Practical Classics (UK)
Rebel engine gets an unanticipated rebuild…
It was all going so well… the new bespoke aluminium tailgate catch, the final part of the jigsaw, arrived from Harding Auto Services the day before the off, and the Rebel was looking ready for action. But it wasn’t to be. If you read last month’s Team Adventure, you’ll know that the Rebel with a Cause was retired from PC’S Britain’s Favourite Classic Charity run early with engine troubles. Danny had reported sluggish running and noisy clacking tappets, so workshop guru
Clive Jefferson had set to work on the basics – setting the tappets, cleaning silt from the carburettor that had been sucked through in the car’s time on the road and fitting a new electronic distributor, coil and HT leads from Accuspark.
Immediately the engine sounded more sprightly, so with time of the essence, it was loaded onto a trailer and delivered to the following day's start point. But once warmed up, disaster. The tappet noise had been masking a grumble from the bottom end and the oil light began to flicker at idle. The car was going nowhere apart from back to the workshop after its photo call.
Back at PC HQ, Clive and Matt soon had the engine out of the car and on the bench. As the oil drained out, all that glittered certainly was not gold. With the sump whipped off, Matt removed the crank to reveal an extraordinary amount of scoring on all journals and the bearings down to bare copper. The liners were damaged too, and the oil pump full of glittery abrasive sludge. It was clear that nothing short of a complete rebuild was in order… I asked Matt to bring the engine over to my Wisbech workshop where he and I could spend the day getting to the bottom of what happened and rebuild the engine from the ground up.
The engine was the one part of the car that we hadn’t touched, it having been rebuilt when the project came to the PC workshop back in 2020, so stripping it was a voyage of discovery. No smoking gun to the cause of the catastrophe, but myriad small problems that, together, we suspected, had led to the disaster we had experienced. The bottom rings of two of the pistons were damaged, for example, from clumsy fitting, the thrust muff (stop giggling at the back) for the distributor shaft was upside down and so on.
I keep a huge range of Reliant parts in stock for my business, CHG Classics, and having supported the project from its inception am dedicated to seeing it through. As such, I decided to donate everything that would be required to put the engine back together again. New liners, a set of New Old Stock pistons and rings, a mint secondhand crankshaft,
‘With the mains torqued up, the crank refused to turn’
NOS bearings, an OE quality oil pump, gaskets, bushes and much more besides. If this car is to achieve top dollar for NHS charities come sale time, it’s got to be perfect. So if you’re considering putting in a bid, please dig deep!
The crank was out and the block thoroughly cleaned when Matt arrived, so we started our day by knocking out the old liners before selecting a fresh set of piston rings, gapping them in the new liners, fitting them to the pistons and sliding each piston and ‘rod into their new liners, lubricated with plenty of fresh 20w50. Next, just as the factory did it, we coated the bottom of the liners with a bead of sealant and installed them in the block, tapped them ‘home' and fitted the cylinder head with a NOS head gasket from the stores to clamp them in position and allow the sealant to set. Then, with the block inverted, we fitted a fresh set of main and big end bearing lower halves, coated them liberally with assembly lube and dropped in a mint, polished, standard size crankshaft. Matt used plastigauge to check the bearing clearance (bang on) before we could fit and torque the main bearing caps for the last time… we hoped.
With the mains torqued up, the crank refused to turn. Cue half an hour of mild panic and careful engineering assessment. Had we found our smoking gun? The upshot of what we found is that the mains needed very, very carefully, gradually and diametrically tightening until the correct torque was achieved. At that point, the crank spun freely. Problem solved. Sigh of relief all round and finally the big ends could be torqued up – and the crank turned freely.
No end float in sight
The camshaft was next, again with plenty of lubricant, before the distributor drive was fitted (through a new bush as the original was badly scored) followed by its thrust muff – the correct way up this time. On went the timing chain and cover, followed by the front pulley. One last turn of the engine on the front pulley nut to check all was well… the crank was locked.
It transpired that it was the tightening of the front pulley nut this time that was causing the problem – compressing the thrust washers which required adjusting. Apart it came once more, and the back face of the thrust washers were carefully sanded back and a trial and error approach taken to ensuring that the correct end float, as measured with a DTI, was achieved. At the time of writing the engine is still in my workshop for a couple of final jobs, including fitting a Helicoil to one of the head threads that pulled out when torquing the head down (it’s been one of those jobs…) but by the time you read this it should be back under the bonnet of the Rebel and running sweetly.