The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: Minto on 04.05. 2021 20:25

Title: Drive side con rod
Post by: Minto on 04.05. 2021 20:25
Good evening all
As I'm in the middle of rebuilding my A10 plunger lump, I've been reading loads from all sorts of places, this forum being my main source of info. Anyway, conventional and common wisdom seems to say that the oil hole on the drive side con rod should point to the flywheel or to the "inside". However, I have just come across this on Draganfly's site under the con rod listings. (Lines 11 to 12)
I'm assuming that this is incorrect as the other thing I've read is that the shell tabs should face the front of the engine, which then places the hole pointing to the inside.
Opinions welcomed
Cheers
Jase
Title: Re: Drive side con rod
Post by: trevinoz on 04.05. 2021 22:31
If you ensure that the matching numbers stamped on the rods face the rear of the engine, the oil hole will be in the right place.
Title: Re: Drive side con rod
Post by: Minto on 04.05. 2021 23:06
That was how I was intending to put it back together but found that DF instruct otherwise.
The previous owner had put the drive side rod in numbers to the back and timing side numbers forward,  *conf* seemed to work ok though.
Jase
Title: Re: Drive side con rod
Post by: Rex on 05.05. 2021 08:04
I followed the exploded diagram on Drag's old web site and assembled the crankshaft and rods with the oil hole facing outwards, then read on here that that's apparently the wrong way around.
As some pragmatist pointed out, not all con-rods even had those oils so why worry.
 All's good...so far, touch wood!
Title: Re: Drive side con rod
Post by: Swarfcut on 05.05. 2021 09:54
 Rex  Lots on the Forum already about this l'il conrod hole. It was a long running topic with detailed explanation, theory, references and experiences a couple of years ago with bergs taking a starring role.  Search "Conrod Hole" in the Entire Forum for starters. Seems Musky ran for years  with the rod the wrong way round with no apparent problem. So no need to worry too much.

 Swarfy
Title: Re: Drive side con rod
Post by: Rex on 05.05. 2021 16:28
Actually I'd forgotten all about it until I saw this thread. I rebuilt the engine over three years ago and it's done quite a few miles since then, and hopefully more to come.
According to BSA experts on the various F-B forums, I shouldn't have reused the old con-rods either but bought new ones. I guess it's easy to spend other people's money.. ;)
Title: Re: Drive side con rod
Post by: Minto on 05.05. 2021 19:23
Easy to spend other people's money? I wish it was, I've been trying to spend my wife's rather than mine on my current rebuild.
Title: Re: Drive side con rod
Post by: muskrat on 05.05. 2021 21:49
G'day Minto.
Yes Swarfy is right. The 1st time I built the plunger in 1982 there was no internet so thought the hole would be better facing out to lubricate the drive side bearing. Many hard miles over quite a few years with no problems.
The last re-build on the Cafe I used R&R rods with no hole.
Cheers
Title: Re: Drive side con rod
Post by: Truckedup on 09.05. 2021 00:41
I gave it some though and filed a small slot in the big end vertical rod face like some other engines have...