oil filler cap

[Phantom]

G'day all , as playing around with the oil cap on the rocker cover , and when the car is running i can barely get it off because of the suction from the motor, is this normal? The motor is a worked 202 , yella terra head 350 Holley etc, do i need to get one of those little chromed caps with a filter?
                                          Cheers Rusty
                              

[Jockster]

Rusty
 In Holdens with Positive Crankcase Ventilation, the later red motors and blue and black motors had a non-vented oil filler cap and a small hose from the rocker cover to the air filter, which allowed filtered air to be drawn through the crankcase. The earlier red motors did not have provision for this air cleaner hose and used a vented cap (the chrome cap with the filter as you put it), if you are using the early type rocker cover you will need a vented cap.
Cheers
Jockster

[Phantom]

I have a hose from the rocker cover to the manifold , the rocker cover that came off the 202 (i reused mine off the 186) has three holes in it What is the third hole for? A hose to the carby?


                               Cheers Rusty

[Glenn 'Stinky' Stankevicius]

I had the same problem as you did Rusty, I went out and got a vented oil cap. I wasn't about to swap over the Thomas alloy cover.

[Jockster]

Rusty
The hose from the manifold to the PCV Valve mounted at the rear of the rocker cover provides vacuum in the crankcase to draw any crankcase fumes back into the combustion chambers through the manifold. To work it has to be able to draw fresh air in. As you are using a 186 Rocker Cover you need the vented cap, on the 202 cover  the third hole is for the hose that goes to the air cleaner. So buy a vented cap and your problem is solved.
Cheers
Jock

[Phantom]

Cheers Jock ,
                          Rusty