Randy Forbes' 1971 MGB-GT with Buick 231 V-6
(originally published in British V8 Newsletter, Volume 7 Issue 2)
By: Randy Forbes
City: Breaux Bridges, LA
Model: 1971 MG MGB-GT
Engine: Buick 231 V-6
How It Was Done
|Engine:||1982 (?) Buick 231 V-6, fresh rebuild to stock specs, has a factory 4-bbl manifold,
(possibly from a 4.1 V-6) with 450 cfm Holley spreadbore.
|Transmission:||GM T-350C automatic, still original, but needs shift points recalibrated.
Several options available from the aftermarket. Plan to connect lock-up torque converter.
|Exhaust:||tubular steel homemade headers with 1-1/2" x 32" primaries and 3" x 12-1/2" collectors,
exit through fenderwells. Duals, through turbo mufflers, to rear mufflers, to rear bumper.
|Brakes:||braided stainless steel hoses and semi-metallic pads. Otherwise stock.
|Wheels/Tires:||stock Rostyles freshly painted with silver and teal blue recesses.
Yokohama Avid T-4 185/65 x 14 all around.
|Suspension:||(rear) stock with exception of 1980 roadster springs, lowered rear 1-1/8".
|Cooling:||MGB-GT V8 radiator (rubber bumper version), Still waiting to see if it can
cope with southern Louisiana summer heat! Oil cooler and automatic transmission
|Rear End:||stock 3.9 MGB. Presently converting to 3.31 MGC wire wheel axle.
Modifications to hubs allowing use of longer disc wheel axle for correct
width will be fitted soon.
|Instruments:||stock - little more than an indicator that engine is running or is moving - great error!
|Conversion By:||owner, with occasional outside machine work, exhaust tubing bent, etc.
|Sources:||most parts came from a variety of MG's already in my possession
('68 MGC-GT, '72 & '73 roadster, and T, and lots of parts from 1980 MGB).
Rest from commercial/local sources including racing products specialists.
|Weight:||curbside weight with full fuel tank = 2360 lbs., 1200 front / 1180 rear as
weighed on truck scale.
|Recommendations:||support engine from front crossmember at rearmost attachment points to allow
for rearward and low setting engine. Oil pan still shielded by crossmember at
rearmost attachment points to allow for rearward and low sitting engine. Oil
pan still shielded by crossmember. If I was starting over, I would start with
a better car and more money. For the next car (there will be more) I'll
use a Chevy 4.3 V-6 for my 74-1/2 GT.
I purchased my first MGB, a 1973 roadster, new while living in Detroit at age
eighteen. The following month there wass a single column news release in Road and Track's
European Report... Americans would love it... MGB/GT V8 for home (UK) market only".
I've wanted one ever since. Growing up a Motor City gearhead and having older hot
rodding brothers, I knew what the BOP 215 was before Rover got wind of it. At age
15, I had performed a valve job and overhaul of a girlfriend's father's '62 F-85
(two barrel version).
The 1971 MGB-GT, when I acquired it in the spring of '91, had an aluminum V-8 in it. I'm afraid it was a real hatchet job, though. Anytime a hole was required through the body t was made with a screwdriver punched through with a hammer. No craftsmanship! There was no transmission, but the clutch and bellhousing was attached to the engine. The engine itself had three broken pistons. For reasons I cn only guess, the rocker tips were built up with weld and the result was valves and pistons crashing together.
Currently the car needs paint and interior trim as well as upgrades to the still stock brakes and suspension. I have put 10,000 miles on it in just five months going back and forth to work. It's great for passing on two lane roads! I was able to keep the engine low in the car by using the BOP 215 motor mounts with brackets on the front crossmember, not as usually placed on the frame rails. Since the inner fenders were already butchered, I made my own headers with 3/8" flanges, 1-1/2" x 32" primary tubes and 3" x 12-1/2" collectors - the rest was simple. The only real work was cleaning up the mess from the previous swap job.
I did have to modify the firewall area, as per Roger Williams' book. The right side was modified for more space at the rear of the valve cover and the heater box cavity was eliminated to clear the T-350 bellhousing. Trans tunnel was already bashed toward the driver's right foot. Heater is now defroster only - not a problem in southern Louisiana. I do want to go to tube shocks next, along with getting the MGC/GT 3.31 axle installed. Using the wire wheel axle on a disc wheel car requires the wire wheel rear end housing and disc wheel axles and hubs.
I've left a lot of room to further develop performance of the entire car, once I figure out who's bigger brakes I can fit, etc. The 1971 MGB/GT 3.8 is my "mule" to develop best route to take with my other road car - the 1974-1/2 GT. For the '74-1/2" I want to use a 4.3 Chevy V-6 (it's 3/4 of a 350 small block V-8) and a Rover 5-speed transmission. I already made the adapter to put the TR-7 5-speed onto GM pattern bellhousing.