Lotus Elan

Head Oil drain modification...HELP

PostPost by: holywood3645 » Thu Apr 02, 2009 4:41 am

I have read articles about drilling out a passage way to allow better head drainage into the sump. Unfortuntly the information is not very clear and I'm afraid to mess it up.
Can anyone provide directions how to do this, pic's or sketchs would help.
Thanks
James
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PostPost by: rgh0 » Thu Apr 02, 2009 7:23 am

I have never seen anything on this so i cant help. Also never seen any need for it either so never done it. If you believe you need it then you probably have some other problem causing the excessive oil in the head that you want to drain away that should be fixed rather than focusing on draining the oil itself.

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PostPost by: CBUEB1771 » Fri Apr 03, 2009 2:13 pm

holywood3645 wrote:I have read articles about drilling out a passage way to allow better head drainage into the sump.


Later cylinder heads have a cross drilling at the back of the head to carry oil away faster from that region. Externally these are identifiable by the BSP plug on the side of the head just to the rear of the #4 exhaust port. It looks just like the plugging for the oil feed cross drilling at the front of the head. I don't think I would dare try to do this on an older head for fear of breaking into the water jacket or something else.
Russ Newton
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PostPost by: rgh0 » Fri Apr 03, 2009 10:11 pm

The cross drilling at the rear had perhaps 2 purposes.

It drained the rear of the exhaust cam which was dead end and otherwise only drained to the front of the engine. When the car was parked with the nose uphill oil would pool in the back of the exhaust cam and drain down no4 cylinder valve guide resulting in large amounts of smoke on start up. The cross drilling drains this region across to the inlet cam which is better drained by the holes as shown above that match the otherwise redundant pushrod holes in the block

It also according to the Willkins book was introducd in 1966 to enable better removal of casting sand residue from the rear of the exhaust cam which was causing problems with cam follower wear which was why the steel follower guide inserts were put in the heads from 1964.

Neither of these possible reasons would warrant trying to drill that passage in an old head today even if it was possible to do without breaking into a water jacket.

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PostPost by: twincamman » Fri Apr 03, 2009 10:55 pm

welll ---I looked at the problem and turned the oil drain rubber hose 90 degrees up so it kept the oil in the head and still vented pressure out --reason ---oil in the head keeps cams and things from wearing out --and oil will find its way back into the sump --but thats just my country look on things -- :) -ed
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