Planning an MGB V8

Planning an MGB V8

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geoffbeaumont

Original Poster:

2 posts

199 months

Thursday 13th March 2008
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First post, so I guess I should start with an introduction. I've been tinkering with Land Rovers for the last few years (my usual patch is the LR4x4 forums), but I've never owned a classic sports car of any kind. I currently drive a 300Tdi Discovery, but it's frankly rather dull and is costing me a fortune in diesel, so I'm of a mind to swop if for a small eurobox for commuting, then look for a project that I can work on in a warm dry garage (unlike a Land Rover).

I was toying with the idea of a Midget, but I have a stripped down RV8 in the loft which I want to rebuild, so something that I can put that in seems like a good move. There are lots of cars I'd like, but being realistic about what I can afford to spend on this an MG B looks like clear favourite. I'm undecided over whether to go for a roadster or GT - I like the GTs looks better, but top down motoring appeals. Maybe a GT with a webasto sunroof?

It'll be at least the back end of this year before I'm actually looking at buying anything (small matters of a wedding and house sale to sort out first!), so I've plenty of time to research what I want.

How much power is too much? The V8 I have is a 3.9 out of a Range Rover, which I was planning to rebuild as something a bit more exciting. I'm guessing even a fairly standard 3.9 with say a mild fast road cam would make for a quick B? Given that I want to finish up with a drivable car not a lethal track-only drag racer. How much power/torque can an otherwise standard car handle before it gets unpleasant or breaks things? What about with modified brakes and suspension? Either way it'll be EFI and disributorless ignition managed by a Megasquirt.

What's the best gearbox choice with the V8? If I tweak the 3.9 will a standard gearbox and overdrive take it? What about say an R380? Will it fit? Is it available with appropriate gear ratios for a B? Is it possible to make the clutch less agricultural than it is in a Land Rover?

How difficult and expensive is converting a rubber bumper car to chrome bumper? I don't like the RBs looks, so I definitely want to finish up with chrome - should I buy chrome to start with, or not worry too much about it? I know that most chrome bumper cars will make fitting the V8 more work, and I'm planning to get a car that needs a fair bit of work anyway - I'm happy to rescue a tired car and modify it, but I don't want to hack around a pristine genuine one.

Think I need to visit show or two and have a look at other peoples cars smile

TIA,
Geoff

wadgebeast

3,856 posts

217 months

Friday 14th March 2008
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I can answer some but not all of your query having looked at doing the same thing!

1) You ideally need to start with a rubber bumper car - this means that you don't need to muck about with the cross member trying to get sufficient clearance and it also means that the engine mounts are already in the right place, simplifying the whole thing somewhat.

2) There are Bs around with 300 bhp +, so the chassis can handle it although most people with 180 bhp + tend to go for some sort of independant rear suspension set up, which is costly. I had parabolic leaf springs on mine at the back with koni shocks and it transformed the car without being stupidly expensive. You will need to uprate the brakes funnily enough, but decent disks and calipers are not actually too bad for cost.

3) The gearbox will fit, although you'll have to change the propshaft for one that will take the torque. Alterations will need to be made to the footwells to allow for the broader box, which is a bit of an intrusion.

4) The RV8 I drove had a relatively light clutch, only marginally heavier than a B. Definitely better than a land rover, but I don't know what the set up was.

5) The Bee Hive in cambridgeshire sell the chrome bumper conversion kit. It's not too bad to fit, although the bumpers can be a bloody mare. There are extra bits to weld in both front and rear and therefore you need to be pretty good with an angle grinder.

There is a book entitled 'How to give your MG B V8 power' which is pretty definitive on all matters.

wildoliver

8,958 posts

222 months

Friday 14th March 2008
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Well we do quite a few conversions of this kind, as well as a good few restorations.

The rover v8 is a fairly well documented installation in to the b, there is a how to on one of the websites, I think it is MG org or something similar.

I would start with rubber bumper as suggested, to be honest I like rubber bumper cars, and try to advise them wherever possible, they offer the last incarnation of improvements to the breed, so you get better electrics, build quality, rear anti roll bar, lot's of little modifications that just make a more practical car.

I currently have a GT for sale that would be an ideal base for the project you want. I also have a GT Rolling shell that has a webasto and is 90% finished AND has been converted to chrome bumper. And I have a roadster.

Without wanting to tout for business I can sell all these cars as going concerns, or as fully finished projects, but the GT car for sale would be ideal for you, it has mot, is totally solid and is a lovely car, black leather and brooklands green. I would advise you to buy a car and run it for a while before deciding which way to go. More projects get started than finished!

geoffbeaumont

Original Poster:

2 posts

199 months

Friday 14th March 2008
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Thanks smile

That was pretty much the impression I'd got - I'm not scared of taking on a project, tinkering with Land Rovers has taught me that all jobs are at least ten time the work you anticipated, but I enjoy it and I don't mind if it takes a couple of years to get it on the road. The angle grinder is loaded and ready, but I still need to learn to use the welder I bought last year.

I'd actually rather not buy a largely finished project, as I enjoy working on the vehicle just as much as driving it. That's half the reason I'm bored of the Discovery - I've already done pretty much everything I'm prepared to do to a daily driver.

Sounds like converting an RB is probably the way to go.

IIRC the book power of the Land Rover 3.9V8 is 193bhp, so even if I rebuild it as stock I should have around that. However, as my engine is completely stripped down it would cost relatively little time and money to modestly improve on this - hence asking how much is too much!

When you say the gearbox will fit, do you mean an R380? Are there any other gearboxes I should be considering?

What are the costs involved in switching to parabolics and telescopic dampers versus a full coil conversion (which I presume is what you mean by independent - or do you mean getting rid of the beam axle, which does seem a bit of a serious undertaking?!)?

wildoliver - I'll bear that in mind, but I won't be in the market for a few months.

Geoff