Yes, boring into the main block saddles on an A-series can be the death of the
engine as the timing gear and timing chain tension is non-adjustable and is
based on the crankshaft always sitting in the same position (not moving up or
down). Usually they would mill the flat surface of the caps, mount them up
and bore into them with the cutting tool just touching the bottom of the block
saddle, but not removing any material from the block side.
Head was done by Selby and Sons a few years ago (ported, matched and opened up
for larger valves and rocker pads re-shaped). This round started with first
gear going out last summer so I pulled it apart to fix that. I have an
original early S 3 synchro gearbox and I quickly discovered that to find the
parts to rebuild my box was going to cost exponentially more (assuming I could
find all of the parts in the first place) than upgrading to a newer 4 synchro
box. I bought a good used former Minimania-built 4 synchro remote change box
and did some modifications to be able to make it the same ratios (using the
same replacement gears) as the original S box.
I then lightened the flywheel and pressure plate and did some modifications to
flatten the diaphragm spring, which will put less wear and tear on the clutch
and crank thrust washers. I sent that assembly to Seven Enterprises who did
the balancing last month.
Up until this point I still wasn't planning on touching the motor because the
previous owner in Australia said that he had rebuilt it shortly before I
bought it. That was in 2002 though. It ran fine, but smoked a little when
cold, and there were signs when I had it opened up that it might not have been
rebuilt to a very high standard if a all, and even though the bearings were in
very good shape, I thought it would be risky to be this far into it and then
put it back together without going the rest of the way. This way I will have
a base line where I know it was rebuilt by me fresh on x/xx/xx date. I did a
light hone of the cylinders, new rings, main and rod bearings as well as the
work Seven is going to do. I also lightened and balanced the rod caps per a
Mini performance manual I have to smooth out the idle and reduce rotating
mass.
The rest of my gearbox parts just landed in the US from England and the big
brown truck should deliver those on Monday.
Cheers,
Craig
> Date: Thu, 17 Feb 2011 16:00:54 -0800
> From: gtwincams@gmail.com
> To: nobbc@autox.team.net
> Subject: Re: [Nobbc] Machine shop
>
> Cool. Glad Liam suggested Seven Ent., ,as I had forgotten about them.
>
> It's often good to avoid honing main saddles and caps if possible, based
> on many comments to me by machinists, because cumulative removal of
> material can affect bearing fit. However, the benefit of honing is that
> it doesn't shift the crankshaft axis up into the block, because unlike
> line-boring, honing does not entail removal of height first, then boring
> to back to round.
>
> What else are you doing to the motor? Head, pistons, etc.
>
> Cheers,
>
> Greg Tatarian
>
>
> On 2/17/2011 2:38 PM, cmurphy68@hotmail.com wrote:
> > Thanks for the replies. I spoke to jerry at JNW and got a quote for the
work, and also at Seven Enterprises in Auburn. Seven had a lower quote, even
accounting for shipping both ways (over 100# with block, crank for sizing,
pistons and rods). Jack at Seven said they can usually avoid having to hone
the crank saddles and caps but would check them for free with the other work
being done. Also included surfacing the block, which I didn't ask JNW to
quote, but it could use it. Since Seven is a Mini specialist, it seems like an
easy decision. Good to know about JNW for future local machining needs
though!
> > Sent via BlackBerry by AT&T
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