620 Vapor Lock Fuel Issues

[DavetheDatsun]

My '73 620 appears to be having issues starting up again after running in the heat for a long period time. Does anybody have any issues with vapor lock?

[spanner]

I have the same problem - same truck as yours.
I think it's fuel evaporating in the carb due to heat
Takes a few seconds of cranking to get fuel, then it starts.
It's annoying but I don't see there's a cure unless we move to Siberia.

[DavetheDatsun]

Ha that's funny. Yeah I am not sure if there is a good solution. I am going to play around with a few different things and see if I can figure something out.

[Charlie69]

Start by wrapping steel fuel line with rubber fuel that runs along bottom of valve cover on carb side of the intake manifold.
Are you running the stock Hitachi Carb?
Are your intake and exhaust manifolds bolted (married) together? If they are there is a heatshield that should be between the carb and intake manifold. You can easily make a heat shield by tracing an carb base gasket.

[DavetheDatsun]

I've rebuilt the carb and swapped it out for a Webber and it runs great now. I was running the stock Hitachi but now run the Webber. I also went through and changed the ignition points and that helped as well.