79 3.5V8

My 3.5 V8 starts first time from cold every time, but after a run if it’s left for 10 minutes or so you have to keep cranking it over to start all most the point where it’s not going to have it at all. Any ideas.
Thanks
Chris

Sounds like fuel evaporation. Some carbs needed cooling to prevent this. I'm not familiar with your particular engine, does it have a heat shield fitted to the carb? Does it need one?

Col

Basics first. Does you engine have an ignition amplifier on the distributor? (A 79 model shouldn’t have, but you never know what has been done in the past). If so, then hot start problems are a sign that the amplifier is failing and needs to be replaced.

Put that to one side, if the engine starts cold OK (i.e. on choke) and not hot, then it is a sign that the mixture is too weak. Have you looked at the diaphragms in the carbs? (Take out the 4 x Phillips head screws securing the top cover and have a look). If they are damaged, that will prevent the needle lifting of the seat and giving a rich enough mixture to start. For clarity, the choke system on these puts fuel into the carbs without the use of the main jet.

I assume your carbs are top adjust, so there shouldn’t be any issues with the jet being off Centre. If they have been replaced with bottom adjust carbs, then if one or both of the jets are off Centre, they can jam the air valve and needle at low air flows and cause fuel starvation.

Next time it won’t start hot, pull out the choke and see if it starts. If it does, that will give you a hint that out is a fuel starvation issue. If it doesn’t then it is likely either an ignition issue or a carb flooding issue.

These carbs do not suffer from vaporization, provided the fuel return line is open and fuel is flowing around the loop. If not, then you will have issues.

Is it points n condenser, or electronic,,,a hot coil can cause poor starting when hot.. have you checked for a spark when hot ,the amplifier if fitted ,likes heat sink grease under it ,if its got a good spark ,then its fuel related .

It has electronic ignition, I have tried to pull the choke out but it makes no difference, i think it’s fuel related.

CRS said:

It has electronic ignition, I have tried to pull the choke out but it makes no difference, i think it’s fuel related.

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electric or manual lift pump to the carbs?

strongbers or SU ?

If it has electronic ignition, factory fitted, then almost certainly the issue is the ignition amplifier module, fixed to either the distributor on some models and mounted near the coil on others. When they go bad they do exactly as you describe.

Would a 79 two door not have had points to start with.

CRS said:

points to start with.

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HA see what u did there ...You need to check for a spark when it wont start .no sparky sparky no go goee......