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MG MGB Technical - Question on Steering gear and Engine block

What year did the US MGB change to the longer steering gear shaft?

Also, Are all MGB Blocks the same? That is, with the exception of adapter plates, can any MGB engine block be used in any MGB?
BEC Cunha

Bruce,

Any MGB block will fit in any MGB, but there were some changes. 3 to 5 bearing being the first to jump to mind! Also later blocks had a blanking plate over a hole for a mechanical fuel pump used on some BMC cars. No doubt a few other changes, but with the correct front and back plate they can all fit in any car as far as I am aware.

Iain
67 BGT
I D Cameron

another difference that comes to mind is the generator mount on the early blocks is different than the alternator mount on newer blocks. Not that difficult to get around though. I have a 67 block in my 75B.

I'm not too certain about the steering gear shaft question. The only thing I can offer is that they did change the rack when they raise the height of the vehicles when rubber bumpers were introduced, as the angle of the steering rack was changed. I do believe that the length of the steering column may have changed as well, since the later set up would require a longer column. (not too sure on that one though). If that's the case, this change took place in late 74, where the vehicles build for 75 would have been raised.

~Dave
'75B

Dave Ryzuk

Bruce,

I second what the guys above are saying. The big change over was the rubber bumper cars. The engine mounts changed and the physical engine block changed, with different mounting points for the mount and shorter oil gallery.

At the same time the steering rack changed as well at the accompanying cross member. As far as I know the chrome and rubber bumper engine blocks and steering gears are not interchangable.

I do not know enough about the early 3 main and early 5 main engines. I understand the steering and suspension wise all chrome bumper cars are the same with some modification to grease fittings.

Hope it helps,
Shareef
Shareef Hassan

AFAIK, if you fit the correct front plate for the engine mountings, any block will go in either car.

My engine certainly didn't start off in an MGB, the hole in the crank is about 1" too short, but it is in, and running fine.
Martin Layton

Bruce. The steering column was changed with the 74 1/2 models, the first Rubber Bumper cars. At that point, the engine compartment was enlarged to make fitting the V-8 engine easier.

As to blocks, all of the five main bearing blocks are inter-changeable. The 18V blocks had the blanking plate for the mechanical fuel pump and the shorter oil galley due to same. But, they will interchange.

The back plates of all the 5 main bearing engines, from 1968 onwards, should be the same. They use the same transmissions and same starters. The front plates differ between the chrome bumper and rubber bumper cars and the correct plate for the body style needs to be used.

The pilot bushing/spigot bushing differed with the earlier engines having a 1.5" bushing and the later models having a 1" bushing. Several people have reported installing the 1" bushing in the earlier models without any problems.

Les
Les Bengtson

The forward mounting of the radiator, as in V8 practice, wasn't commonised with the 4-cylinder car until the 77 model year. At the same time the V8 mounts were adopted for the 4-cylinder car, and hence the different front plate. I'm not aware of any other enlargement of the engine compartment, V8s had been installed since early 73.
Paul Hunt 2

Thanks all.

My steering on my 67 is still tight even after a full rebuild of the front end. When I got the car, I checked the steering and it was dry, so it well may be worn. Lubing it did loosen it up considerably, but the steering just does not fee correct.

I am looking to purchase another steering gear. They come up frequenty on e-bay. That will give me one I can install while I rebuild the original. Sounds like 74 and prior should be correct.

The block question is similar. I would like to have another engine that I can rebuild at my leasure so I have a spare. 67's come up from time to time, but are not as common as the 70's engines.
BEC Cunha

Bruce,

Is the steering rack shiommed correctly? If it is slightly misaligned this can cause heavy steering when all else is in good nick.

iain
I D Cameron

Hi Iain

That is a good question. The early MK1 is still a bit of a mistery to me on setting up the alignment correctly in that you can adjust the steering column (no direct mount to the floorboard, just a plastic boot) or the shims on the steering gear.

I built one of the pointing devices and both shafts are aligned.

As for shims. I assume if I loosen up the bolts that hold the shims, it should loosen the steering if it were to tight. I can give that a try also.
BEC Cunha

Are we all sure that there wasn't a change in steering pinions beginning with the '68 US export models? I was under the impression that '68 was the first year of US collapsible steering column requirements. This in addition to the changes with the RB cars in mid '74.

Engine mounts on the US cars changed at tourer #360301, GT#361001, with the switch to rubber bumpers in 1974. At that point, the bulkhead was reshaped so as to slope backward on each side toward the center recess, instead of being perpendicular to the axis of the car. This to make room for the V8. Strangely, the radiator was not moved forward until 1977 when V8 production was but a memory. I suppose the redesign was scheduled back when V8s were still being built and continuing production was still anticipated.

As to interchangeability of engine blocks, unless a five-main crank can be used in a three main block (which I doubt) the three-main engine would require a three-main flywheel, thus requiring an early starter, early backplate, and a 3-sync transmission. Placed in a later model car, that might require opening the shift lever hole forward a bit. Interchangeable? Yes, but with some caveats.

FWIW,
Allen
Allen Bachelder

This thread was discussed between 14/05/2007 and 18/05/2007

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