By Peter Jacobsen
Chapman Report - Aug 1984

A proverbial problem with the Twin Cam engine is with the oil pick up. Any driver that hasn't experienced loss of oil pressure on right hand turns isn't trying hard enough. A number of solutions are available, ranging from dry sumps to improved baffling. The engine builder can improve the oil pickup by making it easier for the oil to return to the sump. The exhaust side of the head does not have any drainage to the sump other than at the front, and hence a large amount of oil can accumulate there. On most castings I have seen, the drainage way is very rough. Some time spent cleaning this up will be fruitful.

Some engine builders paint the inside of the block with Rust-Oleum. The idea here is to provide a smooth surface so that the oil quickly returns to the sump instead of coating the interior walls.

In a related matter, while compiling the technical manual, I noticed a Lotus Facotry Service Bulletin which Kiyoshi had a copy of. The bulletin dealt with oil consumption, but I was particularly interested in a paragraph that talked about the "omission" of a breather hole in the head, between the cam shaft chamber and the breather box chamber. I have owned four different Lotus heads, only one had this hole (the bulletin is dated 1 Sept, 1969). Since breathing problems plague this engine, the modification looks like a good idea. The factory recommends a 7/16" hole! The factory says that this hole can be drilled with the head in situ, but I can't condone this. Anyway, the details are in the technical manual, but here is the text from the bulletin.

Omission of the 0.4375 inch breather hole which passes from the camshaft chamber situated between inlet ports 3 and 4, upsets the breathing characteristics of the engine and the camshaft cover should be removed to check this point. Omission of the breather hole is often indicated by heavy oil deposits in the air box.