I had been working at the garage for a couple of weeks, at the tender age of 16 in 1974, when I asked Tom Butler if there was anything I could do to MYT one evening after work, 'can you polish them until you see your face in them' pointing to the brake drums on the car, I said yes, so I was shown how to remove the wheels & then the Alfin brake drums & I polished them until I could see my face in them !  - what an introduction !

I started work on the engine a few months later with being allowed to lap in the valves, then i was allowed to assemble the heads, we used 79001 Production DB3S cams then, with turned down DB4 valves (very oversize for the head), the head was ported before I started working on the engine.
We used to set the valve clearance's at 0.010" inlet & 0.015" exhaust 
with STD original 'mush material' buckets (cam followers) then, with STD valve springs. 
The cam timing was set with a modified cam template (based on an original AM template), a 1/8" metal plate which lay on the head with 2 cam lobe shaped cut outs at the 'correct' timing, really accurate, not !, it worked though as it was an AML way of doing things.
I used to get better results from the engines than anyone else or perhaps, being the apprentice, I was cheaper than anyone else ! I'll stick to the 1st explanation.

It had awful downdraught Weber carburettors from a DB3 with a twisted inlet manifold, the carbs were then at 90° to the engine, the carb trumpets were so close to the bonnet that there was no paint on the inside above the trumpets, there were very small holes at the bottom of the inlet manifold or a small slot on the manifold face to let any puddled fuel out when you turned the engine off, Jack was the only person who could set these up, bloody things, they are now missing (2011). 
The other thing was because they had different length tracts they used to burn out pistons, they needed different jets on the outside to the inside (2011 thoughts).HP - about 165 / 170 bhp
It had a 3ltr engine then, with STD pistons, rods, VB6J crank, flywheel, coil sprung clutch, STD gearbox, 4.09:axle, dual circuit Alfin drum brakes, Mk111 wheels, it also had a extra wiper switch that Jack had fitted when the 2 speed wiper motor was fitted, so you could select one of the 2 speeds but only turn them on from the original switch.
It still has that wiper motor & the switch.

We then tried having our own 84mm (works 3S size) pistons made by the man (a Mr Pearson who also made an overhead cam Mini head in alloy off his own back) who had a workshop on the car park of The Wilsons Arms in Knowle.

We've just found one of those pistons attached to a small bit of conrod, looking at it now (2011) it was a mess, the dome was a lot larger than STD or even 3S, they weighed a lot more than STD cast pistons, the gudgeon pin wasn't tapered in the bore so even that was heavy.
They were also just cast using a pattern & then turned, not barrel turned though.
End result was the compression was too high, the engine pinked even on 5 star fuel & the pinking blew holes in the crown & if it didn't pink the STD connecting rod's broke ! 
The head gaskets failed with regularity, with hindsight it was the STD bored out liners flexed & caused the failures.
AML may also have found this out because they used 84mm for a time & then went back to 83mm on the DB3S until the RB6 all alloy engine arrived.

Years later in 2012,  I don't think we ever had more than 190bhp from 3 ltrs & 205 from 2.6ltrs - we spent more time on the 2.6 than the 3 ltr, now we have easily 30% more with 3ltr and regularly see 200bhp from road car engines.
 
Further engine developments are planned for the car when it is returned to roadworthiness in 2013, with a 2.6 ltr engine planned giving over 220 bhp (make that 265bhp from 2649cc's after another recent major development session building an engine with almost that power output, August 2015)         


 

all images & text on this site belong to the Webmaster of this site
© 2010