Aside from a zillion technical questions, the most popular start to any conversation about power units tends to concern the cost. That could be a cylinder head, engine, gearbox or the whole unit, reconditioned to standard spec, full race or something in between. It’s also a question that is difficult to answer accurately as the amount of work needed depends on the state of the parts supplied. As such I don’t have a build price list for anything other than modified cylinder heads – that’s easy because they are all done to a specific recipe using the same processes and parts each time. Looking through the ads in the mag, there are companies that offer engine and gearbox builds at set prices, so I guess they must use the same principle as I do for the heads – a set recipe for machining, parts and labour that they duplicate. But there is nothing to cater for the enthusiast who is considering having a go themselves, so just wants to know the essentials that will likely need replacing and an idea of total component and engineering costs. In response I thought I’d oblige and do a breakdown of a very basic engine and gearbox rebuild, covering the engine this month, cylinder head next month and gearbox after that. This should help achieve two goals; one is a list of the basic parts and engineering tasks that are likely to be needed with an idea on cost, the second is a list to work to in order to price up to anywhere you want to. Though there are cheaper components out there, I have steered clear of them and stuck to good quality recognised brands. Realistically, you won’t know what needs doing/replacing until you have stripped the unit down and thoroughly inspected everything. Anything you are not sure on, either ask your local engineering shop to take a look (though it has to be remembered that it is likely to want to sell you as much as it can) or consult somebody from your local Mini club. I have simply started with the most basic of lists from the majority of units that have been through my hands. For instance, some low-mileage, well-serviced and cared-for engines may have piston to bore clearances within the necessary tolerance, so need no more than a hone and re-ring. The crankshaft bearings may even be in good enough condition to be used again following careful inspection.
BLOCK
After any machining work carried out on the block, it is absolutely essential the engine is cleaned inside and out prior to reassembly. To do this you will need to remove the oil gallery plugs and coolant jacket core plugs. This is pretty straightforward with the later ‘cap’ type plugs, but a little more difficult on the earlier solid brass plugs in the oil gallery ends. If in doubt, get an engineering company to remove them for you. Most automotive engineering shops have a parts washer that they run all engine components through after machining. The best way to ensure the oil galleries are clean and clear of debris is to use special radial type brushes, available from the likes of Frost Restoration along with contact or brake cleaner and compressed air. Cam bearings regularly crop up in conversations on engine rebuilds – should you change them or not? As they are nigh-on impossible to change correctly without special tools, if they are only very slightly scored I would leave well alone.
After any machining work carried out on the block, it is absolutely essential the engine is cleaned inside and out prior to reassembly. To do this you will need to remove the oil gallery plugs and coolant jacket core plugs. This is pretty straightforward with the later ‘cap’ type plugs, but a little more difficult on the earlier solid brass plugs in the oil gallery ends. If in doubt, get an engineering company to remove them for you. Most automotive engineering shops have a parts washer that they run all engine components through after machining. The best way to ensure the oil galleries are clean and clear of debris is to use special radial type brushes, available from the likes of Frost Restoration along with contact or brake cleaner and compressed air. Cam bearings regularly crop up in conversations on engine rebuilds – should you change them or not? As they are nigh-on impossible to change correctly without special tools, if they are only very slightly scored I would leave well alone.
BORES AND PISTONSBefore getting the block re-bored, make sure you can get pistons to fit. It may sound obvious but I have heard several stories of folks getting a block bored then finding they can’t get the pistons. You need to make sure the new pistons are the same compression height as the ones you are replacing to avoid issues on reassembly with the pistons sticking out the top of the block. The easiest way to check is to push the wrist pin from the new piston into the pin bore of the old one and compare the crown heights. Compression ratio also needs to be considered. Pistons with bigger dishes in them than the ones being replaced will lower the compression ratio, so dull the engine’s performance. Pin-to-crown height and dish capacity details are generally available in catalogues at engine reconditioners/engineers or from Mini/ASeries specialists.
CRANKSHAFT
Take the crankshaft along to whoever you choose to carry out the machine work on your rebuild and get them to check it over. Journals need checking for size, roundness and taper. If there are any scores or signs or wear in the journal surfaces, get it reground. I have my cranks reground regardless as the process also takes out any slight bending that may have occurred in use from when it was new. It also allows for consistent sizing of the journals and stroke correction.
Take the crankshaft along to whoever you choose to carry out the machine work on your rebuild and get them to check it over. Journals need checking for size, roundness and taper. If there are any scores or signs or wear in the journal surfaces, get it reground. I have my cranks reground regardless as the process also takes out any slight bending that may have occurred in use from when it was new. It also allows for consistent sizing of the journals and stroke correction.
CRANKSHAFT BEARINGS
If the crank turns out to be in perfect condition, not requiring a grind, I would strongly recommend fitting new bearings anyway, even if those that came out looked fine – there is bound to be some wear there after thousands of miles of use. Before deciding to go with the existing bearings, I would strongly recommend using Plasti-gauge to check the journal to-bearing clearances. If the crank needs a regrind, you will need over-size bearings anyway. You need two sets of bearings – one for the main journals that run in the block, and one set for the big end journals where the rods fit to the crank. Material-wise, as standard they are steel-backed aluminium (bi-metal) type bearings. These bearings are very wear resistant, so have a very hard facing on them. The issue here is that if any small particles make it past the filter, they tend to gouge the crank journal rather thanor as well as the bearing facing. I always use competition spec lead/indium (tri-metal) bearings in everything I build as they have a softer facing that will absorb small particles without damaging the crank.
CENTRE MAIN THRUST WASHERS
The copper-coloured faces of the thrust washers allow the crank to rotate easily while you have the clutch engaged. They must be fitted with the copper-coloured face towards the crankshaft thrust faces, away from their block seats. Many have got this incorrect and ended up trashing the crank, thrust washers, and on occasions the block as well. They are put under load every time the clutch pedal is depressed, so need to be in good condition. If there are any signs of scoring or uneven wear, replace them. Go for standard size initially; you will need to check the crank end float when re-building the engine.
CON ROD BOLTS
The small-bore rod bolts seem to be pretty reliable even when reused a couple of times, so no need to replace them. The large bore rod bolts, however, have a bit of a chequered history. I know there are hundreds of folk that have probably reused them without any issues. I have seen way too many fail, even on standard rebuilt engines. Consequently I would strongly advise fitting new rod bolts and nuts for peace of mind.
The small-bore rod bolts seem to be pretty reliable even when reused a couple of times, so no need to replace them. The large bore rod bolts, however, have a bit of a chequered history. I know there are hundreds of folk that have probably reused them without any issues. I have seen way too many fail, even on standard rebuilt engines. Consequently I would strongly advise fitting new rod bolts and nuts for peace of mind.
CAMSHAFTIf the cam shows signs of wear, such as pitting near the peak of the lobes or misshapen flanks either side of the peaks, then it will need replacing. You could take the opportunity to replace it with a sportier cam to give the engine a little more power. You will also need at the very least some good quality anti-scuffing paste or proper cam assembly lube – essential to protect the cam lobes and followers during the break-in period of a newly-assembled engine.
CAM FOLLOWERS
The cam followers should have smooth, shiny faces where they run against the cam lobe. The sides will also have a band around them, top and bottom, shined up due to the follower rocking, rotating and rising and falling. The faces may show rings radiating out from the centre of the follower. These are normal, known as ‘sombrero-ing’, caused by the follower rotating. If the faces are pitted in any way or look like they are flaking/breaking up, they will need replacing. This applies even if the camshaft looks to be in mint condition.
The cam followers should have smooth, shiny faces where they run against the cam lobe. The sides will also have a band around them, top and bottom, shined up due to the follower rocking, rotating and rising and falling. The faces may show rings radiating out from the centre of the follower. These are normal, known as ‘sombrero-ing’, caused by the follower rotating. If the faces are pitted in any way or look like they are flaking/breaking up, they will need replacing. This applies even if the camshaft looks to be in mint condition.
CAM DRIVE COMPONENTS
The vast majority of standard engines you are likely to come across these days will be equipped with a shoe-type timing chain tensioner and single row (Simplex) timing chain, instigated in the late 1970s. Earlier engines just used a single row chain, some with ‘tensioner rings’ that were simply nitrile rubber rings placed either side of the cam gear teeth that the chain would cushion against. As a bare minimum replace the chain and tensioner pad. The factory-fitted sintered steel gears are actually pretty tough and do not wear much at all, so rarely need replacing. Even so a whole chain and gears kit is not that expensive. Many take the opportunity to fit a dual row (Duplex) chain cam drive kit in the belief that the chain is substantially stronger and therefore longer lasting before chain stretch becomes an issue. However, there are some very cheap and cheerful kits on the market using extremely cheap chains that stretch badly within several hundred miles of use. For the vast majority of standard and even modified road engines, the Simplex set-up with tensioner is more than adequate. That’s providing a decent quality chain is used. OIL PUMP The oil pump sees the oil it is feeding to the rest of the engine before it passes through the oil filter. It therefore also gets to see any detritus hanging about in the oil, and consequently is prone to damage. It is surprising how much damage the oil pump can sustain and still provide an adequate stream of oil to the engine. I would strongly advise you fit a new oil pump unless it is unquestionably in excellent health with no marks in the rotor and annulus faces.
The vast majority of standard engines you are likely to come across these days will be equipped with a shoe-type timing chain tensioner and single row (Simplex) timing chain, instigated in the late 1970s. Earlier engines just used a single row chain, some with ‘tensioner rings’ that were simply nitrile rubber rings placed either side of the cam gear teeth that the chain would cushion against. As a bare minimum replace the chain and tensioner pad. The factory-fitted sintered steel gears are actually pretty tough and do not wear much at all, so rarely need replacing. Even so a whole chain and gears kit is not that expensive. Many take the opportunity to fit a dual row (Duplex) chain cam drive kit in the belief that the chain is substantially stronger and therefore longer lasting before chain stretch becomes an issue. However, there are some very cheap and cheerful kits on the market using extremely cheap chains that stretch badly within several hundred miles of use. For the vast majority of standard and even modified road engines, the Simplex set-up with tensioner is more than adequate. That’s providing a decent quality chain is used. OIL PUMP The oil pump sees the oil it is feeding to the rest of the engine before it passes through the oil filter. It therefore also gets to see any detritus hanging about in the oil, and consequently is prone to damage. It is surprising how much damage the oil pump can sustain and still provide an adequate stream of oil to the engine. I would strongly advise you fit a new oil pump unless it is unquestionably in excellent health with no marks in the rotor and annulus faces.
OIL GALLERY PLUGS 2.90 5.80
COOLANT JACKET PLUG 3.00 3.75
(CAM BEARINGS) (10.50) (11.58)
PISTON SET 188.50 149.96
CON ROD BOLT (AND NUT) SET (48.80) 42.32
(CAM ON NEW BLANK) (160.00) (160.00)
(RE-PROFILED CAM) (110.00) (110.00)
(CAM FOLLOWER SET) (16.00) (16.00)
CRANK MAIN BEARINGS: RETICULAR TIN 20.22 20.22
(CRANK MAIN BEARINGS: COMPETITION) (37.50) (28.50)
CRANK BIG END BEARINGS: RETICULAR TIN 18.50 18.50
(CRANK BIG END BEARINGS: COMPETITION) (33.00) (31.50)
(CENTRE MAIN THRUST WASHERS) (7.83) (7.13)
OIL PUMP 13.19 13.19
IWIS STANDARD SIMPLEX CHAIN 16.20 16.20
(IWIS BIG-PIN SIMPLEX CHAIN) (29.25) (29.25)
TENSIONER PAD 5.44 5.44
(SIMPLEX CHAIN/GEAR KIT) (19.01) (19.01)
(DUPLEX CHAIN/GEAR KIT) (23.00) (23.00)
(DUPLEX CHAIN, IWIS TOP GRADE) (29.25) (29.25)
ENGINE GASKET SET 10.89 9.21
PRIMARY GEAR OIL SEAL 3.50 3.50
TOTAL COST £282.34 £288.09
ENGINEERING PRICE LIST
BORE/HONE BLOCK 88.00
FACE BLOCK 45.00
CRANKSHAFT REGRIND 70.00
(FIT NEW CAM BEARINGS) (25.00)
TOTAL COST £203.00
SUNDRIES
ENGINE CLEANING BRUSH SET 10.00
BRAKE CLEANER – 4 LITRES 18.00
ENGINE ASSEMBLY LUBE 7.52
CAM ASSEMBLY LUBE 4.13
ENGINE OIL – 5 LITRES 21.50
TOTAL COST £61.15
COOLANT JACKET PLUG 3.00 3.75
(CAM BEARINGS) (10.50) (11.58)
PISTON SET 188.50 149.96
CON ROD BOLT (AND NUT) SET (48.80) 42.32
(CAM ON NEW BLANK) (160.00) (160.00)
(RE-PROFILED CAM) (110.00) (110.00)
(CAM FOLLOWER SET) (16.00) (16.00)
CRANK MAIN BEARINGS: RETICULAR TIN 20.22 20.22
(CRANK MAIN BEARINGS: COMPETITION) (37.50) (28.50)
CRANK BIG END BEARINGS: RETICULAR TIN 18.50 18.50
(CRANK BIG END BEARINGS: COMPETITION) (33.00) (31.50)
(CENTRE MAIN THRUST WASHERS) (7.83) (7.13)
OIL PUMP 13.19 13.19
IWIS STANDARD SIMPLEX CHAIN 16.20 16.20
(IWIS BIG-PIN SIMPLEX CHAIN) (29.25) (29.25)
TENSIONER PAD 5.44 5.44
(SIMPLEX CHAIN/GEAR KIT) (19.01) (19.01)
(DUPLEX CHAIN/GEAR KIT) (23.00) (23.00)
(DUPLEX CHAIN, IWIS TOP GRADE) (29.25) (29.25)
ENGINE GASKET SET 10.89 9.21
PRIMARY GEAR OIL SEAL 3.50 3.50
TOTAL COST £282.34 £288.09
ENGINEERING PRICE LIST
BORE/HONE BLOCK 88.00
FACE BLOCK 45.00
CRANKSHAFT REGRIND 70.00
(FIT NEW CAM BEARINGS) (25.00)
TOTAL COST £203.00
SUNDRIES
ENGINE CLEANING BRUSH SET 10.00
BRAKE CLEANER – 4 LITRES 18.00
ENGINE ASSEMBLY LUBE 7.52
CAM ASSEMBLY LUBE 4.13
ENGINE OIL – 5 LITRES 21.50
TOTAL COST £61.15
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