Fitting an 1800cc Engine
By Neil Cairns

Look for diagrams sometime in future.

This is now a very popular option, and there are three ways of doing it, first, pay somebody else to do the work or buy a ready modified engine from a specialist (in the M.G. market) or Do It Yourself.

In the DIY option, which this article is all about, you still have various choices. By far the easiest way is to find a THREE MAIN BEARING ex-MGB engine, with an engine number prefix 186 or 18GA. These are usually gold plated and as rare as hens teeth, and now in great demand for those restoring early MGB's that fetch figures over f10,000 once restored.  Why use one of these 18G or 18GA engines?  Well, they fit simply straight onto the normal BMC gearbox that yours and my Farina has fitted.   No modifications are needed, other than using a Riley or M.G. Farina exhaust manifold, its a bolt up job.  If you are determined to find one of these early 196264 MGB engines, buy M.G. Enthusiasts Magazine, and get hold of copies of Enjoying MG. from the MGOC, and Safety Fast magazine from the MGCC; engines do appear every now and then. The biggest problem with this unit is its THREE main bearings, that are BIGGER than our 1622cc ones, and shell bearings are almost non-existant, and the engine is prone to break crankshafts if hammered.  The gearbox used on these early MGB's sometimes had an overdive fined, yes it will fit into a Farina, IF you cut bits out of the transmission tunnel, AND you modifythe prop-shatt to a four bolt fixing at the gearbox end. This gearbox suffersthe same problems as ours, (it IS our 3 synchromesh unit,) so your present one is good enough. The next DIY option is to use the later MGB engine, with five main bearings, of which the most common is the 1IVunit,(yes, there was an 18 GB,GC,GD,GE,GF, & GK, and these are all 5 main bearing units, with odd differences for the American, (Californian) market, mostly over the breather system.) To use an MGB 18V unit reauires a lot of work and you will need to fight off other MGB owners, though these 18V units often appear in the above M.G. press for sale. These 5 main bearing MGB's use a completely different 4 syncromesh gearbox, that is much bigger than ours.

The 18V engine also appears in the Morris Marina 1800 single, and twin carb, saloon car, as well as the Sherpa van. In these applications they have a CAST crankshaft, where as the MGB version has a forged one. Buy now though, with exchange recon cranks about, there is a right mixture of differing metal specification crankshafts fitted to both MGB's and Marinas. For our purposes, it does not matter, unless you want to supercharge/turbocharge your A60. Both Marinas and Sherpa vans still appear inscrap yards, or for sale cheap. The Sherpa version has a low compression, but if you are going to recondition it, using MGB/Marina 1800TC pistons will restore the compression ratio to 8.9 to 1, quite O.K. for todays leadfree petrol: (If you are to restore an engine, as well worth having hardend valve seats fitted so you can use Leadfree.)  On ALL 'B' Series engines, it is the 'dish' in the piston that controls the compression ratio.

Onto the really involved stuff now, as most of you will opt to buy a Marina/Sherpa/late MGB 18V engine to fit into your pride and joy.  If you look at the 1622 engine under your bonnet, a I6AMW or a 16AA ( 16RA, 16GE, or 16GF, if an M.G. or Riley,) or a 48G if a Goldseal recon-unit, if will look almost identical to the 18V engine you have purchased, and now sits on the garage floor. Do not be fooled, the engine mountings, whole bottom end, sump, valves, pistons, flywheel, flywheel bolts spacing, clutch, and spiggot bearing differ.....  all there to cause you grief. (The 16AA & 16GF engine had updated bits fitted to it from the 1800 range, such as the sump, and water pump.) The ex-MGB engine will have front mountings very similar to your 1622 unit, which a spanner can very quicly cure by swapping bits over. BUT the 18V Marina/Sherpa unit has its mountings on the sides, so the front engine plate needs to be taken off your 1622, and fitted to the front of the Marina/Sherpa block.  Look at picture l, an exploded 1800 18V unit, and picture 2, our 1622 engine.  Note how the front engine plates, items 11 and 28 respectively, differ. Your old one has the engine mountings lugs on. Its a simple bolt up swap, but I would advise you to use YOUR 1622 sprockets and NEW chain, timing cover, chain tensioner. However, you MUST use the big heavy 18V fan belt pulley, (picture No l item 15,) as it is a vibration damper. It will make your dynamoe over-speed, so now is the time to fit an alternator, ( or a bigger pulley on your dynamoe.) The 1800 cylinder block has odd lumps and bumps on it, the 1622 engine mounting brackets you bolt on to the 1622 front plate will hit one of them. Simply grind awaythe bracket to clear it.

The best bit about the 1622 to 1800 conversion is, that really you only use the bits from each end of your 1622cc engine, as the whole centre section, comprising the block,sump, head, water pump, is not disturbed. The only faults you may find are the water outlet elbow may need swapping as some 1800 ones face the wrongway, and the downwards facing throw-away cannister oil filter will hit your steering column, only seen on some MGB engines. If you have senous problems with the oil filter on the 1800 fouling things, use the one off me 1622 engine alongwith its pipe, but its a shame to lose the throw away filter.

On the opposite side tothatoil filter, are the two tappet covers on the cylinder block, (pictures No3 for 1622, and No 4 for 1800.)I personally remove the 1800 ones and fit the plain 1622 ones, AND use the 1622 rocker cover. This makes life easy as you retain the old breather system to your normal air filter. However, if you are to use the1800's carbs, (orjust the 1800 Marina single carb,) leave on the 1800 covers, and run the breather pipe to the connection on the carb body.

Picture No3 also shows the 1622 rear plate and picture No5 the 1800 rear plate and flywheel. No6 shows the 1622 flywheel. Nowthe serious problems start. You need to use the 1622 engine rear plate on the 1800 engines block, so the gearbox will mate up. You can either bolt the 1800 rear plate to the 1622 rear plate, (obviously OFF the engines.................) and drill the 1800 one to suit the 1622 gearbox mounting holes, BUT this causes serious problems with the starter motor alignment fouling of our chassis. It is far easier to have the centre of the 1622 rear plate machined to take the rear oil seal of the 1800's. Our ancient 1622 engine has a very crude 'scroll' oil seal, where as the 1800 has a nice efficient neoprene lip-seal, on the post 18GB 5 main bearing engines,( picture Nol item 47.) Unfortunately, our 1622 rear plate also has an oil drain ground into it, on the engine block side, that if you do not have braised up, will allow oil to pour out of the rear main bearing. It needs BRAZING up, not welding. The plate is a casting and welding will cause metal fatigue and cracking. The brazed up gap needs filing flat accurately, as it will need to fit up against the gasket. See picture No. 3. Take both 1800 and 1622 bits with you to the machinist, so he can see what you want, and it will give him measurements from the originals.

With the 1622 plate now bolted to the 1800 block (all the holes are the same, no drilling needed) the flywheel from the 1800 HAS to be fined, because the 6 bolt holes are further appart than the 1622 one, so you CANNOT use your old flywheel.  You will have to use your 1622 clutch, so this means more engineering where the holes have to be drilled, doweled, and tapped ACCURATELY for correct balance, in to the 1800 flywheel. Once done, bolt on the 1622 clutch cover to the 1800 flywheel, using your 1622 clutch driven plate, so it will fit onto the Farina gearbox. Use your 1622 starter motor, the 1800 preengaged one will foulthe 1800 distributor fitted to the 1622 rear plate.

Alas, we are still not finished.  There are various sizes of sintered bronze spiggot bush in 1800 crankshafts, the bit in the hole where the gearbox shaft goes. You need to fit a 5/8th" internal diameter one. (I actually found that the old 1622 one went inside the 1800 one!) Now you discover that the engine and gearbox simply will not pull up close together. This is because the gearbox shaft on your 1622 gearbox, is TOO LONG.  It needs about 314" cuttmg off, but as its hardend steel, it actually needs grinding off.........or you can drill 3/4" futher into the rear of the 1800 crankshaft and break through into the rear main bearing oil way.............yes, it has been done before!!

So, by now you have used your 1622 front plate and engine mountings, on your 1800 cylinder block, sump, head and water pump. You used your 1622 timing gear, (not compulsory, but lots of Marina engines only have a single chain to save costs, ours uses a stronger duplex chain) with the 1800 vibration damper fan pulley,( use your 1622 bolt/starting handle dog.) You used the correct side covers to suit your carb and vent system, ( either all 1622 or all 1800.) You usedyour 1622 rocker cover if you kept your carb and vent system, orthe 1800 rocker cover if using the 1800 carb and vent system. (The 1800 has no vent pipe.) You MUST use the correct oil filler cap, this tiny item will cause havoc withthe mixture strength if you use the 1622 cap on an 1800 rocker cover, that has a crankcase vent into the carb body. The 1800 oil filler cap has a filter as part of it, and a inwards vent under the cap edge.  (You have to be very careful with enclosed crankcase breathing systems................) You have fined the right oil filter that misses your steering column. You have removed the Marina/ Sherpa engine mountings. And you have spent money on machining the rear 1622 engine plate to take the oil lip seal of the 1800, as well as brazing up the old 1622 oil drain slot, and having the 1800 flywheel drilled and tapped to accurately take the 1622 clutch and plate, and fitted a 5is" spiggot bush and removed about 3/4" from the gearbox first motion shaft.

Quite an easy modification really. But we still have not finished. The Marina/Sherpa/MGB manifolding is no good alas. The exhausts all face WWN, picture 7, where as our 1622 Farina faces rearwards, picture 8 and 9. This severely limits our choices of inlets. Most opt to use their old 1622 inlet and exhaust system. The main problem with this is its awful, and strangles the 1800. It is better to either obtain an MGA long centre branch exhaust manifld system, and use just the single carb off the 1800 Marina, cutting off its single 'Log' inlet manifold from its exhaust part, OR finding a Riley 4/68, 4/72, M.G. Mk3 or Mk4 exhaust cast manifold, and use the single 1800 carb, or even better the MGB/ Marina 1800TC system, (both are the same twin SU set up.) You need to study this carefully before deciding But I will tell you that an 1800 with an A60 inlet system will have trouble making 75bhp, where as a twin carb system using a LCB MGA exhaust, and a MGB cam, may well push out close to 95-98 bhp.

If you do opt for your old inlet/exhaust system, at least fit a K&N air filter, with the rich needle for your car (usually an 'M' for the A60 and two 'FU' for the 4/72.)  If you fit the twin carb set up, ( those using their old Riley or M.G. items, these SU HD4 are quite OK for an 1800,) the K&N filter are by far the neatest arrangement, and look good with a ribbed alloy rocker cover.................more money. The standard Marina 1800 single and twin carb air filters a very difficult to get under our bonnets, and away from the inner wing panels, hence my use of the KBiN, that increases aimow quite a lot, hence more BHP. Adapting the choke cable and throttle control needs thought, its easier to make the throttle cable operated as well for twin carbs.

Other bits and pieces...............most 1800 engines have a mechanical petrol pump. You may want to use it instead of your boot mounted SU electric pump, or to just remove it and fit a blanking plate, picture Nol item 29 and 30. The radiator on you 1622 Farina may need uprating to a FOUR CORE unit to cool the 1800 engine. Any radiator specialist will re-core it for you. The 1800 operates on a 15psi pressurised cooling system, you need to get a 15psi radiator cap. Renew all the hoses including the heater hoses, 15psi is quite a strong pressure, it will soon find weak hoses. If you fit an alternator as suggested, the engine mounting on the steering side will need some shims under it to get the bigger altemator body off the steering box, and also use the 1800's shorter fan belt helps. You may need to file the inner edge of the post 1964 Farina steering box reinforcing bracket to clear the side of the alternator. The 1800 cylinder head has a lump at the rear, this can hit the heater platform on the bulkhead. You need to loosen off mounting bolts, elongate holes with a file, and move things about, but beware, as the front of the sump can hit the rear of the suspension cross member. The Marina sump has a large steel lug at the rear to brace the gearbox to, where our gearbox has no mountings. Either cut this lug off, or if you have a 16AA,16GF, engine, whose sumps will fit an 1800, use this. The earlier sump has a different top edge shape, (see picture No 11 for early 1622 pre about 1966, and for post 16AA,(16GF), and 1800 sump.)

Picture No 10 shows the five main bearings inside the 1800 sump, compare this complexity with that of the three main bearing crankshaft shown in picture No6.

If this all makes you go faint, and you have about f1800 spare, the MGOC will sell you abored out 1800 to 1950cc, leadfree, for the MGA 1600 Mk2, ready to fit. The MGA 1600 MkZ uses our 1622cc engine and gearbox. This 1950cc engine produces about 110bhp.

To make proper use of the 1800 you have fitted, his advisable to use radial ply tyres, a 3.7 diff from a pre-April 1967 MGB ROADSTER ONLY banjo rear axle, (fits the post 1962 Farina axle only with 'star' splines,) and if you can afford Healey 3000 front dise brakes with servo. The huge drums of the Farina can cope, but be careful. If you have the MGB or 1800TC engine with its hot camshaft you may well need an oil cooler. Your main problem will be insurance if you are under 30 and live in the UK.

Where do you get the bits? (UK Listing)

MGOC Spares dept, (complete engines,) 01954 230928 fax 01954 231923

Lancaster Insurance, (for a quote BEFORE you do it!!!) 01480 484800.

Copies of MGOC magr~ne for adverts, 01954 232801.

Copies of MGCC magazine for adverts, 01235 555552.

M.G. Enthusiasts magazine for adverts, 01294 499261.

MGB engine spares, MGBHive,01945700500.

Mech Spec, 01909 482775.

Sussex MG. 01403 711551.

Ron Hopldnson 01332 756056.

Moss 0800281182.

Brown and Gammons, 01462 893914.

Secondhand used engines, Mech Spec 01909 482775.

Any of the M.G. magazines.

Leadfree heads, 01954 230928.

Vulcan Engineering,OB1 579 3202.

Fuel system spares, Burlen Fuel Services, 01722 412500.