'48 LS Engine rebuild

[fffcycles]

Hello Folks,

Now that I found a new cam for this from Feked, gasket set from Draganfly and the correct bushes from Baxter's I have started on the engine assembly this morning. I have some questions on a few things and would appreciate some guidance on a couple of points.
Got the rivets I needed and replaced the gearbox oil seal, no problem; but is there no drive side oil seal on the crankshaft ? All my Nortons have them and many others I have done, though not the Ariels, so need to confirm this one.
For this age of machine I understand the castellated nuts with split pins but since the PO put this together I will open these up and check shells and clearance again. Any tips on the crank shells and experience with the split pins?
Frank

[trevinoz]

No seal on the crankshaft, Frank. Just a slinger between the bearing outer race and the case.

[Swarfcut]

Frank, All engines before 1953 Model Year do not have a crank oilseal.

  These engines have an oil slinger outboard of the main bearing, clamped against the inner race by the cush drive sleeve. it's a simple flat washer with a pressed edge Part 67 349 listed as a bearing shim. Offer into the bare case before fitting the bearing (early ball race type) or the outer race used in the later demountable roller bearing type design. These bearings are different sizes and do not interchange.

   The drive sleeve on these pre-oilseal early engines is a close fit to the crankcase, and most have a scroll cut onto the outer edge, others are reported to be plain. Trev nailed it that bit quicker.

    All is detailed in Service Sheet 208, here the A7 references are mainly for your early engine, which confuses owners of the later redesigned versions of the A7 & A10. Service Sheet 207 details crankshaft journal dimensions which are the same for all small journal split conrod type cranks.

  WARNING!!!!  No if's or buts, the crank needs the blanking plugs removed and the narrow oilway between the big end journals cleared out, this so called sludge trap really needs a clinical standard excavation. This is a known weakness in drive side big end lubrication, obstruction of oil flow here is the cause of many catastrophic  engine failures.  Big end bolts for this Longstroke engine are unique and  not readily obtainable, so preserve them if you can.

 Most aspects of assembly are the same as for the later engine, all have been featured on the Forum and it is a matter of having a good dig into previous posts.

 Swarfy.

[fffcycles]

Hello Swarfcut,
Got out my bulletins looked up some of the details and testing crankshaft end float today.
I always clean out sludge traps on all engines I rebuild and this one was plugged on the gear side really badly. Explains why the PO had to weld up the case from a thrown rod but all is good now.
Frank

[fffcycles]

It is always the way of rebuilds to go sideways I say. Had the sludge plugs removed by welding on 1/2"nuts, torqued them out with an impact gun, cleaned up everything then went to install new LS plugs I had ordered but these are too small it would appear. I have ordered a set of the large plugs but have to wonder why these holes/plugs are different (7/8" ?) than that listed in the parts catalog. Another week or so transit for the latest order from Drags, Oh Well, better get on with the '68 Thunderbolt or Trident clutch while I wait.
Frank

[Swarfcut]

 Frank.  Reckoning all small journal cranks have the same plugs, just measured a 1949 L/S (steel rods) plug. Its the same as the later  small journal alloy rod crank type, plug is part 65 615, same plug both sides.

  Searching the L/S parts list on the Forum Literature section, can't find a plug listed for the L/S crank. Having said that, the early parts books are an all in one format, so not easy to navigate.

 So, another conundrum that no one could have seen coming.  Evidence of previous attempts to remove the plugs, wrecking the threads and an oversize plug to suit? Who knows?

 Swarfy.

[fffcycles]

Thanks Swarfy,
I did find 65 615 in the parts catalog listed as “crank complete” so something wrong in that. Also looked at what I had ordered and Feked had it marked as 0615 and my presumption this might be correct has led me astray? I have ordered the hex type and a pair of straight slot type for this next try and will see what fits in correctly.
Frank

[Swarfcut]

 Frank  Feked list 65 615 Crankshaft Oil Hole Grub Screw as 5/8"/ 16mm, I've measured the crank thread ID at 15mm so that's the one for my small journal L/S crank. Crank Oilway Plug is what it is.

 Part 67 615 is indeed a complete crank listed just 3 lines above in my parts book.

    The larger 7/8" plug is used on the later big journal cranks, A10 and A50/A65. Big Journal plugs are somewhat different. One has a locating tit for the sludge tube, other plug is plain.  All Alloy Rod A7 cranks use the same smaller plug as do small journal A10.  I assumed you had ordered correctly supplied plugs that did not fit because the holes in the crank web were not as expected.

 Thread size for the smaller  plugs is 5/8" X 20 TPI. Use the search bar above, look under "Sludge trap plugs" in the Entire Forum, tells all.

 Swarfy.

[fffcycles]

Mystery to me how this has come about but the 5/8" plug was too small so ordered 7/8" plugs but as these are 11 tpi won't fit the 20 tpi(?) thread in the crank. Having a bit of a time measuring the tpi but it seems the crank has either been modified or built up with different parts. I will search through my Triumph bits from the last motor I did and see if the Triumph plug will fit. Certainly hope I find the right plug as this is the only thing holding me back.
Frank

[fffcycles]

Gentlemen,
Working away at the A7 engine rebuild and waiting for what I expect will now be the correct sludge trap plugs and meanwhile turned up what might be a spare crank in the boxes for bits that came with this motorcycle. I have a few pics here to show what puzzles me about what I have for cranks. Second two pics are the crank that came out of the engine last two are the crank from the bits I got and first photo is the two together. First crank has shorter splines for cush drive bearing and 7/8" sludge trap plug, suspecting this might be the wrong crank I have been assuming was correct and second crank has longer splines for the cush drive bearing,  5/8" sludge trap plugs (one is driven too far) along with a stamping on the crank R010 (needs a good clean before I can get proper readings but might have been reground??). Any bits of wisdom will be greatly appreciated and will continue to look using the search tool but nothing definitive yet.
Frank
ps At least I have the R.E. insured and ready for a ride while waiting.

[Swarfcut]

 Frank. The crank for the Longstroke engine is wearing the ball race on the drive side. Other characters to note.....

   Extra widening of the flywheel adjacent to the webs, looks like bit extra added each side extending  round almost half of the rim. The mystery crank certainly has this feature, but is lacking the  usual Flat Bottomed Cut Out on the flywheel periphery between  the big end journals.

 These features  together are only found on the Longstroke crank.

 Drive side shaft measures 98mm web cheek to end of  cush nut thread. Splines extend to the thread, there is no plain area as on the mystery shaft.

 Drive side bearing size and type differs from later model A7/A10

 Other bushes and bearings are the same as later small journal cranks, fitted with split cap alloy rods. Longstroke steel rods with split caps use the same big end bearing shells as the small journal later engines.

 

 Swarfy.

[fffcycles]

Thanks Swarfcut,
Finally found a picture of the long stroke crankshaft on Mike's site and it looks like the spare one I have. Now to clean it up measure everything and confirm if I have the correct shells for the connecting rods. The one that was in the engine "as assembled" looks awfully close and the rods fit well but I suspect is from an alternator(?) version of the A7 engine with the clear area on the shaft but will keep on looking until I figure it all out. At least I have the correct sludge trap plugs now so I can clean that up and will get ahead with this one as weather is allowing some riding, above 15C today, so I can get this one out on the road soon.
Frank

[fffcycles]

Well, sludge trap plugs came out pretty good and someone has been there already. Real plus the bearing surfaces were clean and well greased R010 stamped on the flywheel must be 10 thou under as measurement with decent calipers is 1.448 vs 1.46, need to get out my decent measuring tools to be certain, so where do I go for 0.010 under shells?? Draganfly only list to 5 thou for 67-0226 but I will search some more as it appears 67-0320 at -0.010  might be suitable.
Existing crank that was in there reads 1.419 and con rods have correct shells for that dimension so have to dig through the boxes some more to see what else is hid in there.
Frank

[fffcycles]

Cleaning the supposedly correct crank and found one of the bearings has no second oil passage. If this is what came out of this engine then no wonder it threw a rod !!! Off to my good friends at Speed Valley shop for a little remedial machining will be next.
Frank

[RDfella]

Seeing as BSA were concerned the timing side didn't rob all the oil from the drive side (hence the drilled rod) maybe that was intentional?