I have a '73 Plymouth Valiant. It hasn't been well taken care of but it runs pretty well. I have a problem though with it hesitating really bad either warmed up or cold. I live in Hawaii so it is always "warm" outside so nothing to worry about with cold, cold starts. I had the timing looked at and it is perfect. The card is kinda black but I spray carb clean in now and then. I noticed today that it blew out black smoke. Does that mean burning oil? The car doesn't have too much serious rust but the engine needs to be de-greased and given some TLC. The '73 is ugly but damn if I don't love these ugly cars. I know if you love your Slant Six she'll last a long while but what could cause the hesitation? Fuel pump maybe? Any ideas?
Thanks for the advice.

bigounets@wwdb.org

Oil smoke is blue. Black is "running rich, too much gas" smoke. I suspect the carb needs to be rebuilt. You might improve things by taking the carb off the manifold and submerging it in a bucket of carb cleaner for a few hours, but rebuilding would be better.


dwordinger@earthlink.net

My first "guess" is that the distributor's vacuum advance "pod" is blown or there is some other problem preventing the vacuum advance from pulling in quickly. To test this, put a timing light on the mark and work the throttle by hand, the mark should "jump" forward 10º or more as you "crack" the throttle open. Disconnect the vacum advance hose and retest, if you see no difference, you have found the problem. You may want to run a vac. advance hose directly from "ported vacuum" to the distributor if it is not already routed like that.

Another note: try advancing the timing to 8 -10º BTDC, this will also help reduce any off idle stumble.
DD