Help Won't turn over when warm.

This is driving me nuts.

I've got a stock rebuilt 1967 400 in my Bonneville,  She cranks easily and starts well when cold, but once it warms up the starter absolutely refuses to spin the motor (it tries but no) . I believe the compression was lowered when it was rebuilt, as there is no knock/ping at all on regular gasoline, so I don't believe this is a high compression issue.

I've rebuilt the carb, replaced plugs, wires, cap, rotor, battery, cables, reset the timing and tried several stock style starters, and just can't cure this issue.

Does anyone have any suggestions for what I might be overlooking?

I do have a stock points/condenser style distributor to swap in, the current unit was converted to electronic points at some point but I'm not sure how this would keep the motor from turning when warm. I've checked and get 12 volts at the coil when cranking and 8 or 9 while running so the resistor wire has not been removed.

Any help would be much appreciated, I would really like to drive the car more often.

More info, factory style stock single exhaust system, with the cross over just in front of the starter.

I suppose if I had to I could add a high torque starter, but there are hundreds of these cars starting every day with the stock starter, I feel like I must be over looking something.  

Do you have an aftermarket Temperature Gauge installed? How hot is the motor? Is it at normal operating temperature? Or getting really hot?

Check the battery.....it might have the voltage but a dead cell. I would check the load and amperage first. Could be that.

Next have the alternator tested...a faulty alternator will definitely keep you from starting happened to me multiple times in various cars. The car not starting when hot is a noodle scratcher.

The car is simple mechanics....i overlooked the simplicity of them for two years and my car wouldn't start bc of a combo of burned points and a bad starter. I know right?

Good luck should be pretty simple.  
"It's too close for missles Goose I'm switching to guns!"

Greg

I THINK THE CRANKING AMPS SHOULD BE AROUND 200. I HAD THIS PROBLEM WITH A 69 GTO . SOMEBODY HOOKED THE WRONG WIRE TO THE TEMP SENDING UNIT. WOULD SHORT OUT WHEN HOT.

WHAT IS THE CCA OF YOU'R BATT, WHAT SIZE BATT CABLES COPPER OR ALUM WIRE.

YOU CAN TRY PULLING THE COIL WIRE IF THE STARTER CRANKS YOU HAVE TO MUCH TIMING FOR REG GAS.BACK THE TIMING UP TILL IT CRANKS. 10 TO 12 DEG WITH VAC ADV UNHOOKED. THE TIMING SHOULD NOT CHANGE WHEN THE ADV HOSE IS HOOKED UP AT IDLE. IF IT DOSE YOU HAVE THE WRONG PORT ON THE CARB. THAT WON'T EFECT THE STARTING.
YOU'R HARMONIC BALANCER MAY HAVE SLIPED.IF IT HAS YOU WON'T BE ABLE TO SET THE TIMING BY LIGHT.

YOU MIGHT TRY A HEAT SHIELD I USE HEADER WRAP OR A JEGS GEAR REDUCTION STARTER. GOOD LUCK AND DON'T GIVE UP.  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD

It sounds like the classic hot starter problem. I had the same problem and used a high torque mini starter no more problems !  

My vote is for ROWSLEY. Bad balancer, screwing with the timing readings. Sounds like the initial timing is cranked too far ahead.  

with a HAND HELD volt meter....

set it to 20 volts DC...   touch one wire to the Negative battery post...  one wire to the engine block...  have somebody crank the engine while is hard to crank.. what kind of voltage is displayed..  should be less than 1.0 volts while cranking... if you get more than 1.0 volts.. then you have a ground issue...

on the positive side of the starter motor.. do you know if the alternator is hooked up directly to the starter top post as it is on many GM cars...

then touch the positive battery post and the alternator output terminal... attempt to start the engine... do you get less what 1.0 volt DC while cranking.. or attempting to crank..  you should..

the proper way to perform this test is positive battery to the top post on the starter with the volt meter while cranking.. again.. less than 1.0 volt DC is expected..

if you get more.. then you have a connection issue.. or a wire size that is too thin for the load.. or the starter motor has an issue and is drawing too much amperage... that does happen..  

I had the same problem, try advancing your timing it might help, I ended up with installing a mini starter, and advancing timing, no future problems.  

It sounds like your timing is advanced too much I agree. are you using the Full vac port or the timed vac port?
Is your balancer original? Cause I think Rowsley has something there about the balancer, One thing you have a conversion kit in the distributor?
Which one? Because I understand you need to have 12v on some of the units the resistor wire will not give it enough power to work correctly. I just went through this with a points to electronic conversion.  

Really can't tell much about the points conversion. It was done prior to me purchasing the car.   That's one reason that I've been considering using the old points style distributor from my parts car.   I do have 12 volts during the start cycle though so I'm doubtful that low voltage start is the issue.  

I think you need to look into it, If it's a pertronix unit, you will need 12v at the distributor or the low volts will kill the unit, the others MSD and Accel I am not sure about, I'm finding out anything is possible with an engine.
It was suggested to check your timing, could be too far advance?  

Most likely in the starting system, battery, bad battery cables, bad ground.
You can disconnect the power to the ignition system and eliminate that right off the bat.  

mb68bird:
Most likely in the starting system, battery, bad battery cables, bad ground.
You can disconnect the power to the ignition system and eliminate that right off the bat.

m68 bird is correct.

disconnect ignition system when this is effecting you ...

if it cranks normally at that point.. then sometime in the ignition... if it does not crank well with the ignition coil disconnected.. then its the starting system..



as a side point... can you remove the distributer cap...  grab the rotor... twist it..  does it twist a fraction of a turn. then snap back to the hard stop...  1/32 of a turn..

when the mechanical advance parts on the distributer shaft get old.. the grease dries up.. gets rusty.. seizes.. prevents the mechanical advance from retracting hot.. makes hot starting an issue as it has too much advance..

you might also want to examine the advance weights under the rotor.. that they are not worn.. the stubs are not worn.. the springs are intact...  that the pertronix shutter wheel that is under the rotor is not causing something to hang up..

only take the rotor off if it fails to snap back to the stop on its own...  

I'm with Jack on this one. Had the same issue. start fine when cold and hard turing over when hot. If you haven't already done so, try installing a heat shield on the starter.. Similar to the one the factory  installed.  
Jim,

how many miles do you have on the motor? get the motor hot, pull the coil wire and see if it will turn over. if it dose back the timing off till it will start. if it won't the motor may be a little tight run it easy till it brakes in.

just how hot is the water temp?
hat size batt? i use at lease 1000 cranking amp.
what size cables? i use 2-0 copper welding cable. and always used a stock starter.  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD

I know it has at least 2000+ miles on the motor, I bought in in north east Canada, and drove it home to Phoenix, AZ.   Then on weekends it would get a 50 mile workout to and from the Pavilion car show.