position and it measure 10.9v with was diff from the original non starting voltage of 10.3v. It's stragne that i never saw a spark but the car started. in the mist of everything i lost the butterfly nut that goes to the air filter housing. i'm going to find a nut and dirive it a bit.

Question: now do i need to replace the power wire that goes to the distributor? Is this the wire that had the resistor in it? maybe that's what's pulling the voltage down a volt or so.

 

I hope you dont have a resistor or resistor wire going up to the distributor , right?

 

Did the car originally not come with hei? If it did not the car probably has a resistor that is probably keeping your voltage so low. I am pretty sure that the points systems needs less voltage to keep the points from burning up. HEI needs a full 12 volts to operate correctly. What I would suggest to do that is not a hack job is to run a wire from the pink wire going into the ign switch to the 12v terminal on the distributor and if you can try and get rid of the old power source for the dist.

 

I will do. I'm pretty electrical savy(electrical engineer) so i think that i can handle that part. Thanks for all your help. I'm going to drive the car around tomorrow and hopefilly i'll be okay(if not i still have the jumper wire) . I'll also take some pics and post em when the rain stops. Hopefully you guys can appreciate one of the few 4 door dinosaur olds out there driving.

 

And to reply to dan...there was an original points dist and it was changed to a HEI and that wire was never changed and it is being used. That seems to be the problem.

 

Good luck! Now I need to get my own engine running.

 

I tryed to post a pic or two but i got an error when i tried to attach a pic thru manage attachments.any ideas?