'55 Square Four engine strip.

[Roger Gwynn]

Ideally a milling machine or similar, set the case on the bed, timing side face down, clock up on the drive side bearing outer race, remove d/side case and bore bush to size. That's how it is done at Drags, there are other ways but depends on the equipment available.

[nevhunter]

If the mill is not dead accurate you'll get an error that way. There's a long distance between those bearings if the spindle is NOT at right angles to the bed both ways. 90 degrees apart. Worth checking it first. I've usually done BSA twins by machining the Bushes before inserting it in the case. nev

[paul.jameson]

The Draganfly method is one used by many competent engineering shops.

Nev's method of turning to size before fitting is one option outlined in Waller - but in the section on the KH (which uses the same bearing). The trick with this option is to turn them to a size such that after fitting, with contraction of the crankcase, they end up the correct size.

My method involves a reamer with a sleeve round its shaft which fits in the roller bearing inner to align the reamer.

Whichever method you use, this is a relatively skilled operation and will rely upon having a micrometer and bore gauges available. A vernier caliper will not be sufficiently accurate for this job. My advice would be to have someone competent such as Drags or South Cerney Engineering do the job for you if you have any doubts at all about your capabilities for it. If you want to talk through the operation with me, you can always give me a ring on the number given in Cheval before making up your mind.

[nevhunter]

The kingpin type adjustable reamer with it's extended arbour works OK but one that size is worth a bit. Whitemetal (babbit lined) bearings need a close working fit as they fail prematurely if there's play that allows hammering. A very thin layer is far better than a thick one . The BACKING is just mild steel tinned to hold the babbit. A loose fit there also lowers oil pressure and reduces the amount that gets to the big ends. Nev

[john.davies]

Another option if you decide to get it done professionally is T & L Engineering near Bedford so not to far from you. I got them to do my bottom end for me include fitting the bushes as they have good experience with SQ4's. They did a wonderful job and quickly too.

[tomwalker]

Thank you John, I have heard of them, and will give them a ring next week.

[tomwalker]

I have dis-assembled and cleaned my engine, and am now measuring and checking.
I dont seem to have "Oil seal washer" part number K147-53
I am hoping you could explain what it does, and if it is missing, is it a problem?

[allan.walker]

(deleted)

[paul.jameson]

K147-53 is something of a mystery to me. This is not the oil seal itself, but a thin steel washer which goes on one side of it. The only conclusion I have ever been able to reach as to its purpose is to "tighten up" the oil seal. They are cheap enough and available from Drags or if I remember correctly Imay well have a spare one on the shelf.
K147-53 suggests a part originally for the KH but I can't find it in any of my KH parts books and I can't think where you would fit it on the KH. Hmmm.

[allan.walker]

My mistake, sorry!