Gordon L. Oxford and Mary Ann Henley's 1970 MGB-GT with Ford 171 V6

(originally published in British V8 Newsletter, Volume 6 Issue 2)

By: Gordon Oxford and Mary Ann Henley
City: Daleville AL
Model: 1970 MG MGB-GT
Engine: 1978 Ford 171 V-6

How It Was Done

The MGB V6 Conversion manual was purchased from V-6 MGB, P.O. Box 741992, Dallas, Texas 75374. The engineering in this manual was done by John's Cars, Dallas Texas and later all copyrights sold to this company. No phone number available, just mail order. The detailed engineering drawings are sufficient to fabricate the necessary mounting brackets with little difficulty, but they are available by mail order.

The plans call for a GM alternator and Headers only available by mail order. The headers are built by Kirk Racking of Birmingham AL. However, they will not sell direct to you. My headers were purchased from John's Cars, but I did have to modify them to fit. The 90 degree oil filter adapter I could not find or is not available, so I used a remote oil filter and stock MGB oil cooler.

I started with a 1970 MGB GT. I cut off the existing motor mounts flush with the frame, also the radiator mounts. I cut the pan in front of the radiator from frame rail to frame rail for the 1977 radiator using stock side mounts purchased from Glen Towery. This also allowed clearance for the AC unit and fans, fans later removed (not needed). The 1977 radiator uses a 14 inch fan behind the radiator instead of the existing engine clutch fan. I installed a 1977 MGB front crossmember with stock 1970 suspension and steering rack, the rack shaft had to be lengthened about 1-1/2" to fit. I also installed a 3/4" inch sway bar in the front and plan to install a stock 1977 MGB sway bar in the rear. I used the larger radiator (4 inches taller) for more cooling due to A/C unit, besides I didn't like the listed mod's for the stock 1970 radiator.

I purchased a complete engine and transmission unit from a 1978 Ford Mustang with 78,000 miles showing. The mild rebuild was mainly to check the engine and modify known weak parts. ARP rod bolts, new cam with aluminum cam gears. The 60-degree V6 has a 3.66" bore and 2.7" stroke. I initially used the transmission which came with the engine, a RADS 4-speed with integral shifter. First gear 4.07:1. The shifter comes thru the tunnel about 1 inch behind the stock shifter point. I needed a higher rear end ratio so I used a 3.3:1 MGC wire wheel rear end with disc wheel spindles, this narrowed the rear track enough to use Datsun 240Z 14 by 6 aluminum rims. I have since changed to a 3.9 MGB rear end and a 1988 T-Bird Turbo Coupe 4-cylinder T-5 transmission. 3.94:1 first gear, 0.81:1 fifth gear. I recommend a T5 from a V8 because the front main shafts are about 1" longer and will fit without modification. I had to modify the pilot bearing to get the 4-cylinder to fit, a bronze pilot bushing from a Chevy pressed in and did the trick for me but I read something from Colorado where they're making a bushing for the 4-cylinder T5. The V8 T5 has a 3.35:1 first gear and a 0.68:1 fifth gear. By using this transmission the stock 3.9 rear end is more than compatible. 2.56:1 final drive in fifth gear. The present configuration I'm using gives 3.12:1 final drive, and the V6 with its short stroke likes RPM which is about the same as a MGB 4-speed overdrive final drive ratio. Although this configuration does make the car really go, first gear is really low.

An MG Midget slave cylinder was mounted halfway down the transmission, with a spring return, to activate the clutch arm. Clutch and flywheel are stock '78 Mustang. The driveshaft I used came from a MGC and fits the U-joint for Fords. This also requires a MGC rear end or the MGC rear end flange installed on a MGB rear end, it fits.

The exhaust goes from the header's 2 inch into a 2-1/2" single exhaust fitted with a Super Trap muffler, 2-1/2" inch inside diameter. This muffler allows adjustment of the exhaust back pressure and noise level by how many discs are used.

The T5 shifter comes through the tunnel about 1-1/2" forward of the stock location. I have had to modify the rear end due to the wheels contacting both the inside and outside of the wheel wells during hard cornering. I used a Panhard Rod to stabilize the rear end and it does more than just stabilize the rear end, the handling has improved a lot. The how to build the Panhard Rod came from the July 1991 MGC Newsletter, page 15. This is a rather simple fabrication. I have also installed tube rear shocks which I like very much.

Still on my list of to do mods are a set of traction bars, and beefing up the rear spring mounting locations, Fiero seats, minor body work, (got a deer with it last year but only minor damage). Paint and Datsun 260Z six point star rims installed.

This engine is a lot easier to get than a Rover V-8 and has about the same bore and stroke. It has a lot of power for the A/C unit and whatever and is a lot quicker than my MGC GT.