302/5.0 Tech Help?

Anything's appreciated here:

I've got a seasoned '87-'93 5.0 that starts up great, idles well, but after running it around the block a few times, begins to sound like an old-time tractor... kind of "putting," if you will.

Give it some time to cool down, start it up again, and it's fine. Run it around the block and we're back to the tractor effect.

Any ideas?

*I just replaced the dist. cap, rotor, plugs, and wires. It uses a PerTronix ignition module. Vacuum may not be absolutely optimal due to some old, bad lines. It did this before I did the plugs, wires, cap, and rotor.

 

Are you getting enough fuel pressure? Install a gauge (even a temporary one) where you can see it while driving.

 

Do you have a ballast resistor installed for your ignition? I had similar problems in my Galaxie when I changed to Ford Duraspark ignition. There was actually a factory ballast resistor wire in the dash and I had another ballast resistor inline near the engine. Too much voltage drop caused the car to run like crap. Removed the ballast resistor and it ran like a top!



Malcolm

 

daddio211: I'll see what I can do.
Malcolm: Good question - I'll have to check the dash.

 

Anybody else?

 

valve hanging open. if an exhaust valve sticks open, it will make a putting sound from the exhaust.

 

Pull and check your plugs? Gap good? Did you do the wires correctly? Make proper contact? Leave a vac line off? Sounds like support and not mechanical, odd that it runs OK then runs like crap.

 

fuel line to close to the header or something cause gass to heat up and Vapor lock?? where is your temp at when it starts having issues?

 

Time for a compression check. You may have a valve seat or guide problem. This test will tell you where.

 

Good plans - I'll run them all down.

Thanks!

 

The timing for a 5L HO is not the same as a 302

 

check the coil.

 

I'm going to assume this isn't in a Mustang or anything new. Check to make sure you have a vented gas cap or that the tank vent isn't plugged. It will act just like a vapor locked fuel line. Just a thought.

 

That's a great point.

 

Hey,

Does your 5.0 still run the EFI? '85-92 Mustang HO motors were all EFI originally. Are you runnin the computer and oem wires to the cold start sensors? HO motors distributors run counterclock wise to 260,289 & non HO 302 engines.

 

It was a long block install. Simple, old school, naturally aspirated with a PerTronix ignitor module.

This is a recent issue.

 

Did you ever figure out the problem?

 

Sorry for the delay.

Yes, figured a solution: pulled the motor and gave it away.

Sent from my DROID device using the TJJ mobile app

 

now how are we going to sleep tonight? knowing that we'll never know what the problem was?

 

Also a bad PCV will make the exhaust loud but usually at idle.