Ignition timing likely cause of reduced power in '71 Duster

BY . Dec 08 04:00 am

Question: I have owned a 1971 Duster 340 since 1973 and it has been parked for 25 years. I am now rebuilding it.

Before I parked it I knew it didn’t have the same power it used to. I had the motor rebuilt and they installed a used piston but still not the power. I installed a rebuilt transmission and still not the power. I have a dual point ignition which we never changed. Some people are telling me to go to electronic ignition but I would rather stay original. What do you think?

Franklin

 

Answer: You have a great collector car, and I would suggest you keep it original with one exception.

If you are only going to drive it occasionally, the point-type ignition system will work fine, but if you want to drive it fairly often I would suggest going with a newer (mid-to-late 1970s) electronic ignition system. This would involve changing the distributor, adding the electronic ignition module and a small wiring harness.

All this can be done without modifying the rest of the car, so you can easily swap back to the original parts. The electronic system will start and idle better.

As for the decrease in power, the 1971 Duster 340 engine had high-compression 10.25-to-one pistons, lowered in 1972 to nine-to-one compression because of lower-fuel octane ratings. I suspect the ignition timing on your car has been retarded to help prevent engine-damaging pre-ignition from the lower octane fuel and this is what is giving you the decrease in power. A worn timing chain will also cause a feeling of lower power when pulling away from a stop, so be sure to have it checked, too. Unless you want to run the vehicle on premium fuel and add some octane booster to every tank, it is better to keep the timing retarded. The 340 engine is still plenty quick and a fun car to drive.

If you want really fast, buy a new Dodge Demon. Personally, I would rather drive your Duster.

 

james.kerr@sasktel.net