Piston broke
MGB engine rebuild has begun after six long months
My Morris Minor saloon build took a back seat this month. With the shell at CBR Classic Restorations, waiting for me to have time to get stuck in with body preparation and paint under MD Andy Waters’ watchful eye, I sent the remaining panels away to be blasted back to bare steel. I also opened the tap on my bank account following the successful sale of the ‘Bean’ Mini at CCA’S PC Resto Show sale and bought a set of forged Omega pistons from MED, which were sent directly to Mike at Owslebury Crankshaft Services. With the Minor now out of sight and out of mind, I have allowed myself to concentrate on getting my MGB GT back on the road.
After melting number four piston on the A1 back in November 2018, I’ve gradually been aligning ducks. Will at the MG Owners Club’s
spares department has been especially helpful, advising me on the correct parts to purchase – from +0.040in pistons to bearings and a new oil cooler – and my mate Matt Rathbone kindly took the block and crank across to his local machine shop – Cylinder Rebores in Nuneaton – for machining. Having received a new AP clutch kit from Sam Glover that he had going spare, I sent the crank assembly down the road to
Anglian Engine Services to be balanced.
Ducks aligned
Finally, after six months, I had everything in hand to rebuild the bottom end of the five-bearing 1800 lump. I began by re-reading the full series of Theo Gillam’s B-series engine rebuild articles (PC, May 2018 to April 2019), which I kept on hand throughout the process. Despite the block being thoroughly cleaned by the machine shop, I paid particular attention to cleanliness – especially given the ‘blow-up’ that
took it off the road. Everything was cleaned in the aqueous parts washer before being blown dry with compressed air, then re-cleaned with brake cleaner and blown dry once more. I also made sure to run a small drill bit through the bore oiler holes in the bottom of each individual con-rod.
With a degree of apprehension, I shuffled off to the hydraulic press in the corner of the workshop and gently pushed out the gudgeon pins from the old pistons from each con-rod little end. Next, the new pistons went on and, finally, the fiddly task of fitting piston rings (having first checked the gaps thereof) was completed without issue.
Attack the block
Just as I began fitting the main bearings to the block, my mate Matt Rathbone arrived to lend a hand. He’s built countless A-series engines and another pair of hands – and eyes – is always a useful asset. After liberal application of assembly lubricant, we fitted the crank, thrust washers and bearing caps before torqueing each in turn – rotating the crank after each new component was tightened. Next, in went the pistons followed by the camshaft, front plate and timing chain assembly. Given that we were re-using the original camshaft, we opted to stick with the original number of shims, that we later measured and found to be bang on. Result!
With the oil pump fitted, we called it a day on tightening the final sump bolt. The short block was pretty much complete, but for distributor drive – I’m now well on my way to having an engine ready to fit. The next job is to strip and assess the head. Hopefully I’ll get away with just lapping the valves in and fitting a new set of valve stem oil seals – then I’ll reassemble it with the replacement set of valve springs that were also acquired from the Glover surplus stash.
matt.tomkins@practicalclassics.co.uk