timing- this seems odd

[bryonbush 85]

so ive been having some issues lately that come along after about 20 min of driving. long story short, i was told to check the timing again. went out there just now with my light and at idle, its at 30 BTDC ?!?!!?

 

so i went back to my old emails with the engine builder and he said that it was set at 6* advance but will need to be dialed in. the local mustang shop who finished the engine swap for me said they set the timing. when i got it back it was pinging under load so i brought it back enough to stop. Seems to drive fine, but after 20 min of driving, the thing starts stalling and losing power. (there is a whole different tread on this on VMF) http://forums.vintage-mustang.com/vintage-mustang-forum/893138-seriously-dont-know-what-do-2.html

 

with that said, this cant be right. kicker is, it starts right up and drives fine, (for about 20 min before the trouble acts up) so not sure what to think or even do at this point.

[danno 128]

I wonder if the timing issue is a phantom problem.  There is nothing about timing that will change when the car is warmed up.  You have a problem not related to timing.  Maybe it is running too lean, and when it is warming up the choke is closed and you do not see the problem?

[1969_Mach1 333]

Just a thought.  I had a Holley 750 vac secondary carb that would act up after driving about 30 minutes.  What would happen is the engine would no longer idle.  It would simply run extremely rough at low speed then shut off at idle.  Let the motor sit for 20 minutes or so and it would be fine again.  I ultimately replaced the carb to fix it but now I realize it could have been debree floating around in the idle passages and occasionally plugging an idle restrictor in the metering block.

 

Make certain you have adequate air cleaner lid to carb clearance.  I don't know how critical it is but Holley recommends 1" between top of choke horn/vent tubes and air cleaner lid.

 

Have you ruled out vapor lock from the fuel line between the fuel pump and carburetor getting too hot?

[bryonbush 85]

im going to link this on going battle that i posted on VMF about this too http://forums.vintage-mustang.com/vintage-mustang-forum/893138-seriously-dont-know-what-do.html

 

if you dont want to read through that, here's what ive done so far. New fuel lines, filter, carb spacer, new carb, and new coil.

the symptoms were happening with my edelbrock carb as well before i went to the new holley. at this point im starting to think that this is now an MSD box issue due to the fact that i have changed everything else. starts fine runs good, then it happens after driving a while. heck just got back from a 12 mile drive and on the way back, it started again. this is a used box i bought from a guy off another forum and im really starting to wonder if this is why it was sold. 

[1969_Mach1 333]

The only other thing I can think of at this time is are you using a true 12V source for the switched power to the MSD box.  Some people mistakenly use the wire that went to the original coil but that is connected through a resistor wire.  If that is correct, it could be that used MSD box you purchased.  There is still the pick up coil inside the distributor.  When those go bad it is usually temperature sensitive.

[TheRktmn 15]

Shooting in the dark here, but how is the vacuum advance hooked up?  If it is connected through the timed port on the thermostat housing it may beconnected wrong i.e getting full advance when the motor is warm and ported when it's cold. I don't think they started using them until the early 70s, but there's no telling what a previous owner may have done or if it was a CA car and has the early emissions set up on it.

Have you checked that the mechaincal advance weights or plate inside the distributor isn't sticking?

The MSD will work fine if you're using the coil+ or Solenoid IGN wires as the on/off power source. The large red power wire needs be connected directly to the battery.

 

Edit - why are these thumbnails in my post.....?

[Gomach1 12]

Ditto on rev counters thoughts. next time it does it disconnect distributor vacuum and see if returns to normal if so check vacuum source, if not tap on side of distributor.

Not my thumbnails!!!

[Gomach1 12]

Not my thumbnails!!!

[jholmes217 65]

What material is your carb spacer made of?  Wood is the best for insulating the carb from heat.

[bryonbush 85]

distributor is a billet one so no vacuum hook up and the carb spacer is wood. power to the msd box is all correct as well.

[1969_Mach1 333]

Cracked wood carb spacer?  Other than that the possible components are narrowing down to the MSD box or the pick up coil inside the distributor.

[bryonbush 85]

Wood spacer is good. I'm going to check the dist and see how the ohms check out today. Going to pick up a new Box from a guy tonight so we'll see what happens

[barnett468 418]

disconnect and plug your vacuum advance and leave it plugged until prob is solved.

 

set initial timing to 10 degrees btdc.

 

tighten distributor but make sure the bolt is not bottoming out.

 

if you have a holley or quick fuel carb, set the gas level so it is just below the inspection windows at idle . . if you have plastic windows, they must be removed to do this.

 

reset fuel mix screws.

 

take timing lite with you and check timing if it happens again.

[bryonbush 85]

So just now, i went out there with my multi-meter to check the resistance on the distributor. the only way i could get any reading was to turn the meter down to the 200 setting and then i got a .3 reading. the picture MSD uses on their page for instructions shows their meter at 20K. i couldnt even get a reading at 2K let alone 20K! resistance should be within 500-700 and im not even close.

[1969_Mach1 333]

Sounds like its worth replacing the pick up coil (or whatever MSD calls it).  At least its a lot less expensive than a new MSD ignition box.  Worse case is you'll have to call MSD and buy it direct from them.  I've ordered several parts direct from them.  They have good customer service.