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Discussion Starter #1
I have a 1967 GTO with 400/turbo 400. The wiring under the hood is not all factory correct and the engine was rebuilt around 15 years ago. I have had the car about 12 years. It has basically sat in a garage for the past 9 years. Driven but not the "extra" care a car that old needs.
For the past few years I have had a very difficult time starting the car after the engine has warmed up. It acts like a weak battery. Even with a new battery it still does it, and gets worse as the battery becomes weaker. I usually have to let it sit, allow the engine to cool down, then it will start right up. However if the battery is weak, it will not start at all. When I jump it, it will start and continue to run.
What is going on? Does the heat of the engine cause the battery cable to get too hot? Starter getting hot? Battery not strong enough? (Due to economics, I have only put an advanced silver battery.)
I really need to get this problem fixed. I finially have the time to start enjoying my car again. Thanks in advance for any help.
Brian
 

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Could also be your tune. An engine runs differently cold than hot, when it's cold you have high idle and choke, that can affect how it starts compared to when it's warm. When it's warm the carb is operating differently and if you are a bit out of time, or if the mixture is not great it can really change your ability to get it started. I agree that since it sounds/acts like battery that it could easily be starter/solenoid/battery cable but remember a car that sits needs regular starts and adjustments, you will get buildup in your carburetor, and fuel lines and crap on your plugs. Check everything since she's been sitting, cleaning and re-gapping your plugs, check the timing, take her for a cruse on the highway at 65-70 blow that crap out of her systems. It will do a world of good.
 

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Make sure your ground straps are all intact. Many times the heat soak issue is a ground problem. If the motor's been out, the straps may not have been reinstalled. Ask me how I know...:rolleyes:
 

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Discussion Starter #5
Thanks for the help. I will start with the easiest and work my way up. It did it again. I went out the other night to pick up some food, and needed to be jumped. The next morning I went out and it fired right up.
The starter on the car is an Advanced starter. Could the cheaper starter be doing it? Also, I am not sure about the ground straps. Where could I find out where the attach to? I am not very familiar with this but I do have the ability to fix it if I know what I am looking for.
Lastly, did the 67 GTO come from the factory with a heat shield around the starter?
Brian
 

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WVmtnman: you have a high resistance problem in your starting circuit. It could be in the wiring (probably is) or starter, or switch, or all of the above. I would replace the underhood wiring harness with a new one from the vendors (I just did my own '67's...what a difference) and I would check out the grounds and battery cables very carefully. resistance increases with temperature, so when it gets hot, it won't start. I had this very same problem in my '67 for years, but not anymore. I replaced the bad wire at my ignition switch (purple wire) and the underhood harness took care of the rest. Be sure that your starter and battery wires/cables are well insulated and are running thru the metal tube at the rear of the exhaust, and make sure the tube is not touching the exhaust manifold, too.
 

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Thanks for the help. I will start with the easiest and work my way up. It did it again. I went out the other night to pick up some food, and needed to be jumped. The next morning I went out and it fired right up.
The starter on the car is an Advanced starter. Could the cheaper starter be doing it? Also, I am not sure about the ground straps. Where could I find out where the attach to? I am not very familiar with this but I do have the ability to fix it if I know what I am looking for.
Lastly, did the 67 GTO come from the factory with a heat shield around the starter?
Brian
its not ground straps. the starter is grounded directly to the ground cable. yes it could be the starter. make sure you have a hi torque starter and its not dragging.
 

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I've never seen a ground cable connected to the starter on any GTO. Mine have all been grounded at the fender to rh wheel well, the firewall to back of the head, and the back of the engine to firewall...along with the negative batt cable to the head bolt. The starter gets its ground thru its mounting to the block, and the block and chassis need to be grounded to each other to work properly. That said, it very well could be a bad starter.....I would replace the already mentioned spliced/worn wiring, and while that was being done, remove the starter and take it to an old time rebuilder for a check out. This is a 44 year old car....to be reliable, it has to be repaired/checked thoroughly....
 

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I've never seen a ground cable connected to the starter on any GTO. Mine have all been grounded at the fender to rh wheel well, the firewall to back of the head, and the back of the engine to firewall...along with the negative batt cable to the head bolt. The starter gets its ground thru its mounting to the block, and the block and chassis need to be grounded to each other to work properly. That said, it very well could be a bad starter.....I would replace the already mentioned spliced/worn wiring, and while that was being done, remove the starter and take it to an old time rebuilder for a check out. This is a 44 year old car....to be reliable, it has to be repaired/checked thoroughly....
part of electrical trouble shooting is thinking it through. the starter is directly connected to the block which is directly connected to the ground cable that is bolted to the head bolt. the positive cable is directly connected to the starter. when the starter is engaged it makes a complete circuit. the body ground straps do not come into the equation so we can eliminate that as the problem.
 

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I've never seen a ground cable connected to the starter on any GTO. Mine have all been grounded at the fender to rh wheel well, the firewall to back of the head, and the back of the engine to firewall...along with the negative batt cable to the head bolt. The starter gets its ground thru its mounting to the block, and the block and chassis need to be grounded to each other to work properly. That said, it very well could be a bad starter.....I would replace the already mentioned spliced/worn wiring, and while that was being done, remove the starter and take it to an old time rebuilder for a check out. This is a 44 year old car....to be reliable, it has to be repaired/checked thoroughly....
:agree:agree:agree

When you have your starter rebuilt, put a new starter selenoid in it. Hi-torque starters are a waste of money on stock engines. Properly shim the starter. Inline tube The brake plumbing experts They sell a kit that comes with all the shims, special tool, and instructions for only $12. Lastly replace your positive and negative battery cables with ones that have twice as many copper strands in the same diameter cable. The more strands a cable has the less resistonce. You can google companies that make custom battery cables.
 

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Proper ground is CRITICAL to the correct operation of your starter! Make sure all your straps are in place. Will it guarantee a fix? ...not necessarily, but without assuring a proper ground, your electrical system doesn't have a complete circuit. I fought this for a year on my Nova and fixed it with two ground straps.
 

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:agree:agree:agree

When you have your starter rebuilt, put a new starter selenoid in it. Hi-torque starters are a waste of money on stock engines. Properly shim the starter. Inline tube The brake plumbing experts They sell a kit that comes with all the shims, special tool, and instructions for only $12. Lastly replace your positive and negative battery cables with ones that have twice as many copper strands in the same diameter cable. The more strands a cable has the less resistonce. You can google companies that make custom battery cables.
actually gm produced hi torque starters for their big block engines. they are getting hard to find. most of the cheap rebuilts floating around are the low torque variety. you can tell the difference by the length. the hi torque is about an inch longer
 

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Proper ground is CRITICAL to the correct operation of your starter! Make sure all your straps are in place. Will it guarantee a fix? ...not necessarily, but without assuring a proper ground, your electrical system doesn't have a complete circuit. I fought this for a year on my Nova and fixed it with two ground straps.
i will say it again. body ground straps have no effect on the starter. they complete the circuit for things not attached to the engine like inside the passenger compartment or lights because the body is mounted on rubber.

you could pluck the engine out of the car and sit it on the ground and it will crank over and run because it is a full circuit in itself.
 

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Still, I believe that it's best to have all factory grounds in place and in good condition. There are gauges, switches, etc. that rely on body grounds. The "cleaner" and more complete the wiring is, the better for every circuit on the car.
 

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Still, I believe that it's best to have all factory grounds in place and in good condition. There are gauges, switches, etc. that rely on body grounds. The "cleaner" and more complete the wiring is, the better for every circuit on the car.
of course it is. but for the purposes of isolating this specific problem i think its helpful to eliminate routes that wont lead to a solution.
 

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yes I drove my tempest custom gto clone 1967 about 8 mile down the interstate about 65 miles an hour ,shut it off for about an hour and wouldn't start,turned over nice but wouldn't start so I added some gas to carb and nothing so I figure its electric problem ,it sat over nite and fired rite up in the morning let it idle for a good hour shut it off starts right up now ,but im afraid of going anywhere and shuttin it off tow trucks aren't cheap,what the hell could it be,would it be a coil problem or ground wire somewhere
 

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Assuming there are no obvious issues with the wiring or the circuit for the solenoid, it's the heat soke. Try the heat shield or put on a better starter. This is common to all the V8 GM cars I've ever owned prior to about 1990. If funds are an issue, take that starter back where you got it and try for a warranty swap out.

When I bought my 67 about a year ago, that's the first thing that happened to me. Starts fine when cold...won't start when hot. New starter (shimmed correctly) did the trick and no further issues.

Good luck with it and keep those jumper cables in the trunk just in case!
 
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