to pre-fill the sludge trap or not..

[coater87]

 OK,

 Here is my quandary.

 I always use an assembly lube to put together engines. That works great, especially if its going to be a while before you start that engine. I figure I am 6 months out from actually turning it over.

 I was thinking it would be a good thing to pre-fill the sludge trap with oil while assembling. Problem with this is the assembly lube used on the rod bearings will be pretty much useless as its designed to be flushed away by engine oil.

 I have never rebuilt an engine with such a system as a sludge trap before.

 So the question is: About how long will it take to fill a completely empty sludge trap at start-up, or am I best off to fill it at assembly and hope for the best?

 Lee

[edboy]

the proceedure to prime the a10 lubrication system is to kick it over without the spark plugs in until oil returns into the oil tank. then start it up. i always thought the lube is just a 5 second gap until oil reaches the bearing surfaces when metal and friction needs a lubricant.

[duTch]

 

I have never rebuilt an engine with such a system as a sludge trap before.

 Maybe you did, but didn't know it 

So the question is: About how long will it take to fill a completely empty sludge trap at start-up, or am I best off to fill it at assembly and hope for the best?

 I filled mine, from memory it takes ~ 30ml, but was also surprised how quick oil returns to the tank by taking it for a walk in top gear with S-plugs out; and leave it at BDC so it doesn't (all ) leak out, but some may flow down from the oil tank anyway if you put at least some oil in the tank a few days out from startup  . I used some molygoop stuff that gets everywhere for assembly

[mikeb]

and leave it at BDC so it doesn't (all ) leak out

Dutch - i hadn't thought of that. are you sure its BDC not TDC? wouldn't you want the shells above the sludge trap to stop it draining? or am i getting mixed up about where the oil galleries are from the trap to the shells?
and i recall advice that molly was not great on shells -preassembly lube (thick oil) better  - tho I don't really know and am keen to learn.

EDIT: I went out to the shed and checked - yes its BDC. the oil galleries are perpendicular to the vertical line through the crank and offset slightly so that at BDC the holes (on each side of the big end) are higher/more central than if at TDC. so if at BDC the sludge trap would retain most of any oil in it, as it would be below the galleries to the shells. assuming your crank is the same as the LJ one i looked at. good tip Dutch

[coater87]

 Maybe you did, but didn't know it 

  Boy, would that be terrible. But no, I would not have missed it.

 For assembly I use stuff made by Torco, works very well.

 I am not certain about watching the oil return guarantees the big ends are being lubricated on first start, too me that just means oil is being returned from the sump no matter where that oil came from?

 I guess my concern is that the oil has a ways to go before it even gets to the crank, then it has to to fill the sludge trap before you have actual pressure there for the mains. I figured pre-oiling the sludge trap would cut some of the time out of this. But on the other hand, its going to do a lot of draining in 6 months, at least enough to flush the assembly lube out. Personally, I would rather have assembly lube there than oil at start up.

 I figure before I put the barrels on I would pour enough oil in the case to get some in the cam trough, and a little in the sump to help prime the return and get a little fling going.

 Maybe im just seeing problems where there are none. But while installing the sludge tube it struck me how large of an empty cavity that really is.

 Lee

[duTch]

 

  I am not certain about watching the oil return guarantees the big ends are being lubricated on first start, too me that just means oil is being returned from the sump no matter where that oil came from?

Granted; and given some others recent issues regarding priming PRV and such I should have acknowledged that.

 As I said, I think I estimated about 30cc in the big end gallery, but I guess it's a
conundrum you'll have to decide betwixt swings and roundabouts

 You can get as much oil as you like in the cam trough and sump by pouring it down the rocker inspection holes, that way you can wet the valves too-  just don't wet-sump it*eek*

[BSA_54A10]

You are over thinking .
These bike were designed to be rebuilt on mums kitchen table while she was down the shops.
By modern standards the clearences are of grand canyon magnitude.
As the boys said, a few kicks without the engine turned on will do the trick .
A little assembly lube if it worries you.

At the factory the oil holes got a squirt of oil before the rods went on and that was it.
There is a video of the BSA factory tour which shows A 10's being assembled.
A lot rougher than most would believe.