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Where to start with a MGB V8 rebuild
Shantung Black Tiger - 5/10/07 at 12:13 PM

Over the last couple of years I’ve been rebuilding a Fiesta 1.1 into a 1.6 track day car (see www.BlackTigerRacing.co.uk). Now that’s nearly done I’m looking for my next project. The fiesta will still be kept as a track car / run-a-bout for my girlfriend, as it costs nothing to run and is quite fun, but I’m ready to move onto something a bit more serious having cut my teeth on a basic rebuild.

After bit of consideration I’ve decided on getting an MGB and performing a V8 conversion on it, along with building it into a Sebring replica (similar to this chap.. http://www.mgbv8.co.uk/finished.htm only without the independent Jaguar suspension) .

I’m at the “working out what I need to do and figuring out approximate costs” stage now. There seems to be plenty of people offering help and advice on the web, although I still have a few blanks to fill in.

My basic plan is to do the conversion in three ish stages. Firstly source a MGB GT (rubber bumper model) and get the shell back into showroom condition… e.g. get every tiny bit of rust out of it and under seal it all up nicely. This will give me some good opportunities to perfect my MIG welding too.

Once I’m happy that the shell is sorted I’ll be moving onto brakes and suspension. A lowering kit (new springs ... coils front and new leafs rear) and some adjustable gas shocks will replace the old style dampers. Along with the addition of a front anti roll bar and some V8 style anti-tramp bars on the back to tighten things up some more.
My question here is, will this be enough? I know that this is pretty much the setup of the original factory V8’s (plus modern dampers) however with a 3.9 ltr engine tuned to say 250 bhp (ish) will they be strong enough assuming the prop shaft and drive shafts hold, to not twist with the torque?
Second question is regards breaks. I’m planning on getting hold of some reconditioned SD1 vented 4 pots for the front, with the car only weighing 900kg I’m hoping these will cope at speed. Are any more modern breaks, rover 600’s / ZS180 units that would fit?

The final part of stage two will be to add on the Sebring kit i.e. flared arches and front/rear valances. This will then enable me to put on some nice alloys with plenty of rubber for added grip.

All this will then lead to the final stage, dumping in a 3.9 rover V8, along with the rigmarole of adjusting gear box cross member and making a few adjustments to the transmission tunnel. I’m hoping to be fitting an SD1 5 speed gear box off a V8. Improvements to the diff (new crown and pinion) and replacement prop shaft too. Question here is again will this be enough???

Once the engine is in then some mid level tuning will be done. 270 cams, either up rated injection or a holly/Edelbrook 4 barrel carb and maybe some basic porting and gas flowing of the heads. All this will be well down the line though.

So as it stands I can figure out rough costs of the first stage, basic restoration and to be fair this will take a good 6 months of my time anyway. I want to have a good idea of weather my plans for the suspension and brake updates I have in mind are going to be up to the job too. I can “roughly” price these up and know what I have mentioned above is financially doable for me. Fitting the Sebring and V8 engine can be done in 2 – 3 years time if needs be, so long as I’m confident that the chassis I have prepared is up to the job in the first place.

So essentially what I’d like before I start is maybe one or two chaps to say.. oh yes what you’re saying is close to what’s been done before and should work., or don’t be daft that’ll fall apart as soon as you touch the power.

Just to note: at the end of each stage I won’t be rebuilding and putting it back on the road, just that I'll have the option to if there was a change of circumstances. But in essence I will strip the GT shell down, remove the rust and re-spray it, (having kept all the original running gear just in case). Then buy the new suspension and brakes parts and fit them to the restored shell, followed by fitment of the engine and improved prop/diff lastly. The idea of doing things in stages was simply to give me bail out points if I run out of money really.

Thanks for taking the time to read through.

Any comments, ideas or suggestions welcome. Including better ways of doing the suspension.. E.g. possible kit car applications for rear wishbone conversions that might be an option, or other V8’s … Simon has already suggested the Chevy LS1, but it’s a bit pricey for my buget.


BenB - 5/10/07 at 12:15 PM

Can you get a new Heritage MGB chassis?
Not a cheap option but it can speed up the build!!!
They look very nice


jambojeef - 5/10/07 at 12:25 PM

Why not just buy an MGRv8?


britishtrident - 5/10/07 at 12:32 PM

Hertitage shell

With the B you can get a LOT of hidden rust.


Paul TigerB6 - 5/10/07 at 12:41 PM

This should help http://www.mgcars.org.uk/v8_conversions/rogv8.html

I considered doing an MGB roadster V8 myself before i built my first Tiger kit. My previous toy was a 1968 MG midget


Shantung Black Tiger - 5/10/07 at 12:42 PM

I've had a look at the Heratage shells, well online anyways, but I'd be looking at 5 grand outlay to begin with. A decent MGB and parts to refurb and strengthen it I believe will be half that cost. I'm planning on doing all the work myself, and am not too bothered on the time scale. Hopefully carful selection of my starting car will ensure I don't have one with rusted out A-pillars or too much welding to do.

I considered buying a MGB-V8 straight off, but then half the fun of converting a standard one is to say I did it myself.


Shantung Black Tiger - 5/10/07 at 12:45 PM

quote:
Originally posted by Paul TigerB6
This should help http://www.mgcars.org.uk/v8_conversions/rogv8.html

I considered doing an MGB roadster V8 myself before i built my first Tiger kit. My previous toy was a 1968 MG midget


Thanks, I read through that just yesterday. Very informative.

Seems to imply that the standard suspension set up from a factory V8 is sufficent, but thats on a standard 3.5 (165bhp), I'm wanting to fit a 3.9 tuned to (250bhp) and am not sure it'll be enough to just copy the factory V8 setup.


MikeRJ - 5/10/07 at 12:48 PM

The standard 3.9:1 rear axle ratio is way too high for a V8. You need to start looking for a V8 axle which is around 3:1 IIRC.


Paul TigerB6 - 5/10/07 at 12:53 PM

How about this from within our kitcar industry then??

http://www.hawkcars.co.uk/parts/mgbsuspension/mgbsusp.html


Paul TigerB6 - 5/10/07 at 01:00 PM

quote:
Originally posted by Paul TigerB6
How about this from within our kitcar industry then??

http://www.hawkcars.co.uk/parts/mgbsuspension/mgbsusp.html


better pics if you click into Hoyle engineering's own site bottom right. Not cheap though!!!


Shantung Black Tiger - 5/10/07 at 01:11 PM

quote:
Originally posted by Paul TigerB6
quote:
Originally posted by Paul TigerB6
How about this from within our kitcar industry then??

http://www.hawkcars.co.uk/parts/mgbsuspension/mgbsusp.html


better pics if you click into Hoyle engineering's own site bottom right. Not cheap though!!!


ooh.. that looks perfect, right up until I saw the price. grrr. Maybe if I start saving now, by the time I finish getting all the rust out of the shell i get then I will be able to afford the rear suspension setup.


02GF74 - 5/10/07 at 01:16 PM

I useda have an MGB, 72 roadseter so kinda took an interest in this.

you are right with starting with the post 73 models - rubber bumper since htey have the engine bay reshaped to allow for hte v8. ofcrouse these are not as nice as the chrome bumper, plus cb are lower - but you can reshape t he engine bay to practise your welding.

I seem to remember ther was some work needed to the front cross member - or was that for a V12 conversion?

regarding the piece wise cnversion - make sure when you do the suspensio that is is v8 compatible; pretty sure it is but you don't want to be doing it/spending money twice.

only other think I can add is the carb - there was a special one made for this aplication to keep the bonnet flat.

maybe efi will fit without bonnet mods?


Shantung Black Tiger - 5/10/07 at 01:24 PM

quote:
Originally posted by 02GF74
I useda have an MGB, 72 roadseter so kinda took an interest in this.

you are right with starting with the post 73 models - rubber bumper since htey have the engine bay reshaped to allow for hte v8. ofcrouse these are not as nice as the chrome bumper, plus cb are lower - but you can reshape t he engine bay to practise your welding.

I seem to remember ther was some work needed to the front cross member - or was that for a V12 conversion?

regarding the piece wise cnversion - make sure when you do the suspensio that is is v8 compatible; pretty sure it is but you don't want to be doing it/spending money twice.

only other think I can add is the carb - there was a special one made for this aplication to keep the bonnet flat.

maybe efi will fit without bonnet mods?


Yes I think I read that you need to make alterations to the cb engine bay to get the V8 in. The cb are lower, but as I'm rebuilding the suspension one way or another then the ease of mounting the engine takes priority. Sebring front and rear valences mean that asthetically there will be little difference in the end if I start chrome or rubber.

I'm not too fussed about a "little" bonnet scoop to accomodate a nice carb, but I believe the EFi units fit under the MGB bonnet anyway.

Hopefully with the right preperation and research before I start then I will only need to do each job once ... correctly. My old man is a carpenter, the amount of times he's said, measure twice cut once must have eventually sunk i.


stevec - 5/10/07 at 01:47 PM

Why not get the estate version? Probably a bit cheaper.

MGB estate


britishtrident - 5/10/07 at 02:24 PM

I think you perhaps need to take a few reality pills, £5100 for a new shell isn't that much when you consider the cost, time & effort required to repair a B with the castle sections rusted out. Unless you have owned a similar vehicle you can have no idea how much rust you will encounter.

You have also got to consider the difference in resale value. Car built on a hertiage shell will be a lot easier to sell attract a big premium over a collection of welded up panels.

Also if you do start tacking on body kits and arches you will drastically reduce the resale value.

Concentrate on producing as near perfect a standard looking car as possible.

Also with a B at chrome bumper ride height the handling isn't that shabby once the roll stiffness is increased (particulrlyat the rear).
Also wedges between the front crossmember and the body to reduce the caster angle to make the steering lighter and more suited to modern tyres.


will121 - 5/10/07 at 02:33 PM

i looked at doing it, there was a full right up on what you are thinking of doing in a mag possibly CCC a couple of years ago including the body kit and wheels, i think ive still got a copy of it somewhere. if of use can copy and post, or il try and find some one with a scanner!


Paul TigerB6 - 5/10/07 at 02:56 PM

quote:
Originally posted by britishtrident
I think you perhaps need to take a few reality pills, £5100 for a new shell isn't that much when you consider the cost, time & effort required to repair a B with the castle sections rusted out. Unless you have owned a similar vehicle you can have no idea how much rust you will encounter.

You have also got to consider the difference in resale value. Car built on a hertiage shell will be a lot easier to sell attract a big premium over a collection of welded up panels.

Also if you do start tacking on body kits and arches you will drastically reduce the resale value.

Concentrate on producing as near perfect a standard looking car as possible.

Also with a B at chrome bumper ride height the handling isn't that shabby once the roll stiffness is increased (particulrlyat the rear).
Also wedges between the front crossmember and the body to reduce the caster angle to make the steering lighter and more suited to modern tyres.



Thing is though that he has a specific car in mind that he wants to end up with - a Sebring version with a V8 fitted and uprating to handle the 250bhp planned. I'm sure thats why the post is on LocostBuilders rather than the MG forums - because one thing i guess all us kit builders do is do things how we want them to be and so there's a huge amount of knowledge to call on.

Restoring the body shell is surely down to the skill of the builder - and also can be the most enjoyable part of the restoration for many classic owners (I was in the MGOC for years) so a Heritage shell isnt always strictly the best option. There are so many repair sections for MG's available and time isnt an issue (but the wish to say "I built that" might be there)

I personally would think a Sebring replica would sell very well - but then again how many of us build our kits worrying about if it will sell (unless its those builders who do it with the intention of a quick sale post SVA and then start on the next).

Go for it I say

[Edited on 5/10/07 by Paul TigerB6]


MG David - 5/10/07 at 03:14 PM

On the shell prep front you could reduce the work and time by sending the shell from you chosen car to Surface Processing in Dudley for it to be dipped.

On the rubber vs chrome shell, if its rubber you want it to be late rubber not early rubber as the early rubber shells did not have all the V8 features. Having said that if you use RV8 style exhaust manifolds you do not need the V8 inner wing extra dishes, just the forward rad and bulkhead mods.

The SD1 gearbox, also called LT77, requires a mod to the trans tunnel. There is a Toyota box, the W154, which does not need this but it either needs a home made adaptor plate or a bell housing from Dellow in Australia £££.

As far as the back suspension is concerned. I think you will want to add a panard rod. They can be made following the locost method of looking at one commercially available and copying it!


For more sophisticated DIY live axle suspension mods try the following site:-
http://www.vord.net/cars/mgb_mods/updates.html

Also the Frontline Costello rear coil over 5 link kit may provide some ideas.

For further ideas another site to try would be: www.britishv8.org


ned - 5/10/07 at 04:28 PM

re different engines how about a modern bmw unit out of a 5 series with a manual box. just watch out for the ones with nicasil liner issues.

Ned.


MG David - 5/10/07 at 04:30 PM

Modern DOHC per bank V8s tend to be a bit too wide for the MGB engine bay. However, a modern 60degree V6 would be very good. Is the Jaguar/Ford 3L duretec a 60 degree? I know some V6s are 90 degree these days.


caber - 5/10/07 at 04:34 PM

I would also suggest starting with a heritage shell. The acid dip and phosphate route will cost almost the same. Going this route woulld alow you to buy basically a scrap MG and retain its registration with V5 changes for colour and engine as required. If you get some of the salvage auction lists you can get a doner for very little. I thing Practical classics or the other simmilar magazine have ben running a series on this sort of thing recently though I suspect you want something a bit more radical. Classic cars current issue has an article on the 6 pot sebring cars built with aluminium exterior panels there are a few pictures in there of interest.

I really would avoid a cheap rust bucket as a shell doner you will in the end regret it. I am helping a friend with a Triumph herald that was fully restored 5 years ago by a pro company, braised shell repairs waxoyl and all, in that time rust has reappeared around some pof the brazed repairs, some replacement pattern panels have rusted out so we are doing a lot of work again. This car has lived outside since restoration and been used as a daily driver for most of that time but still I would find it very annoying to have to redo my own work after that kind of time!

Caber


Fatgadget - 5/10/07 at 05:29 PM

quote:
Originally posted by BenB
Can you get a new Heritage MGB chassis?
Not a cheap option but it can speed up the build!!!
They look very nice


I thought you had to prove you had a donor MGB before Heritage sold you one of their new body shells?


paulf - 5/10/07 at 05:47 PM

Ive got a 1970 chrome bumper BGT that I need to get out of my way .It is tax exempt but does need a re shell , has tidy chrome etc and has overdrive and wire wheels.
I have owned it since 1983 and kept meaning to rebuild it and put it back on the road but can never find the time and money to do so.
Paul.


Shantung Black Tiger - 5/10/07 at 07:46 PM

I'd love to start with a heratage shell,
but to be honest I really don't have £5000 to outlay at the beginning of the project. One thing I do have is lots of time and determination, some spraying experience and can weld a bit.

I'm quite happy to bide my time and choose a donor car that hasnt got too much rusting to deal with and take it from there. I am aware also of the potential amounts of hidden rust I may come into contact with too. But I'm just gonna have to the best I can with what I have when the time comes. I'm not planning on starting from a total rust bucket

I've just had an email off a chap from my usual forum (my regular car is an MG ZS180, and I post on xpowerforums.com) who runs a standard MGBV8. Well I say standard.. the rear suspension, wheel hubs brakes and half shafts are standard with just uprated prop and diff. Front brakes are MGB-V8's with competition pads and disks. The engine though dyno'd at 187hp at the fly NASP, and 257hp at the fly with a 50 shot of gas. He's run this on 1/4 miles regularly with no issues at all. In short his advice was....

"So to summarise, shove the V8 in, make the running gear standard V8 spec and you wont go far wrong for a road use and sprinting. If you want a well handling circuit car, go for IRS and a coilover setup on the front."

With this in mind I think I'll plan to do my best to get the most out of the standard MGB setup... lowering kit, new springs and leaf's and uprated dampers, couplled with arb's and anti tramp bars.


DavidM - 5/10/07 at 08:57 PM

quote:
Originally posted by stevec
Why not get the estate version? Probably a bit cheaper.

MGB estate


'kin excellent!

David


x_flow57 - 5/10/07 at 09:34 PM

Don't forget to bare in mind the rubber bumper cars raised ride height was acheived by modifications to the body and front x-member, not just different springs. If you fit lowered springs and it will eat tyres.
Nick

<<<<< For Sale

[Edited on 5/10/07 by x_flow57]


DIY Si - 5/10/07 at 09:42 PM

Would a late chrome bumper do you? I happen to have a late 73 version sat outside my house looking for a new home. It is starting to go around the rear wing tops though. Otherwise I don't think there's much rust elsewhere, although it is a classic car, so I could be wrong!
Sounds like an interesting project, a bit different to the usual K series conversions! Are you planning on doing anything with it? Hillclimbs, trackdays etc?


Shantung Black Tiger - 5/10/07 at 10:08 PM

quote:
Originally posted by DIY Si
Would a late chrome bumper do you? I happen to have a late 73 version sat outside my house looking for a new home. It is starting to go around the rear wing tops though. Otherwise I don't think there's much rust elsewhere, although it is a classic car, so I could be wrong!
Sounds like an interesting project, a bit different to the usual K series conversions! Are you planning on doing anything with it? Hillclimbs, trackdays etc?


Hmmm, tempting... any pics? Is it tax exempt? Surface rust or rust on the outer shell/pannels isnt a worry. I'd just be put off by rust in the A-pillars and main chassis, oh and the castle sections too as Trident pointed out. Pannels sills and floor pannels I can cope with... welding up the main structure is another story, especially if I'm putting V8 torque throught the lenght of the car too.

The car in the end will be mainly for a bit of weekend fun and maybe a bit of drag racing, not really going to be doing too many circuit track days though as I have my ZS which will blow it out of the water for handling and my little fiesta that I can thrash about without too many worries.


DIY Si - 6/10/07 at 01:14 PM

Annoyingly it's not tax exempt, it was made in early '73, but registered as a 73-74 plate. The heritage people said it was made in the first part of the year. It is a not so fetching orange/red colour though, Blaze Orange officially. There's a couple of pics in my archive. I can take some more if you wish. Oh, may be best to do the rest through U2U to leave this thread for the build stuff, if you're interested that is!


Simon - 6/10/07 at 09:01 PM

SBT,

Hello. Can't think how you possibly found this site

Oh yeah, and welcome!

Re the Hoyle IRS, I reckon you could go to any of the kitcar manufacturers doing 7's with Sierra IRS and ask if you can buy a 1/3rd of a chassis (ie the bit you need), then modify to fit. Cost about £300 including bones etc

ATB

Simon

[Edited on 6/10/07 by Simon]


Shantung Black Tiger - 7/10/07 at 09:27 AM

quote:
Originally posted by Simon
SBT,

Hello. Can't think how you possibly found this site

Oh yeah, and welcome!

Re the Hoyle IRS, I reckon you could go to any of the kitcar manufacturers doing 7's with Sierra IRS and ask if you can buy a 1/3rd of a chassis (ie the bit you need), then modify to fit. Cost about £300 including bones etc

ATB

Simon

[Edited on 6/10/07 by Simon]


I think Ill have a good few months of shell restoration to do before I begin looking at suspension setups, so fingers crossed I can find something suitable. If I can get an IRS setup thats affordable and not a complete refabrication from a donor car, then I'll go for it. If not then I'll get the best setup I can from the standard MGB.

oh and thanks for pointing me in the direction of this forum, seems theres lots of people with lots of ideas... which is what I need.


02GF74 - 8/10/07 at 09:57 AM

quote:
Originally posted by DIY Si
Annoyingly it's not tax exempt, it was made in early '73, but registered as a 73-74 plate.



unless someone corrects me tax exemption goes according to date of manufacture not registration; I think thje date is 1 Jan 1973.

You can, or could about 10 yrs ago, just about buy any part of the shell.

If you can use a grinder and are a competant welder then you should have no problem replacing panels.

obviously you should be familiar with the car or take someone who knows them so you don't buy one will filler and take away tray for sills (don't even ask me abpout that :mad

I replaced the sills, rear quarter wings, the box section inside the front wings no probs and had no welding experience.

it is all doable but when dealing with a roadset, you would need to jig it so that is does no fold when replacing sills (one at a time obviously).


DIY Si - 8/10/07 at 03:32 PM

You are indeed correct about the date of manufacture, hence why I say it's a 73-74 plate (old M plate), but didn't quite get made early enough. IIRC it misses by a couple of months.


Shantung Black Tiger - 29/10/07 at 12:49 PM

well I eventually found myself a suitable MGB as a start point. Slightly tired interior and paintwork is average, but on the plus side all the welding has recently been done including the castle sections by an approved MGOC garage... recipts to prove it

So basically a few touch ups and maybe re-doing the underseal and I can get going on the running gear by christmas. Woo!!!

It came with new alloys and tyres too, worth over half what I paid for the car along with 12 months tax and test. Engine is very smooth too... which is good from a selling on point when it is replaced by the V8.

All I need to do now is save up for all the bits I'm going to need to do the conversion.

[Edited on 29/10/07 by Shantung Black Tiger] Rescued attachment 8e70_4.jpg
Rescued attachment 8e70_4.jpg


Shantung Black Tiger - 29/10/07 at 12:51 PM

And a quick picture of the underside too... Rescued attachment 8e60_4.jpg
Rescued attachment 8e60_4.jpg


Simon - 30/10/07 at 01:32 AM

Looks like you got quite a good basis for a project. Was gonna say rebuild, but think re-engineer is more appropriate

First job, remove everything you don't need/want and sell. That can go straight into the mods kitty

Keep us posted

ATB

Simon