The V8 Owners Forum -

I’m running an Edelbroke in a 3.5 rv8. It’s running nicely from cold but I’m having hot starting problems.

There’s not much headroom between the carb and the bonnet and the engine's a tight fit in my MG. Temperature is within the limits. Electric fans and holes cut around the manifolds work well.

I’ve read that it most likely a vapour lock issue but could also be ignition - possibly a bad coil.

Anyone have any ideas where to start looking or what I can test to identify the root cause?

Many thx

If it is hot, do you get a problem if you stop and immediately attempt a restart, or is it after it has sat for some time that starting becomes difficult?

If you pull a spark plug, does it spark as well if you do the same test on a cold engine?

I haven't tried looking at the plugs cold v hot. I'll take a look. If it’s weaker points to the coil then?

I get the problem immediately. As soon as the engine is turned off it won’t start.

I need to leave it 10-15 minutes or more, but it then starts as normal.

I suppose that points to fuel evaporation but I've been pointing a heat gun around the engine, coolant pipes, block, etc when hot and it doesn't seem to go above 84. I wouldn't' think that's hot enough to vaporise petrol in the fuel pipes or carb?

I guess I should look at the fuel filter. It’s just a cheap plastic and paper filter. Maybe the cheap plastic isn't heat resistant like that fuel pipes & that's the cause. I'll try looking at that when I look at the plugs tonight.

Spark plug seems to spark the same hot or cold.

I've moved the fuel filter away from the rocker cover, so will try a longer run tomorrow to see if that makes a difference.
I'll also double check the spark again.

Thanks for the pointers