[ImperialCrown]

Sounds fuel system related. The carburetor may be flooding or rich. If you hold the accelerator part way down on a hot start, does it start easier?
The choke may be used first start in the morning, but should be wide open on a hot-start.

 

[KOG]

Can also be lean burn ignition which is notoriously flaky. You need to check for spark before going any further.

 

[daddysgirl]

We checked and there is no spark

We have changed all plugs, wires, rotor and had it timed with a light, ran fine before this, only thing i can think is maybe its out of time now... Will that cause no spark when it is hot?

It also has an electronic spark control , on the air filter, that is for vacume advance on the distributer. Could this be to fault?

 

[ImperialCrown]

No spark when warm? You can try to chill various underhood ignition components one at a time until spark returns and the car starts.
Aerosol 'freeze' or other rapidly evaporating spray can be used. Avoid contact with skin or eyes.
Concentrate on the distributor pick up coil, inside the spark (lean burn) computer housing,etc. until you find the culprit.

Edit: If you do use spray inside the distributor, make sure that it is a non-flammable aerosol. An ohmmeter, if you have one would be safer to measure the pick up with.

 

[Bob Lincoln]

Sometimes an ignition coil will fail open when warm and make contact when it cools.

 

[KOG]

The device on the air cleaner is the Lean Burn computer. Best way to fix one of those is to convert it back to earlier electronic ignition which involves replacing distributor.

 

[chuzz]

Does it have a control module on the firewall? If so, it could be defective. You can have them tested at Autozone if you can find a COMPETENT counter man that knows what he's doing. This is what I'm referring to. Of course, this is without the lean burn engine.
http://www.autozone....omString=search

 

[KOG]

79 is all lean burn. Controller on Air cleaner is lean burn. And the distributor will have no vacuum advance unit for lean burn.