What's the correct firing order and ignition timing on a 1973 Buick Centurion 350-4
Asked by froeschl Jan 02, 2018 at 02:25 PM about the 1973 Buick LeSabre
Question type: Maintenance & Repair
My '73 Buick Centurion has severe start-up problems. At the moment I'm not able to get the engine started at all - not even using jumpstart fluid (sprayed into vacuum hose connected to master brake cylinder). Ignition basically works; ballast resistor seems to be OK, too. Also fuel is being delivered to carburetor. So either there is an air problem or bad ignition timing. Ideas very welcome.
5 Answers
Firing order: http://www.tpocr.com/buick1.html
Firing order is 1-8-4-3-6-5-7-2 which is standard for most GM V-8s. Timing should be 4 degrees BTDC.
oldcarpenter answered 6 years ago
If you have a "cranks but no start " problem, why would you think the timing is that far off" Spark at the plugs? you say you have fuel....take air cleaner off, will solve the "maybe an air problem" a little more info would be helpful....was it running and all of a sudden this happened? was it running and it got worse? if you can be more detailed on how this issue came to be, someone here maybe able you point you in the right direction....
Getting the car started (cold start after a couple of days or weeks) has always been a "lottery" since I bought the car 2 years ago. However, once the engine is running, it runs rather smoothly and re-starting a hot engine is no problem. But getting the cold engine running is often a challenge. Sometimes it works, sometimes it doesn't - even in summer. Normally I pump the gas pedal 3 times before I try to start the car. During cranking I do not touch the gas pedal. When it does not start initially, I press the gas pedal once again and try to start the second time. That I do up to 4 times. If car does not start at 4th trial, I will need to re-charge the battery. Quite often even the 5th, 6th or 7th startup trial are not successful like at the moment. I've been trying this a couple of times during the past few days - no chance, car does not attempt to start. Spark is there (tested with separate spark plug), fuel is also there. So for my understanding it may only be an improper ignition timing (too early or too late which is rather unlikely as the car has been running properly not long time ago) or the air-fuel ratio is not good. Even jumpstart fluid does not help. Now ???
I think your problem is fuel delivery, not timing. Try a capful of gas down the throttle plates instead of starting fluid. You could also check vacuum advance on distributor. The accelerator pump on these carbs needs to be in good order, with a good diaphragm or you won't get the fuel you need. Your engine if I recall does have a lot of vacuum lines, so check you don't have a vacuum leak letting air in where you don't need it.
