1800 MGB engine

[casper171072]

What are the issues to consider fitting a five baring MGB engine?  I have looked a some past comments but I'm still not clear.  I have the chance of getting hold of one as a side project to rebuild.  I rebuilt an A series some years ago and found it a great experience.  I don't want to bother doing it if its too much messing to get it into the car one day.  I also don't want to do the original engine and have the car off the road for ages.

thanks in advance

[anglia67]

Hi,I'm fitting mgb engine & overdrive box so bit of tunnel work& bell housing.
Main items for just engine would be rev counter going from cable to electronic,exhaust manifold,I'm making my own using a stainless steel mgb tubular manifold,
Front engine mounting plate I've used Riley original,clutch I'm not sure about onto 1.5 box. Ideally I think you'll need mgb carbs.
Cheers Allan

[casper171072]

I was looking to keep the original gearbox as I assumed that would be easier. Front plate i can just take off the existing engine but I am told there is something to be done with the back plate rear seal and clutch but not sure of the details

[canuck]

Richard,
I am doing this swap but taking the easier road of the 3 main engine. 

Not sure about the need of front engine plate, as Alan suggests. If your target 5 main engine is coming from a RB MGB or another car model then yes otherwise the CB MGB engine plate is fine. 
FWIW keep the timing chain cover and damper from the MGB engine. Having the timing marks on top is a bonus. 

Your biggest challenge to mate up with the standard Riley transmission will be the engine back plate, flywheel and starter motor. The easiest being an early 1800, 3 main rear engine plate with early smaller diameter flywheel and inertia starter motor. These are all needed to fit the smaller 'unique' Riley bell housing of the transmission.

A few caveats to the 5 main choice;

the spigot bush in the crankshaft will need to swapped out to match the smaller diameter input shaft of the Riley. Not an issue Moss offers a stepped bush for this 
the crankshaft to flywheel is different, bolt pattern etc. so you may wish to do some investigating. 
the clutch cover plate/flywheel will need machining, Riley/MGA cover plate uses 2 locating dowels whilst the MGB use 3 dowels.
  
the oil filter system will want swapping from Riley to the MGB engine. MGB came fitted with oil cooler and some fittings will not align to Riley.



I keep my Riley H4 carburettors but merely change out the metering needle to a #MB which is what was fitted to a pre smog MGB, all be it to HS type carburettors.

I have previously posted my exhaust header solution and this applies to either engine.
Let me know what else you need I may have forgotten some other details. 

salut
Bruce

[tjt77]

as suggested above.. 3 main MGB is a direct 'bolt in' swap... and is the most simple route to more power and greater engine strength.. (95 BHP in standard form) it also has a stronger crankshaft than the std 1500cc Riley engine.. main bearings 1/8" bigger in diameter..

to fit a 5 main to car with existing riley gearbox:- you need to modify the Riley backplate to fit the MGB oilseal.. .and fill in the oil drain slot (a machinist can cut the hole to fit the seal..the slot can be filed with epoxy such as 'belzona111) you do have no provision for mechnical tach on the % main B series engine .. so either swap the tach faceplate into an early MGB 'smith' tach.. or fit a modern electronic movement into your riley tach ( a better route.. the smith tachs are not very accurate or reliable)

If using the whole MGB engine and box, there are a number of issues to resolve :- bell housing clearance on rack.. position of gear lever :- early non sysnchrop 1st B box has same lever location.. early overdrive box has lever about 1 1/2" rearward of riley position.. later full synchro box also has the lever further back by 2" plus and the whole casing is MUCH bigger..it wont fit under the floor without some hacking... a far better bet would be to adapt a ford T9 kit ... 'hi gear engieering' will likley supply the appropriate bell housing , drive shaft front part, and other bits you need..