moorepower

Cletus, you could be right. Im not that clued up on these motors and these are the first mods I've done to it.

There is a 3/8 hose which runs from the bottom of the carb to a brass tee, which has a 1/4" transmission vacuum and a 3/8" hose which runs to a fitting into top of the block behind the distributor. I only assumed it was a PCV.

What difference would a draft tube make?

Could this be causing excessive crank case pressure to blow the breather cap off the filler tube.

Could the increase in air flow from a 2 barrel to 4 barrel cause more blow by if the rings are slightly worn? (Which they could be. Im unsure on the history of the motor as its a recent Nevada import)

Hi guys, 

I've got a '61 impala with an internally stock 283. Recently I replaced my stock 2 barrel and manifold with an Edelbrock performer manifold and 500CFM carb. The result is fantastic and the engine is much more responsive.

One issue is when I took it for a blast down the motorway the breather cap on the oil fill tube came off. Luckily it ended up inside the engine bay. When I stopped I bent the two prongs out on it and put it back in its spot. On the way home, it came off again and this time I lost it for good.

My understanding is that the air gets sucked through this tube, down through crankcase and is sucked up through the PCV valve and into the carb, with the fumes getting burnt in the combustion process.

Im not sure if the viabration has sent it loose or if there is a build up in crank case pressure?

How do I test the PCV valve is operating?

BTW ive got stock script valve covers without any breathers on them. 

Has anyone had similar issues?

Cheers

Luke

Name: Luke Moore
Location: Auckland
Cars you own: '61 Impala 
Mods to them (can be brief or detailed): Edelbrock manifold and Carb, HEI dizzy, Air ride
How you found out about oldschool: Browsing the net