Triumph Repair: vacuum at valve cover on TR7

Question
Howard, I am still working through my engine.  
found something interesting this morning after confirming I have a good oil pump and filter.

After I replaced the oil and started the engine,  The thing ran smoothly with none of the clanking as originally described.  as it warmed however I got the sound again  NOW WHAT I FOUND TODAY WAS THAT WHEN I REMOVED THE OIL FILLER CAP ON THE VALVE COVER, THERE WAS A VACUUM AND THE ENGINE SLOWED AND WANTED TO QUIT.   WHAT COULD THAT BE A SYMTOM OF?

OTHER THING I NOTICED WHEN REMOVING THE OIL CANISTER, IT(THE OIL FILTER CANISTER )WAS ONLY HALF FULL OF OIL?

THANKS  BRUCE

Answer
Hi Bruce,

The TR-7 does have a crankcase vent system that connects to the two carburetors by a "Y" pipe and hoses to burn off crankcase fumes but it should not be forming a vacuum in the crankcase to the point that if the oil cap is off it would effect the running.

The two ports on the carburetors are on the outside of the throttle plates and pointed up at about 45 Degrees and behind the vacuum piston. There are plastic adapters on each of the two ports to adapt to the large hoses. The hoses then go to a plastic "Y" connector and then one hose goes from that "Y" to the Valve cover. This system acts as a PCV system on other cars. Later models had a pipe like a manifold to connect the two carburetors and the valve cover and the center port on one of the two charcoal canisters.

It sounds like you have crankcase hoses connected to the wrong ports.

A little oil in the filter can will siphon back but the filter can should be full if you remove the oil filter can right after running the engine.

Howard