Brad Chapman's 1975 MGB GT with Rover 3.5L V8

Brad Chapman's 1975 MGB GT with Rover 3.5L V8

as published in BritishV8 Magazine, Volume XVII Issue 1, July 2009

Owner: Brad Chapman
BritishV8 UserID: evoconvert
City: Bicton, Western Australia
Model: 1975 MGB GT
Engine: Rover 3.5L V8
Conversion by: Owner

Engine: Rover 3.5L engine. Holley 600cfm with vacuum secondaries on an Offenhauser "360" (part number 5165) single-plane intake manifold. Pertronix Ignitor ignition module mounted inside the dizzy in lieu of breaker points. Rebuilt SD1 starter motor. Pre-facelift P6 alternator bracket.
Cooling: modified stock MGB (four cylinder) radiator with relocated ports.
Exhaust: custom headers (purchased "used" from a racer.)
Transmission: Toyota Supra alloy case 5-speed manual transmission with Dellow bellhousing. Dellow clutch kit including transmission mounts, slave cylinder, throw-out fork and bearing, etc.
Front Susp.: stock MGB.
Rear Susp.: stock MGB.
Brakes: stock, except for MGB GT V8 front calipers.
Wheels/Tires: Minator 15x6 8-spoke alloy wheels.
Body: Sebring front and rear valances. (The heavy rubber bumpers have been removed, and a 1974-spec grille has been installed.)
Interior: stock MGB.
Weight: 1020kg (2248Lbs).
Completed: February 2009.
Comments: Where to start! I think the main areas of concern I had were the engine location and the selection of which gearbox to use. I purchased the engine mounts from the MGOC website. In hindsight, I believe I could've placed the motor slightly further back (e.g. maybe an inch or so.) However, the height is good and I have enough clearance to remove the sump pan with out lifting the engine. I decided to use a Toyota Supra gearbox. In Australia they're readily available with four different length casings (18, 19, 20, and 21 inch long respectively). I think the longest version is the most appropriate. I found that it located the gearstick very near the MGB's original location. The box I used is referred to as a "w55" box and has very similar gear ratios to the MG RV8 model. These boxes are good for about 500hp, so they're virtually break proof. The Dellow bellhousing was a easy install. It clears the tunnel by about 10-12mm either side, so I did not have to modify the tunnel at all. At the time of writing, I have not upgraded the differential yet but I intend to do that soon. (I'd like a limited slip differential.)

completed engine installation

Holley 600 (vacuum secondaries) on Offenhauser 360 single-plane intake manifold.
Holley 600 (vacuum secondaries) on Offenhauser "360" single-plane intake manifold.

dual exhaust pipe routing

Dellow transmission crossmember

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How It Was Done

Custom four-into-one, block-hugger headers.
Custom four-into-one, block-hugger headers.

Toyota Supra W55 5-speed gearbox.
Toyota Supra W55 5-speed gearbox.

Dellow bellhousing.
Dellow bellhousing.

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modified radiator shelf

modified slam panel

modified turn signal mounting

single circuit, servo-assisted brake system

Installation of a Sebring front valance
Installation of a Sebring front valance.

Installation of a 1974 MGB grille
Installation of a 1974 MGB grille.

The Completed Conversion

very pretty new paint job

stock MGB GT interior

Sebring front valance.

Sebring rear valance.

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