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MGB V6 & V8 Conversion FAQ

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Mags MGB Avatar
Mags MGB Platinum Member Greg & Maggie
Troy, IL, USA   USA
1972 MG MGB "Monai"
In reply to # 3339038 by MTV OK Folks , Here I am Down under , during the test fitting of the 289 SBF into my MGB it became painfully apparent that the by pass oil filter was not going to fit . Let's just say the space between the oil filter location on the block and the chassis rail is small indeed . Can anyone recommend a by pass adaptor or other solution ? Regards Mick Queensland Australia

This remote kit is extraordinary

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MGTFLE500 Avatar
MGTFLE500 chris yates
Bradenton, FL, USA   USA
1974 MG MGB GT V8
2009 MG TF LE500 "Blackberty"
I f you have fitted an oil cooler...usual place between grill and radiator in front of the fans, there is room for a filter alongside. But then I am an ignorant pom who doesn't know what a 289 SBF is, but I have had both factory GT V8 and V8 roadster conversions

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MG-Maxx Avatar
MG-Maxx Silver Member Charles Waugh
West Haven, CT, USA   USA
1979 MG MGB MkIII "Rumpelstiltskin"
2008 Chevrolet HHR

The problem I had with their kits was the adapter has the hoses coming straight out. I ordered mine piece by piece so that I could get a adapter that had the hoses coming out the side.

90 degree adapters

Hamden, CT

79 MGB - Rumpelstiltskin
Just awakened after a 10 year slumber.
GM 60V6 Gen 3 - 3.5L EFI V6 T-5.

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DIPPY Avatar
DIPPY Bob Davis
La Mirada Cal, USA   USA
1975 MG MGB
1975 MG MGB
I'm using a stk mg setup work fine


Bob Davis

aussielaurie Avatar
aussielaurie Laurie HOUGHTON
Adelaide, Adelaide South Australia, Australia   AUS
Skye, All the responses make good sense so here is my bit. My MGB was a 1973 chrome bumper roadster from the US and when I got sick of the 4 cylinder I converted to a 3.9 V8 Rover engine from a Range Rover,( now changed to a 4.6 ) 4 into 1 MGRV8 headers through the inner wings, a Toyota Supra 5 speed gearbox and a Ford Fairlane 3.2 LSD diff. modified with MGB outer axle housings and custom axles, Front brakes set up, Nascar rotors with Willwood 4 piston calipers, rear brakes are Nissan rotors and calipers. I never considered a carburettor, went with a Haltech after market ECU now controls fuel and ignition and an electric water pump. If I was doing it again here is what I would do differently, modify the firewall to get the engine as far back as possible, cut out the chassis rails forward of the cross member and weld in a reinforcement so I could install as wide as possible a cross flow radiator, replace the bonnet slam panel with one from an MGC. As a Rover engine is about the same weight as the 4 cyl the front suspension remains the same, 600 pound springs 24mm sway bar and hydraulic oil in the shocks, rear suspension stock with telescopic shocks. My "How it was Done" page is on the British V8 site. Laurie, South Australia

rsdgeorge rocky g
Olive Branch, MS, USA   USA
1976 MG MGB
Shows a lot of though and work. If it weren't for people who think and visualize there would be no innovative ideas. I respect a lot of the people on the swap forum, but there are ones who will find issues because they are hesitant to go beyond the norm.

Bernard from France Avatar
Bernard from France Bernard MENNESSON
Here is a 5.0L TVR griffith and his T5 gearbox. no modifications except gearbox tunel

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whitesheep Kenn Prouty
East Selkirk, MB, Canada   CAN
1971 MG MGB
howdy. anyone have thoughts about an auto trans v6 swap? lots of rusty camaro/firebirds out there for low bucks. i am sure it has been done but not as fun as standard trans.any thoughts or advise will help. thanks whitesheep

420 Magnus B
Dakar, Dakar, Senegal   SEN
Laurie do you know if a Rover v8 fits on the original MGA gearbox? I want to buy a MGA I found which still has the original gearbox but no engine.

tjt77 timothy Trevithick
Grass Valley, CA, USA   USA
"Laurie do you know if a Rover v8 fits on the original MGA gearbox? I want to buy a MGA I found which still has the original gearbox but no engine."

No it does not.. the Rover V8 is a GM design and carries the std GM bolt pattern to bell housing.. furthermore the MGA is significantly narrower between the chassis rails and has less overall space in engine compartment than the MGB.. a 3main bearing MGB engine bolts up to an MGA gearbox, provided you swap the backplate from original engine..(as willl any BMC B series engine from 1200cc-1622cc) a late MGB or BMC 1800cc 5 main engine can be adapted by utilizing modified back plate to take the rear main seal.. you can fit any number of different 4 cylinder engines and boxes in the MGA and well as some of the narrower V6s... a 1600 twin cam toyota from 80-90s is a good choice.. car will likely retain more value with the 'correct as original' parts though..

aussielaurie Avatar
aussielaurie Laurie HOUGHTON
Adelaide, Adelaide South Australia, Australia   AUS
Magnas B. I agree with Timothy about the Rover V8 and MGA Gear box, I do know a chap in Tasmania ( South of Australia, look it up on Google maps ) who runs an MG business and has installed a Rover V8 into an MGA but used a Japanese gearbox, Toyota Supra 5 speed. that many of them used here in Australia they are now hard to get, Not an easy conversion but the result is spectacular. The Borg Warner T5 is the best option however they are a tall box and would need some serious mods in the cockpit area. best of luck.

freeborne Avatar
freeborne Jim Welch
Kehi, HI, USA   USA
1967 MG Midget MkIV "Spinner"
1972 MG MGB GT "Oo7"
1980 MG MGB "White Lighting"
whats the most affordable way to compeat with mg and not loose to a miata ?

rpierce Avatar
rpierce Russell P
Warner Robins, GA, USA   USA
1964 Triumph Spitfire MkII "Macau/ Kastner Tribute"
Hey guys, just reaching out here to see if anyone has experience in swapping out the MGA to a 215 V8 and what is involved. Two years ago I build a tribute car to the Triumph LaMans racer known as the Macau running the 2.0 GT6 engine with triple Webers. At the risk of being disowned I think I want to venture into building a MGA car with similar features but run the Buick/Rover V8.
Anyone with advice on what to expect or difficulties on this would be appreciated.


tjt77 timothy Trevithick
Grass Valley, CA, USA   USA
perhaps a more accurate description to 'tribute' (commonly used for 'performers' who copy the work of others to earn a buck ) would be 'Insult'.
whilst its possible to fit any engine in any car if you have the time, funding and ability, the MGA is rather tight under the hood and not really suitable for a wide or V configuration engine without hacking the chassis.. not much air flow under there either.. keeping a stock engine cool enough when the rad is old and cyl block has crud build up is a common problem..
having said that, it can and has been done.. but it not by any means 'straigforward' and there are far better routes to take.

If you desire to build hot rod MG, the MGB does lend itself well to various engine transplants and for those who want to keep with the spirit of 'period correct' a good choice is the rover/buick alloy engine.. post 74 cars are easier to convert due to the modified inner fenders designed for the rover 'block hugger' headers.. post 76 cars easier due to the forward mounted rad.. plenty of unwanted ones out there for virtually jack.. some people will pay you to take them away..
The T series cars are also more suitable to adapt to other power trains too.. and given they have what may be best be described as 'mediocre' performance with the stock running gear its actually good idea to fit something that will give em enough pep tp keep up with your average mail carriers rig..

Floridacarbuff Avatar
Floridacarbuff Silver Member Earl Chrysler
Cape Coral, FL, USA   USA
1939 Graham Model 116 "Mako"
1959 MG MGA 1500 Coupe "Le Coupe"
Hi Tim -

Regarding the selection of an "A" versus a "B" for increasing performance, first let me address the 'appearance' variable.

To me, the MGA, especially the coupe, was one of the sharpest looking 'affordable' sports cars to come out of the UK. The long, smoothly blending lines of the front fenders give the car an 'in motion' look even when parked.

Again, to me, the MGB has all of the classical lines, 'personality' and attractiveness of a bar of Ivory soap.

Moving on to the modification of the power-plant, I prowled wrecking yards with tape measure in hand. Upon reading about the apparent search by GM for a less bulky V-type engine I discovered that in 1979 they introduced the 60 degree V-6. Applying my introductory plane geometry revealed the width of the 60 degree cylinder angle block would be significantly narrower than a 90 degree cylinder angle block. My tape measure confirmed that a 60 degree cylinder angle block would fit quite comfortably within the confines of an MGA under-hood area while adding a few orders of magnitude of power beyond the 78.5 of a stock four-banger.

Also, accessory manufacturers have responded with such handy up-grades as Edelbrock's Torker intake manifold and matching Holley 390 CFM four barrel carburetor.

Given the GM engine, mating it to a 4L60 GM automatic and a 3.43 GM Posi differential is pretty straight-forward. The only 'modification' in that area is narrowing the rear axle to have the tread of the MGA and changing to wheels with the U.S. wheel bolt pattern. By the way, the U.S. trailer industry some years ago agreed to a 'standard' wheel with a bolt pattern that fits and that looks very similar to the MGA disk wheel pattern.


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