Can't remember where this vac line goes? I have an idea just want to make sure.

 

E-types are not my speciality, but often a vacuum line that is not for the brake servo is for the heater control valve, and heater flap actuators. There is usually a little vaccum reservoir in there somewhere, at least there was on my old Series 3 XJ6, but E-types may not be as sophisticated. If it's not to the heater then I'm stumped !

 

That's a series 2 etype, it goes to a charcoal canister , a round metal can for blow by.
Early pollution control idea instead of a down pipe......
GTJOEY1314
I like willow green......

 

Ok awesome that's where I thought it went, if I don't have this hooked up will it cause the motor to rev up like a vac leak? I have the engine side plugged but not the canister

 

Short answer no, if you plug the pipe at the front of the engine the motor will build back pressure, clog up the screen and heavy blowby will push out the exhaust.
The metal canister is a charcoal filter it absorbs the smoke and fumes and underneath is a exit pipe.
So pressure doesn't build up.
The exhaust manifold heats up to turn most blowby into fumes lessening the amount of oil residue.
Good luck my friend
Gtjoey1314