MGB V8 - Bodyshell Mods

 

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In order to fit a Rover V8 into a MGB bodyshell, you need to make certain changes. These will depend on the bodyshell you begin with - for example the later rubber bumper bodyshell will need far less work than an early shell. All that you need to know is well documented in an excellent book that I would recommend to anyone starting a similar project.

   How to give your MGB V8 Power  ISBN: 1904788939

On this page I will try and describe the modifications I have made and the thinking behind my decisions.

The Core Bodyshell

My core bodyshell is based on a post 1976 rubber bumper MGB Roadster Heritage Bodyshell. BMH or British Motor Heritage Limited was established in 1975 to support owners and the marketplace by putting genuine components for classic British cars back into manufacture, using original tools wherever possible. Since 2001, when the company was acquired from BMW, it has been successfully run as an independent company.

This shell was chosen as all the later shells had a number of the modifications required for the V8 as standard including different inner wings and bulkhead panels. However I did not want a Rubber Bumper car in the end so the shell was converted to accept Chrome Bumpers by the MGB Hive before delivery. The other pre delivery modification was to have a height extension installed in the transmission tunnel to accommodate the taller LT77 5 speed gearbox (of SD1 fame).

It hadn't been primed when it arrived, hence the wet looking paint!

Exhaust Header Holes

The standard headers on MGB V8's were cast affairs that had to squeeze between the engine and the front chassis rails. There are similar tubular ones available as a replacement but in order to get the breathing as good as possible in this installation it is widely accepted that the best route is to use headers similar to those used by Rover on the MG RV8 in the early 90's. These are a 4 into 1 arrangement that goes through the inner wing. The MGOC can provide a template as to where to cut the holes and also the RV8 pattern strengtheners to put round the edge.

        

After some interest I have scanned the templates and saved them as pdf's. Originally they are on A3 - the line down them is the middle of the piece of A3 if that makes sense!

Header Template LH a

Header Template LH b

Header Template RH a

Header Template RH b

Twin Exhaust

Right from the start of this project I have been determined to have a twin exhaust system. Why, because that is what V8's have! and I love the sound that V8 TVR's make - so that is what I am aiming for.

Initially I feared that I would have to have a bespoke system made up, but then the MGOC produced one when they did the MGB Supersports a few years ago. The only draw back is that it won't fit with the fuel tank in its normal position. It is likely that you could move the tank a couple of inches towards the centre line as others have done - but I splashed out on an Aluminium tank designed specifically to work with this exhaust.

The kit comes with all the relevant fitting kit, but obviously the bodyshell needs mounting points adding and an additional cut out in the rear valance.

              

Bonnet/Boot Hydraulic Struts

Little things to make life easier! Two on the bonnet, one on the boot

  

Radiator Support Panels

When trial fitting the radiator I have discovered that the radiator panels don't appear to have been fitted properly by Heritage. Either that or the work done by the MGB Hive to convert from rubber to chrome bumper has created the problem. They appear to have welded in a section from the bottom of the radiator support panel to the main front leg that isn't there on other chrome bumper cars. By cutting this link on one side I managed to fit the radiator but was still not happy with it.

So I ordered two replacement panels to weld into place. Whilst I was doing that I took the opportunity to add 3 holes to the left hand (near side) panel. As standard this is solid with no holes whereas the right hand one has 3 holes. Given that the air filter for the Hotwire system sits right behind the LH panel it seemed logical that I should make the effort to get some cooler air to it!. In or to have a professional looking job I purchased a special tool to "bell" the edge of the hole from Frost.

   

RV8 Brake Servo

In terms of brakes I had intended to use the RV8 front cross member complete with RV8 brakes. So it seemed logical to acquire an RV8 servo and master cylinder both of which were available from the MGOC. I later decided to go with the Hoyle front end and I have got a pair of 4 pot calipers from the MGOC although they originate from Coopercraft a Jag specialist. Not the lightest of calipers! but I am sure they will be fine - I have just got used to handling AP Racing calipers for Monaro's recently!

In order to fit the RV8 servo I had to remove a plate from the inner wing as the servo is bigger than the standard B item. But no problem with a spot rivet drill again from Frost.

Gearbox Cross-member

In order to accomodate the LT77 (SD1) 5 speed gearbox, changes are needed to the gearbox cross member. These are detailed in "How to give your MGB V8 Power". I chose to cheat a littel and managed to get hold of an RV8 Cross-member which was designed to work with the LT77 or later R380 gearboxes. The only issue then is that this needs to mount further back than the standard B item so I had to drill new mounting holes. On the origonal the bolts that hold the cross member in place go into a tapped plate that is inside the chassis leg. One of my new holes also went through this plate so I was able to drill and tap a new hole. However the other hole missed the plate, but to move the plate would mean either removing the chassis leg or opening the floor up above the leg to move the plate. Neither seemed a good idea so I drilled a large enough hole in the floor to be able to get a nut into the hole and onto the bolt from the cross member.