Lotus Elan and Lotus Elan Plus 2 Forums

So, after a year of working on this engine I finally noticed this morning-having bolted the head to the block-that the hole for the breather, in the underside of the head, has been properly blanked off with a frost plug-and it was done a long time ago! The valve cover has breathers added on the top and there is a breather outlet where the fuel pump would normally bolt (electric pump). This is an old racing car. The block is not the original-that was badly cracked and was disposed of by the machine shop (sob!).

What is the general consensus-do I knock out the frost plug and install the rubber connector or?

Yes, I'd think so and also put a blanking plate where the fuel pump lived.

Is the breather air hole also blocked or is that still or will be in use?

The oil tube is just a oil drain from the oil separator built into the head for the standard crankcase breather. If you're not using the breather, there is not going to be much air flow through the separator and therefore not much oil to drain and no need to have the tube. Just another place to age and leak oil.

I decided to leave the engine as it has apparently been for the past fifty years-without the rubber connector. There is a breather on the plate over the fuel pump hole and additional breathers in the valve cover. For anyone else who would like to do this, a 20mm frost plug fits the hole above the fuel pump position very nicely. I don't recall what was in the original block.

On the Ford engine from which the twin-cam Cylinder blocks are 'borrowed', the hole above the fuel pump IS THE BREATHER. It has an external oil liquefier/catcher.

Bill, my engine has three other breathers fitted-four if I count the blanked off hole at the front of the cam cover. I think it will breath ok