Hitchcocks Forum

Hi every one I have been for some time stripping my engine down for a big end job. After going on here for advice I have found it is invaluable, I found advice on the crank pin bearings and lots more. today I striped down the head and rockers' I am glad I checked the oil ways because as suggested on this site they was chocker block with big end debris I a lucky the top end did not seize up on its last run. The oil pump was also clogged with fillings. so please folks those who are thinking of doing a big end job don't take any chances clean every nook and cranny in the engine and if you see any fillings in your oil don't leave it to long.

THANK YOU ALL FOR YOUR PAST HELP AND ADVICE

Terry

Terry, that sneaky white metal in the rockers could easily slip past if you weren't looking for it in there

Just a thought (and an idle question): how efficient is the filter at catching swarf? I would have thought with a combination of a dry sump design and a full flow filter, quite efficient is the answer, yet big ends do seem to distribute swarf through the motor when they give up...just curious.

Cheers
TimG

Tim,
No filter on the scavenge side, oil is sucked straight from the sump and fed to the rockers so anything in the sump will get stuck inside the rockers

There should be a strainer before the return pump. This is where I found larger big-end flakes. My 1942 WDCO has strainers before the feed and return pumps, just like my 2001 Bullet.

Chris,
There is a strainer on the scavenge but the whitemetal goes through it, sure some will get caught but by that time it is too late anyway because the bearing is finished

Another question I am confused about the big end bushes in the work shop manual it don't show two bushes but in the parts list on the host site it shows floating and fixed bushes which one makes contact to the crank pin the one with the holes in or the one without the holes. witch one would we call the shell on any other engine.

When you have split the crank case and have the crankshft out proceed no further on your own. Use a competent engine building shop for them to split the crank. Wait until the engineer has checked the big end, he will tell you what parts to order.

As Bryan says, Unless you are a very competent engineer and have the required equipment to realign the crankshaft.

Hi Terry. I suppose you could call the Floating Bush the Shells. The floating bush (The white metal covered, radially perforated bush) is the equivalent of all the rollers that run around the crank pin in a normal roller type big end. In effect the oil on both sides acts as the sliding surface and the bush separates the two surfaces. It is covered in white metal, which is quite soft, just like a normal plain bush shell. The white metal is able to absorb microscopic debris and also allows the oil to microscopicall penetrate its surface to help lubricate the bearing. Being softer than the crank-pin or conrod big-end journal, it keeps most of the inevitable wear localised on the replaceable shell or bush rather than damage the journal or big end pin and also the con rod steel journal. As parts are not too expensive most owners get all the parts replaced with new items, and many owners now opt for the Alpha Roller bearing instead of the bush bearing.