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MG MGB GT V8 Factory Originals Technical - Improving a factory V8
I would consider bumping the compression up to 9.35:1 or 9.75:1, the factory cars had a rather agricultural 8.25:1, and you can still run on pump gas. According to Rover, the engines were supplied new with hardened valve seats, so you shouldn't have to worry about the lack of lead. A full engine balance is also a good idea when you have it torn apart.
In a few months, I will report on the effectiveness of those two modifications (when my car is reassembled, I just got the finished bodyshell back on Saturday!)
1974 Factory MGB-GT V-8 (The Phoenix, formerly The Rustbucket)
|Fit neg camber wishbones. Fit 30% uprated Armstrongs front and rear.- not teles. Fit uprated and lowered front springs, or better still, fit a set of one inch lowered stub axles, and uprated standard height springs.|
Fit a set of Minilite lookalike wheels, 6JX14 and 4xGoodyear Eagle F1's in 195/60 size. Fit RV8 manifolds and a decent exhaust. Fit uprated alternator, headlight relays and halogen bulbs. Will that do you?
|Are these 'improvements' for driveability, looks, or as an engineering hobby exercise ? Only I would have thought for the number of miles the average factory V8 does per year they were almost all a bit of a waste of effort (except the rustproofing, decent tyres and decent lights).|
The improvements are aimed at making the V8 easier to live with as an only car. I travel to work by public transport, so it's a weekend car really, but I managed to do 30k miles in 4 yrs in my old V8. I'm a mechaniacal engineer by training so all the stuff I suggested above is sort of hobby stuff but does make a big improvement to the factory car for modern driving. I'd really like to add aircon for use in summer London traffic but from what I've heard about the RV8 installation it's quite intrusive into the passenger space. Any thoughts anyone? does anyone know of a small condensor unit that could fit into the glovebox space?
I have a factory CB V8 which has travelled about 40.000 km during the last two years.. I think I may call it a rolling restoration.
I bought the car almost completely factory spec.
The car already had a standard Lumenition ignition, a modification I would have done anyway.
The previous owner also hat changed the front springs to Pirelli Competition spec, and lowered the rear springs.
The car had a Spax telescopic damper conversion on the rear, which I somehow disliked because of the tendency of the adjustment screw's threads to get lost.
Then I did the following mods ( not all at once, of course):
Changed all the bushes from rubber to SuperFlex. I mean all, even the Anti Roll Bar's.
Changed the ARB to 3/4.
Changed the front lever damper inserts to stiffer ones.
Changed from Spax to Koni. Expensive, a bit cumbersome (dampers may only be adjusted out of the car), but what a difference...
Changed the front springs to AHT 21.
Changed the wheels to KN Minilite replicas 5 1/2x15.
Changed the tyres to Goodrich 185/65HR15.
This will result in a much more direct road contact (with more dynamic stress on the suspension, of course!) while retaining the original rolling diameter, so no need to recalibrate anything.
I fitted the bigger front brake pads (Mintex).
I left the engine completely alone, because I think the suspension and power transfer is the weak point of the car.
I tried it on the Nürburgring-Nordschleife for several days in summer 99. Tyre pressure was about 2.0 to 2.1 bar all round, sometimes modified.
The car handled exceptionally well, mostly neutral, sometimes even too neutral, so I tried to tried to get some oversteer through tyre pressure because of the stiffer ARB. As always with us amateurs, I had to stop before getting wise. The engine mountings broke!
Changed all engine mountings.
They broke again during a (rather tame) Rallye 5 months later. Including the gearbox mountings, this time.
And including the gearbox!
- the gearbox is out and will be exchanged against a new old unit
- engine will be dismantled, inspected, balanced and hopefully not too much repaired
- engine mounts will be exchanged against Jaguar XJ6 ones. No experience yet, some modification to the original parts will have to be done (studs on both sides).
- I am thinking of fitting an engine stay to the alternator mountings.
I will NOT do anything more dramatic to the car, because I want to use it for historic rallying, where original appearance is part of the fun.
In conclusion, I would say it is not the question of getting the most power out of the ole V8 - this is comparatively easy, and I would like to do that on a GT Special, some time.
It's the weak suspension one has to work on. And the lack of a limited diff, if one stays original. And the total lack of downforce at 150 Km/h+. But I think that aftermarket spoilers are out of place on a CB V8...
sounds a balanced set of mods IMO, I too like originality without being a slave to it. What sort of times did you do at the Nordschleife ? (I am planning to go there later this year).
|Having just done LE JOG - Lands End to John O Groats - total mileage 2450 in six days - essentials for improvements are:|
The best rear shockers you can get / possibly new leaf springs - use heavy duty they improve the car considerably.
improve cooling for summer - new radiator ( aliminium one)
konis on front
This thread was discussed between 07/02/2000 and 13/02/2000
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