Blow off valve?

[Harry]

I've recently bought another series 1 Bighorn.Exc cond,factory flares and very tidy interior.Con rod through the sump so very good price.I'm building up a motor using parts of that motor and my old swb motor.The new one is intercooled and while removing the inlet manifold found what appears to be a blow off or overpressure valve bolted to it.The outlet is teed into the rocker cover breather hose.Does the valve need to be there?It doesn't exist on the non intercooled motor.I've blanked the hole off because I don't want to lose any boost.I've also removed the egr pipe and valves and blanked those holes.When it's up and running it'll be getting the dyno treatment.Also,anyone got any info on lpg injection?
Thanx,Harry.

[James W]

It's part of the crankcase ventilation system via the rocker. It may have been removed if it was faulty.

Any blow off valve on a diesel would be nothing but a joke with the inlet always wide open there is nothing to "blow off".

[Harry]

I'VE removed it.Idon't see how it can be part of the crankcase vent system.I't's sprung closed against the inlet manifold.I think it's more an overpressure valve for the egr system.Mine hadn't done anything for a long time,it was full of crud.