390 starting problems...

[RFMustangGT]

Thought I might see what some of you guys thought about the 390 in my 62 T-bird. I know it's not a Mustang but 390 is a pretty universal big block in the 60s.

I went to change the points and condenser due to the points were pretty well used. I got the car running and ran great for about 15 minutes. I shut the car off and check the points which had moved a bit so I tighten the bolt down, I clean off the timing marks and hook the timing gun up ready to set the timing. I go to start the car and it just cranks and cranks and cranks then finally hits and backfires through the carb. I assume I have moved the timing. No mater which way I turn it will not either fire or it backfires through the carb. A friend of mine who is a big block Ford guy says he thinks it sounds like the timing chain either broke or jumped a tooth. Could it also be water in the gas? I really don't want to pull motor out but it's starting to look like I will be. Any ideas on possible problems?

 

[Tim65GT]

Remove the distributor cap and check to make sure the rotor is rotating while cranking. If the timing chain is broke the distributor would not rotate. If it skipped a tooth, that would be a bit more difficult to check. You could do a compression check. That would indicate something is wrong with the mechanical timing.

Are you getting spark? Pull off a plug wire & see iff the spark jumps to ground when cranking. Maybe the points closed or opened up somehow.

Was the car sitting for a while? If you suspect water in the gas, maybe you should drain the tank and put in fresh gas. Pull off the air cleaner and see if fuel is squirting into the carb venturies when you pump it. If not,check the fuel filter, it may be clogged. While it's off, crank a few times with the fuel line into a coffee can to check it flows good.

 

[RFMustangGT]

it has spark and the rotor turns. The points open and close as they should. I think this weekend I will try the coffee can gas. I have a spare carb that I might bolt on and see if I can rule out that part.

 

[D.Hearne]

First thing you really need to do also is ditch the points. If they're not set damn near perfectly, the motor will run like crap. Install any of the electronic conversion units and you'll be amazed at how easy it'll start--everytime.