MG MG Farina Magnette - 5 main MGB installation
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| I am in the process of restoring my MK 111 and hopefully will be driving it to the NAMGAR GT this summer. I tested the original 1500 and one cylinder is low in compression. I happen to have a rebuilt MGB 1800 engine and would like to install this in the Magnette. Has anyone done this? Does anyone have a list of the necessary steps to complete the change? Thanks, John Orrell |
| J Orrell25/01/2010 at 02:19 |
| Can be done. You will need the MGB gear box with or without O/D. Your G Box is a little different. With the extra H P I don!t think the present box would cope for to long. MGB Diff-- May be drive shafts or fit your spider gears to accommodate your shafts. Different splines. You may need to cut away the transmission tunnel to allow the starter motor to clear. This means you will need the MGB drive shaft as well. You will also need to change your throttle linkage set up. I have a MK 111, and had looked into doing the transplant personally feel you are better off spending the time, and money on the original motor. I feel most of my points are correct someone else might like to confirm, or deny. Regards Peter |
| P R Jericevich27/01/2010 at 09:42 |
| If you can find an early three-bearing MGB engine, it will drop straight into your Mk3 easily. The later five-bearing engine is totally different at the back end. The 3 bearing engine uses the Austin Cambridge A60 gearbox. The 5 bearing engine uses the stronger gearbox of the Sherpa van. It is not practicable to fit the later gearbox unless you are ready to cut out a lot of the transmission tunnel. You would be better off using the 5 bearing engine onto your current gearbox. To do this you will need to removed the clutch, flywheel and rear engine plate from the 5 bearing unit. Then you will need to have the centre of the 1500 3 bearing engine plate accurately turned out to take the rear oil seal of the bigger engine, as well getting the smaller 1500 flywheel drilled to fit the 1800 crankshaft end. That way you can use your current clutch and starter motor. Fitting a 3 bearing 1800 MGB engine is far easier, as I said. The problem is finding one. If you email me direct I'll send you an article on tuning the 1500/1622 engine to 90bhp as per the MGA 1600 mk2 unit. Neil Cairns. |
| Neil Cairns17/02/2010 at 16:21 |
| Neil The first 5 bearing engine MGB engine mated to the 3 syncro gearbox ie the MGA type box (and A60?) willsurely fit easily George |
| G R Wilder17/02/2010 at 20:46 |
| John, Speaking as the Magnette representative for NAMGAR, we WANT you and your car at GT 35!!! Nobody has asked, but is your rebuilt 1800 a three-main, or a five-main? If the original engine number tag is still present, the three-main would be an 18G or an 18GA. If it is an early five-main, it would be an 18GB. For your conversion purposes, the big differences between the three-main, the five-main 18GB and the later five-main engines would be in the oil-seal, back plate, flywheel diameter, presence of rear main oil seal, flywheel bolt pattern and starter position. So, what is your rebuilt MGB engine? Three main; five-main 18GB or later? There are also compatibility problems regarding pilot bushings and transmission first-motion-shaft diameters. This sounds unduly complicated but once you sort out what you have vs what is available and what conversions are possible, you end up with a rather simple decision. If you're upgrading to an 1800, please seriously consider the 5-speed/overdrive possibilities. Whatever "B-block" engine you end up using, there is an overdrive transmission option that will turn your Mk III into a real mile-eater on the expressways. Now: while I have a Mk IV Farina Magnette sitting forlornly on the carport, my experience is with converting Z Magnettes. Twice, I have converted them to 5-main 18GB engines with the Rivergate/Datsun 280Z five-speed transmission options. While I have yet to do this with my Mk IV, I anticipate that whatever will fit into the Z Magnette transmission tunnel will also fit into the Mk III tunnel. (' Hope I'm right!) I don't know the final drive ratio on the Mk III (on the Z Magnette it was 4.55:1) but if it's anything less than the MGA 4.3:1, I would swap it for a 3.9:1 MGB banjo-axle rear end. You re-use the spider gears from the donor MGB. It's about a two-hour job. My own prejudice is in favor of the Rivergate/Datsun 280Z conversion. It's a breeze to put together thanks to Rivergate's superb engineering/design. But you might like also to consider the Ford Sierra Five-speed kit sold by Moss and Hi-Gear Engineering in the UK. It's about twice as expensive... If my Z Magnette experience applies to the MK III, I would caution you away from an MGB overdrive conversion. I may be wrong, but these transmissions require a substantial modification to the transmission tunnel in the Z-series cars. Early MGB Laycock D type overdrive transmissions may be less intrusive, but proceed only with utmost caution! I love the five-main B engine/Rivergate-Datsun transmission conversion on my ZB Magnette and I see no reason why such a conversion wouldn't work on a Mk III. It turns out that the driveshaft conversion on the Z-series cars is unbelievably simple: ream out the front yoke for a Datsun U-joint. That would probably apply to a Mk III driveshaft also, but DON'T take my word for it!!!! I hope I'm right, but have no reason to be convinced! Whatever happens, I want to see you at GT35 in Wisconsin this summer! Allen |
| Allen Bachelder 29/03/2010 at 03:46 |
| Allen can you give more anymore details on the 280z gearbox swap, i like the sound of that |
| s lee30/03/2010 at 08:15 |
Yippee - some activity on the farina page ! Regards Gobby 
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| Gobby13/04/2010 at 10:26 |
| Gobby, Damn, your Farina looks drop-dead gorgeous. S Lee, Rivergate's website is http://www.rivergate5speed.com/rivergate.html Right now, I'm getting malware warnings when I try to bring it up, but their email address is rivergate5speed@bellsouth.net. The kit was really designed for five-main MGBs, but Will Perry (owner) tells me he can work with just about any B-block engine. The kit includes a conversion backplate, already machined to accept a five-main oil seal, and a new flywheel which is smaller than the one used on later five-main engines. I'm thinking it's the same size as the 18GB flywheel. It uses a '68-and-later MGB starter, an Isuzu Amigo 2.3 liter clutch disc ('89-94), and a 280Z slave cylinder controlling a 280Z roller throw-out bearing. The 280Z box is designed for a much bigger engine - and is bullet-proof in this conversion. It is also smaller than the three- and four-synch MGB transmissions. It goes in the Z Magnette tunnel with no alterations - except the shift-lever hole needs to be cut back about two inches. In the Z Magnette, the original driveshaft length is perfect. All that is needed is to ream out the front yoke to accept a Nissan U-joint. Naturally, I'm thinking of a similar conversion for my own Mk IV. With the five-speed and 3.9 MGB rear end, the Z Magnette becomes an extremely viable, quiet, 75-80 mph turnpike cruiser. ' Hope this helps. Allen |
| Allen Bachelder 14/04/2010 at 05:30 |
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