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MG MGB GT V8 Factory Originals Technical - RV8 motor mounts, why?

Hi all,
I am in the process of planning a conversion of my ´79 US specification tourer into Rover V8 power.
I have read that the RV8 uses different thickness of the motormounts left/right and I am trying to figure out why. I have come up with different theories. It is clear to me that a slight tilting of the engine is beneficial for some reason. 1) Is it to clear the prop shaft from the handbrake in the prop tunnel? 2) Is it to enhance bonnet clearance in some area? 3) Can it be used to enhance clearance between my ´79 blockhugger manifold and steering shaft. 4) Would #3 decrease the clarance between the propshaft and the handbrake in the tunnel? How should they be used?

Any ideas and experiance?

Thank you in advance.
Erik
Erik

Erik,
I offset my engine, Buick-Olds, 1/4 inch toward the right side. The reason for this was to provide more clearance between the left-hand, rear exhaust and the steering shaft. As a consequence, the transmission is closer to the right side of the tunnel, so that the u-joint is too close. Judicious use of an air hammer, creating a small 'dome' in the tunnel took care of that. Fabricating my own motor mounts resulted in the one for the left side to be 'wider' than that for the right in order to align the engine in this offset position. Sounds like the RV8 may have been designed with the same issues and results. Best, Joe
Joe Ullman

The RV8 engine mounts are of differing thickness to provide additional clearance to the steering shaft.
Scott

Erik
The MGBGTV8 had engine mounting of equal thickness- same dimensions as the 1800 but harder rubber (go to Clive Wheatley and not Moss). This arrangement kept the rt hand cast iron block-hugger off the steering with only one spacer(cars all made with RH Steering).

The RV8 uses the same engine mounts on a 3.9 with a FI Plenum chamber - the engine is the same as the RR - and the top of the unit sits higher than the OE GTV8 SUs. The factory therefore created space with a bonnet bulge - even this left the plenum rubbing on the bonnet so the left hand mount was reduced in size to get the motor as low prudent - there is still not much room on top and it is sometimes necessary to cut down the plenum as well as fit the slimmer mount.

If you fit a slimmer mount on the opposite side to the steering - you will also have to fit a second spacer on the steering side thus losing some of the height advantage. The real answer is to use RV8 exhaust manifolds to get the full advantage.

Over-long answer - sorry. Another answer is to go for the GTV8 fit with Sus & original bonnet.

Hope this helps

Roger
RMW

Roger,


" you will also have to fit a second spacer on the steering side thus losing some of the height advantage."

Please can you explain why you need the second spacer. Is this to stop the starter motor touching the steering shaft or to balance the engine?

RIchard
R Weston

Richard
Yes - the engine height reduction resulting from the thinner mount has the effect of bringing the blockhugger closer to the steering - so one needs the second spacer to keep a clear route under the manifold (for the steering).

The height is only a problem with the FI plenum and even that can be filed down.

Erik
I meant to mention that you don't want to tilt the engine - that will reduce clearance under the bonnet AND secondly, the 3.9 engine had a nasty little proboscus on the port side which fouls the OE exhaust manifold - I suggest you 'offer up' the manifold with the engine out of the car so that you can identify this piece of ally and file it off.

It's a tight fit but it's not difficult and the effort is very worthwhile.
RMW

Thank you all for your help.
Next weekend I will go and pick up a newly rebuilt 84 SD1 Vitesse engine and box.

Erik
Erik

This thread was discussed between 17/05/2004 and 19/05/2004

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