Morris Minor
Matt finally starts to assemble his Minor’s new engine
It’s been an incredibly long time coming, but finally I’ve taken the plunge and assembled the bottom end of the Minor’s new engine. I took the decision to build the engine in my shed at home – it meant I could lay everything out across a workbench without it getting in the way of other activities while I meticulously cleaned, listed, checked and bought each component – but first I had to straighten and reinforce the shed, move in and install a workbench, make safe the existing wiring with an RCD and install lighting then sort tool storage.
I cleaned and painted every component in the weeks leading up to E-day, carefully tracing around gaskets and checking everything I could think of for size – including the conversion spigot bush for the Type 9 gearbox that required reaming out to fit onto the first motion shaft.
I’m glad I checked! This done, I laid out the vast number of parts required, invited friend and seasoned engine builder Matt Rathbone over to play and prepared to begin.
Get it together
After a thorough clean, I removed the freshly line-bored main bearing caps, screwed in ARP competition studs, dropped in the +0.010 main bearings and installed the crankshaft, before refitting the main bearing caps with ARP nuts with a drop of their ‘ultra torque’ assembly lube on each. I’ve gone for a full set of ARP fasteners for mains, big ends, flywheel, head and manifold studs, to ensure that the correct clamp load for each component is not only reached, but maintained. This small investment at this stage gives peace of mind and prevents potential failure due to a stretched or broken fastener. Next, it was time for the pistons, which is where we hit a stumbling block.
I’d ordered bearings for a Midget,
but was using an A+ crank and con-rods with larger journals. A quick phone call and mercy dash to MED in Nuneaton later, we had the correct bearings in hand.
We fitted the piston rings and lubricated the bores with engine oil. Installation was made easy thanks to the tapered piston installation tool I’d splashed out on while at MED. Then, into the inverted block, went eight brand spanking new black phosphate-coated Piper cam followers, smothered liberally with their ‘Driven’ engine assembly lubricant. It’s essential to use new followers and plenty of cam lube to prevent premature wear to the camshaft during the ‘breaking in’ process. Again, after a thorough clean and with the 1/8in BSPT gas plug thread-locked into the front drilling, in went the Piper METSC1 camshaft with plenty of lube on all 16 lobes as well as the bearing races. Then it was the turn of the oil pick-up followed closely by the sump.
Time after time
On went the front plate, then it was the slightly scary bit – installing the Vernier timing chain.
The camshaft’s spec gives us a timing angle of 108 degrees when measured at the rocker.
Mini engine expert Keith Calver’s technical guide advises that timing measured at the pushrod will be 2-3 degrees retarded from that at the rocker. As such, we aimed for a figure of 106 degrees.
We fitted the timing chain as any other, then ascertained TDC using a dial gauge mounted a 360-degree protractor, zeroed to a pointer wire from the dynamo adjuster bolt. Then we dropped in the second pushrod along – inlet 1 – and relocated the dial gauge to the top of this. We then turned the engine until the pushrod (and by extension the top of the cam) was at its highest point, turned the engine anti clockwise 25 degrees on the dial gauge, then clockwise back to 10. We took a reading from the protractor here, then continued to turn the crank clockwise until the dial gauge returned to 10. Again, we noted this figure. We added the two together then divided by two to give the cam’s timed angle. Slackening the bolts of the Vernier timing gear and inserting a screwdriver into the back of the cam allowed us to tweak the cam angle which we then locked then re-checked until a figure of 105.5 was eventually reached.
I’ll double check the valve timing at the rocker when the head, currently still away for machining, is back. It’s having unleaded seats, phosphor bronze guides and big, stainless steel valves fitted. Having got as far as we could have hoped, we wrapped the short block in cling film and called it a day. Hopefully it won’t be long before I get to hear it roar in the car.