The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: SixFingerJack on 24.05. 2011 20:38

Title: Holy bushes Batman!
Post by: SixFingerJack on 24.05. 2011 20:38
First of many queations.
I just got some new small end bushes for my '48 A7 and when I examined them, they were lacking any oil holes.
The old ones have two holes drilled in them that match up with a slot cut into the conrod. See Below.
(http://img15.imageshack.us/img15/2056/conrod2.th.jpg) (http://img15.imageshack.us/i/conrod2.jpg/)
(http://img215.imageshack.us/img215/9917/conrod1.th.jpg) (http://img215.imageshack.us/i/conrod1.jpg/)
Apart from that they are identical.
Have I got the wrong bushes?
Is it ok to drill the new ones?
Thanks in advance.
Title: Re: Holy bushes Batman!
Post by: muskrat on 24.05. 2011 20:55
G'day Jack,
               drill'em, don't leave any burrs. Freeze bush and heat rod (150 C), should just drop in.
Cheers
Title: Re: Holy bushes Batman!
Post by: SixFingerJack on 24.05. 2011 21:17
Thanks mate, will do.
Title: Re: Holy bushes Batman!
Post by: muskrat on 24.05. 2011 21:54
Forgot to say drill after fitting to rods, a lot easier than lining up holes with a hot rod in one hand and a freezing bush in the other.
That sounds a bit kinky  *eek*.
Cheers
Title: Re: Holy bushes Batman!
Post by: Goldy on 24.05. 2011 22:35
I know cerainly on other BSA models that holes are not drilled but a slot is cut across the bush when in situ using a hacksaw or thin file.
Title: Re: Holy bushes Batman!
Post by: beezalex on 27.05. 2011 16:30
The procedure is to press out the old bushes, press in new, drill oil holes and then ream/hone to give .001" clearance to the wrist pin.  I prefer honing but you can rig up a jig to make the holes square with a reamer.