Vatchy

I have a carbureted 1985 GT with about 164K miles. When the car is at normal operating temperature, and it is turned off, it will not start again. It sounds like the battery is almost dead with the engine just barely turning. If I let it sit for 10 minutes or more, then it will start normally. I have replaced both of the battery cables - positive and negative with the thickest ones I could find (Napa). I have replaced the solenoid-to-starter cable. I have replaced the starter with a Summit Protorque starter. I added a heat shield to the starter. Following the instructions that came with the starter, I have bypassed the starter portion of the fender-mounted solenoid and I am using the solenoid in the starter itself. I have replaced the alternator with a Powermaster 140amp alternator. The battery is about 1.5 years old and I have had it tested twice at two different shops and it shows good.

The engine is getting very tired. I am getting oil on two spark plugs (1&8). It feels sluggish so I think that the timing chain has stretched and needs replacing. 55k miles ago I had a three-angle valve job done and added Crane 1.72 roller rockers (Cobra).

It starts fine when it is cold or when it has sat for 10-15 minutes. It will also push-start very easily when the starter won't turn the engine.

This is driving me crazy!!! Any help would be appreciated.

Derf00

Could be a number of things.
Butterfly mechanism for Choke could be getting stuck closed on the carb: Replace the carbureator choke
Ground points could be rusted. You replaced the cables but did you clean the grounding points?
Ignition switch could be cracked and allowing voltage leak.

turbostang21

interesting....my buddy has been having this EXACT same problem with his fairly new built 306. he/we have replaced everything you have + a borrowed carb and rediculous things like intake gaskets (someone told him...don't ask me). well we still haven't figured it out so i'm very interested in some ideas as well...he just doesn't shut it off until he gets home it's not his dd.

Vatchy

No, I did not clean the ground mounting point when I replaced the cable. I'll do that this weekend. How would I check for the ignition switch problem?

vfast

either the timing is high or your starter is getting heat soated...

Vatchy

The car runs fine on regular 87 unleaded so I don't think the timing is too high. Also, I bought the starter and heat shield at the same time and put the heat shield on the starter when I put it on.

Grimace5.0

Good call! My guess is timing.

blowninjected

Your starter is getting too hot..I had the same problem

vfast

they make a blanket to go over the starter......do this and you'll know next time it does it poor water on the starter..and watch what happens

Vatchy

How did you fix this problem? I have a new Protorque starter from Summit with a new heat shield and it still does it.