Guys,

I've been trying to work the final bugs out of my freshly restored '69 so I can actually drive it and I keep getting stranded due to an unusual issue. Car starts fine cold. I'll let it heat up in the driveway to about 190 degrees and drive around my neighborhood for about 20-30 minutes and the car starts running a little rough- like it wants to stall or it's missing a little. The temperature is usually coming down slightly as I drive. After it actually does stall it's impossible to start- starter won't crank the motor. If I'm running all 4 headlights and accessories it happens even faster. I let the car sit in the driveway for a few hours and it starts right back-up- only to do the same thing again if I go for a drive.

I think I may have a heat soak problem with the starter which makes the car hard to restart, but why does the car always start running rough and then just die on me. It literally drives PERFECT until the last few minutes before it stalls!!

The car is a 1969 427 390HP automatic car with refurbished Transistorized Ignition and a solid state board (all by TI Specialties), and a mild comp cam 274H. I'm running the original quadra-jet which has also been fully restored on the stock intake manifold. No headers, stock exh. manifolds.

Charging System Checks
- Battery Voltage when stranded - 12.68 Volts
- Alternator Red Terminal to frame - 14.19 Volts
- Battery Voltage No Acc. - 13.99 Volts
- Battery Voltage Acc. ON - 13.43 Volts

Other Checks
New Walmart Battery (I know) - Load tested fine at Autozone today 600/750cc amps.
Alternator - Restored 65 amp for big block/TI car (Voltage cited above)
Starter - Restored stock starter (no other checks). Factory style heat shield in place!!
Timing - 6 degrees initial (no vac adv. hooked up and 26 once the distributor comes in. (Vac adv should be another 8 at high RPMs)

 

Sounds like you have a few issues going on here. If the STARTER will not crank after a run, its usually heat related. Im mean NOTHING, turn the key and all you hear is one Rrrr......and then nothing. Thats usually heat/starter related.

Now, the 'runs fine until lit warms up' sounds like either a choke issue (85% chance) or an intake manifold leak issue (15%)

Who rebuilt your q-jet? Q-jets are GREAT carbs but will act like possessed demons if they have been dicked with or improperly rebuilt. It doesnt take much to throw them off. One of the reasons Edelbrock carbs are so popular are because the average guy cant tune a Qjet and winds up doing more damage than good.

 

Coil could be dying on you...

 

Take a look at the wiring harness to the coil and the entire TI. That system still uses the resistance wire in the harness. Years ago, that resistance wire would break and the symptoms are exactly as you describe. Run fine for quite a while and then die.
And check the ground from the right motor mount stand to the block. If that cable is internally corroded it can have high resistance and be the cause of your hard start when it's hot. Same for the rest of the battery cables.

 

It's very likely your ignition switch is shot. When the brass slides inside the switches get real worn from many years of use they get hot after a while then they fail to pass current. Which would mean your ignition would shut off as well as the ability to crank the engine. So I recommend replacing the switch based on its old age alone.

 

My 67' 390/427 did that. Turned out to be a stuck exhaust......what's the name of that valve that closes off one exhaust when cold........ Anyway, ran great cold.......stumbled like hell hot.

Oh yea! Heat riser.

 

I would 2nd the coil - not an expensive item and simple to swap. I would pick up a new coil and eliminate that as a possibility.

It likely isn't starter heat soak, as that wouldn't cause a miss and typically just becomes apparant when you shut off the engine and try to restart.

Could be something else, too, but start with the simple stuff.

 

I would also suspect the coil and then I would go over the TI and related wiring.

 

I'd also check the grounding point for the TI at the rad support.

 

I had nothing but problems from my TI Specialties coil on our 65’ 396. Car would run great for 20-30 mins, then start a random misfire...then it would get so bad, the car would try to and sometimes die at idle. I could put the oem TI coil in it from our 66’ and it would drive fine. TI specialties sent me 2 different replacement coils, all 3 did it. 52 year old GM coil works fine. My dad ended up getting an NOS coil for it and it has been fine.

In my opinion, the TI Specialties stuff is over priced junk. Had problems with a TI box and the TI repro spark plug wires causing weird misfires etc.

Ofcourse the has nothing to do with your car not wanting to even turn over on a hot start, that sounds like a starter heat soak problem or too much initial timing, but you mentioned both are fine. Check your battery cables/grounds etc real well. Make sure all grounds are in place.