E: Engine How critical are the rear cylinder oil feeds!

Nigel Spaxman

Well Known and Active Forum User
VOC Member
I have been thinking about blocking mine to get more oil going to the cams. In my engine the inlet lobe on the rear cam is the main wear problem and that is the one that shares it's oil supply with the rear piston. What I am reading here suggests it would be a good idea. There are a lot of people who have blocked those holes with no detriment. I have not read any stories ever of anyone having problems from blocking those holes.
 

Rob H

Well Known and Active Forum User
VOC Member
My next question would be............Since the rebuild, have you re-torqued the heads.

No not yet, I was waiting to get a good run in to warm the engine thoroughly. At the moment just doing short runs round the houses to sort the odd oil leak now that the flooding of the carbs has been sorted.

Any recommendations or tips on retorquing?
 

greg brillus

Well Known and Active Forum User
VOC Member
You need to back off the cylinder head bracket nuts and lock-nuts a small amount (easier to remove tank for a more easy job) I use to use a spring scale and pull with a ring/open end spanner, but now I just back off one head nut a bit and pull up firmly with an open end spanner about 10 inches long and only do one at a time. You will find they will definitely come down by up to 1/8th of a turn but usually less. Put a small black mark with a texter pen on the nut, washer, head before you re-torque, and you will see how much they come down by. Good also to nip up the pushrod tube gland nuts and check the tappets too. The reason that you back each one off a little first is so you have a "Rolling torque" rather than a dead pull from where the nut is now, this gives a much better tension on the hold down studs. Cheers..............Greg.
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Nigel Spaxman said
I have been thinking about blocking mine to get more oil going to the cams. In my engine the inlet lobe on the rear cam is the main wear problem and that is the one that shares it's oil supply with the rear piston. What I am reading here suggests it would be a good idea. There are a lot of people who have blocked those holes with no detriment. I have not read any stories ever of anyone having problems from blocking those holes.

Nigel my handsome, fit an extra pump.
Over 300k on same MK 2 cams, first 100k 5 to 10 thou worn next 200k 2 to 4 thou.So they will see me out Because I fitted a Honda oil p/p and have a constant 0.5 to 1.0 bar pressure squirting through cams onto stelited followers.
bananaman
 

Robert Watson

Well Known and Active Forum User
VOC Member
I have used just plain and very thin paper gaskets. I have never retourqued a head and not ever had a leak. One engine has about 70K miles since it was last done. What am I doing wrong?
 

Rob H

Well Known and Active Forum User
VOC Member
Checked the head nuts and some were a bit loose so tank was off and head re-tightened, hopefully thats it sorted now.
 

greg brillus

Well Known and Active Forum User
VOC Member
Even with the use of the stock thin paper base gasket, the heads will still pull down after the engine has been up to operating temperature. I would not say that Robert has done anything wrong by not re-torquing the heads, but as I served my time as a mechanic as did Bill and several others on here, we were taught to re torque cylinder heads on cars and other vehicles. It is one of the tricks of the trade that almost certainly saves the premature failure of head gaskets on at least some vehicles. It is a habit that i still use and will always use. You could carry out the practice of over-torquing the head nuts like Terry Prince does, as he pulls them down to 45 Lb's plus, his theory that once the bike/engine leaves his shop that the owners will never re-torque the heads again. I don't subscribe to that practice at all, it is a near guaranty of failure, the cylinder studs and columns through the head and the barrel are not designed to take that much load, it will either pull the threads from the crankcase, and/or damage the head. Just my views..............
 
Top