The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Klaus on 08.09. 2015 08:57
-
Hi gents, does anybody know the diameter with toleances of the bore from a big journal conrod? I mean the bore without the shells.
Hayns tell the figures for conneting rod big-end eye diameter 1.4610 - 1.4615 inch. But it is for small journal.
cheers Klaus
-
I think the answer is here:
https://groups.yahoo.com/neo/groups/bsa/conversations/topics/13582
BSA service sheet No. 207, October 1948, re-printed May 1955.
Engine nos. XA7 - 101 to 600; first re-grind 1.4600 to 1.4595, with a
0.065/0.060 face radius both sides. No second re-grind.
Engine nos. XA7 601 upwards and A10 models; three re-grind possibilities.
1.4495 to 1.4500; then 1.4400 to 1.4395; then 1.4300 to 1.4295.
More information from that service sheet; Note that certain engines will be
found to have the left-hand connecting rod drilled to improve lubrication
......
BSA service sheet No. 207, October 1948, revised January 1958.
As above, but also data for the large journal crankshaft;
1.677/1.6765 with 0.120/0.115 face radius; 1.667/1.6665; and 1.657/1.6565
(10, 20 & 30 thou undersizes).
-
I don't think that's correct, going on those engine numbers for starters, and unless I'm reading it wrong they're small journal regrind sizes anyway...I'm fairly sure I have that noted somewhere, give me ten minutes or so...
I mean the bore without the shells.
edit- Ten minutes or so later...can't find the exact info just now, but measured a couple of old rods and they're in the vicinity of 1.8425"...notebook'll be in the last place I left it.
I bought new rods and have the specs on them somewhere too.