My friend has a fresh 340 that we are trying to break the cam in. Its starts, but dies on releasing the key to run position. I am thinking its something to do with ignition in the run position. It has MSD box with stock distributor and we are using a good carb that runs.

Any ideas??

Thanks, Mike

Sounds like a problem with the ballast resistor, if you're still using it.

Unplug both terminals and make sure you have resistance through the resistor.

Since your friend is using a MSD system he no longer needs the ballast resistor. I agree with the previous post, probably the ballast resistor.

We tried unplugging the ballast resister and same result.

what year 340? if it's electronic ignition, it could be a bad pickup coil in your distributor.

i believe you have to take the blue wire off the volatge regulator and connect it to the brown wire from the ballast to get a full 12v while cranking

It is an older distributor that we have no experience with, so we will check that out. Also, I will check out the blue wire from the regulator and see if it is wired to the brown wire from the ballast. We do not need the ballast resister with MSD correct? But we can use one if we choose?

I think the ballast resister is old and I have a new one we can use to test.

no need for ballast.

Put a jumper wire across the ballast. It should keep running then. Agree you don't need a ballast with the MSD.

Funny, everyone is saying the same thing. Yet somehow it is not coming across.

Since I have to guess as to what kind of car, whether it is points or electronic pick up, i will use a 70 cuda, and will not specify points or pickup.

Healthservices, at first I did not understand that a ballast resister is not req'd for MSD system and that unplugging is same as bad ballast.

Your diagram is excellent. We will be trying a jumper wire. My friend can then decide if he wants to cut up his wires to eliminate the resister all together.

For those that asked, its a 1969 340 in a 1972 duster. Thanks to all that replied so far. I'll post later in the week how we made out.

Mike

Had the same thing on a 440 Roadrunner. Chased it for hours. Foud a bad connection on the steering column connector. First check for voltage at the coil + with the key on. Even checked ignition in ohms and it checked ok..

it could be in your ingition switch. when you go from start position and then to run position you could be loosing voltage at that point. check for voltage at each position.

have the same problem with 73 duster now and then...check wires at bulkhead...

i believe the center plug ...top wire..i think it is blue...check with test light to see if it getting power....

also...to run car..wire msd directly to battery and see if it will run

with the key on..see if there is 12 volts off the solonoid.(one that goes to coil)If you have 12 at the solonoid...see if there is somthing less at the coil if using the ballast(I agree,ballast is not needed on elec.ig) If not you may have solonoid or swithch issue. Put 12 volts to the coil and start it...if running...one of the two is the problem or a bad connection from the coil back. We used to hot wire mopars this way in the 60's...jumper wire and a screwdriver and You were on Your way

i had the same problem a few weeks ago with my Duster. The white wire from the MSD was grounding agianst the manual choke linkage. It would start then quit shortly after starting. it was taking the power from the MSD box and grounding it out. The white wire is a trigger wire and not used on mopars.