Newby with a V8 project

3xpendable · Post by **3xpendable** » Tue Feb 16, 2010 8:46 pm

Hi All,

I'm a newby to this site but I currently have an MGB GT 1800, i've sourced a V8 spec shell so plan to convert it as and when I get the time. See the pics attached of the shell, I also got an engine for it which is the desirable short nose model for the MGB/Rover P6, but alas when I stripped it two of the bores were rusted out, and a hone didnt clear it so i'm looking for a new motor!

Enjoy

CastleMGBV8 · Post by **CastleMGBV8** » Wed Feb 17, 2010 12:41 am

Welshie,

Welcome to the forum there are few MGBV8 nuts on here including me and a certain Mr. Stephenson with a very rapid 4.6 nitrous injected drag race car amongst others.

Looks a decent shell to stqrt off with but if you bought it in primer and it's been that way for a while you really ought to strip it back to bare metal as most primers are absorbent and rust will be present underneath!

The P6 engine looks pretty much scrap and your not missing a lot apart from some cash as the P6 is not a particularly good engine to base the conversion on.

The only benefit of the P6 was the shorter front cover, water pump arrangement, you can use the later SD1 cover which has the later neoprane oil seal and still use the p6 water pump, and higher volume oil pump

Save what you can off the P6 engine you will need the front crank pulley, flywheel and the alternator cradle/bracket and the alternator itself if in working order.

There are quite a few 3.9 bare or full engines around these days and with a light rebuild and some sensible mods can perform very well without getting into big money.

You don't say what you intend using the car for and this is important when asking advice as to modifications.

For conversion parts at sensible prices Dave Vale at V8 Conversions in Farnborough Kent is hard to beat TEL. 01689 858716 He has the correct engine mounting brackets and conversion bracket for the gearbox crossmember for the LT77 gearbox + anything esle you need to do the conversion.

MGB Hive are also good for parts and do very good MGRV8 through the inner wings manifolds and exhaust system in stainless steel for approx £425.00 avoid block huggers if you can as they cost you power.

Also before buying stuff for conversion and upgrades ask on here as we can probably point you in the right direction and save you money.

If you want advice on suspension and brake upgrades I would be pleased to pass on the benefit of my experience of the mods on my 75GT

Good luck and have fun,

Kevin

topcatcustom · Post by **topcatcustom** » Wed Feb 17, 2010 10:39 am

Personally I'm not overkeen on the chicken wire engine bay floor pan.

But thats just me

Looks like an excellent base project! Like Kevin said, sand the primer back and start fresh, in a couple of years time you may seriously regret it if you dont for a days free work.

Engine wise- a 3.9 is a good decent power lump to start with for a good price, though if you want maximum power in the future there is no better place to start than with a 4.6. You only need the block, pistons rods and crank as the heads etc etc etc you can use off any other RV8 so you don't get tied up in getting overcharged for "4.6 heads". They are almost the same as any other late heads, just get as late stuff as you can find/afford.

You planning on going carbs or injection, dissy or electronic?

Good luck!!!

3xpendable · Post by **3xpendable** » Wed Feb 17, 2010 11:54 am

Hi Kevin,

Many thanks for that, the project is going to be slow due to other commitments and I want a decent garage for it before I complete it, but I will of course keep everyone updated and no doubt be blagging parts and information!
Yep the shell is very decent. Its a 75 rubber bumper thats been converted to chrome, basically the guy started the V8 conversion but gave up. It has all new rear springs, recon rear axle, all new front suspension and new sills. I pulled the wings off it recently and there is come minor patching to do on the inner's, and some dressing where the wing meets the scuttle but other than that its solid. Don't worry I will be bare metalling it before a rebuild as they have sprayed the primer over everything including grease in the engine bay so as you can imagine its not stuck too well!!
The P6 motor is scrap yes, however like you suggested i've kept all the short nose parts from it. I was looking for another 3.5l block but will these fit onto a 3.9 without much hassle? I'm also preferably looking at short motors as I have bought a pair of big-valve SD1 heads rebuilt and ready to fit, would these fit a 3.9 too? If so the extra 400cc might be welcome.

In answer to your question, the car is only going to be 'fast road' spec, I basically want something I can enjoy and has the grunt to have some fun when I want to. I race 250cc superkarts you see which are faster than a Bugatti Veyron, so I won't be needing to get race thrills form the B! I have a pretty good idea of the base spec I want for the car after reading 'How to convert your MGB to V8 power'

So at the moment i'm on the lookout for a short block 3.5 or 3.9 V8, and later down the line an Lt77 box. Once I get those fitted I can concentrate on the brakes, suspension & interior!

3xpendable · Post by **3xpendable** » Wed Feb 17, 2010 11:56 am

topcatproduction wrote:Personally I'm not overkeen on the chicken wire engine bay floor pan.

But thats just me

Looks like an excellent base project! Like Kevin said, sand the primer back and start fresh, in a couple of years time you may seriously regret it if you dont for a days free work.

Engine wise- a 3.9 is a good decent power lump to start with for a good price, though if you want maximum power in the future there is no better place to start than with a 4.6. You only need the block, pistons rods and crank as the heads etc etc etc you can use off any other RV8 so you don't get tied up in getting overcharged for "4.6 heads". They are almost the same as any other late heads, just get as late stuff as you can find/afford.

You planning on going carbs or injection, dissy or electronic?

Good luck!!!

Oh damn, I was hoping the chicken wire diffuser might catch on! Thanks for that. I'm looking at 3.5 or 3.9 at the moment, nothing too extravagant. I plan on carbs (holley with a pnacake filter, gotta be done) and most likely electronic ign

topcatcustom · Post by **topcatcustom** » Wed Feb 17, 2010 12:04 pm

3.9

easy bhp for a few £ extra. And yes your SD1 heads will fit no probs, they should be identical to any 3.9 ones.

The only thing to watch for if buying a short block is why have they sold it?! If they are selling the short block they may well have had slipped or cracked liner trouble hence get rid of the old block and keep the ancilleries for their replacement. Wish I'd double checked when I bought mine

just keeping my fingers crossed though

3xpendable · Post by **3xpendable** » Wed Feb 17, 2010 1:42 pm

3.9 it is then

ppyvabw · Post by **ppyvabw** » Wed Feb 17, 2010 2:19 pm

This might interest you. Quite a common occurrence. A strip and new shells etc and you'll be on to a winner.

http://cgi.ebay.co.uk/Rover-3-9-v8-engi ... 23055a69d5

ppyvabw · Post by **ppyvabw** » Wed Feb 17, 2010 2:26 pm

In fact I am looking on ebay now and there are quite a few things that might interest you if you can lay out for them all at once.

An lt77 box, a bell housing

http://cgi.ebay.co.uk/Rover-V8-Bellhous ... 439d500e66

http://cgi.ebay.co.uk/LT77-Gearbox-Rove ... 3caa219102

Be an idea to get a number for that box thought to see what ratios it has.

3xpendable · Post by **3xpendable** » Wed Feb 17, 2010 4:24 pm

Damn you ppyvabw! Seriously tempted by that engine though.....

ppyvabw · Post by **ppyvabw** » Wed Feb 17, 2010 7:20 pm

Welshie wrote:Damn you ppyvabw! Seriously tempted by that engine though.....

Sorry

CastleMGBV8 · Post by **CastleMGBV8** » Wed Feb 17, 2010 8:17 pm

Looks like that might come cheap, only two bidders and If it comes with the full EFI system it might just be a bargain at anything under £500.

Provided it's had reasonably regular oil changes the bores should be fine and a hone, re-ring and new shells including the cam bearings will get the job done.

With a decent pair of big valve heads and a good fast road cam it wil be good for 230 + BHP.

It's going to cost you around £500 for a carb and manifold + filter. anyway so go for it you'll save loads.

Keep us up to date.

For a bit of inspiration this US forum is great.

http://www.britishv8.org/British-V8-Current-Issue.htm

Kevin.

3xpendable · Post by **3xpendable** » Sat Feb 20, 2010 10:51 am

So what does a standard 3.9 put out compared to a 3.5? Reading the 'How to convert your MGB to V8 power' by Roger Williams I was originally in the 'up to 200hp' bracket for drivetrain and shell modifications, but from what you lot say the 3.9 with a better cam and carbs will put out 200-230bhp.

For this it book recommends anti tramp axle brackets etc which I am going to fit anyway, can I retain the standard front suspension etc? I know abou fitting new dampers on the rear etc.

Thanks

kiwicar · Post by **kiwicar** » Sat Feb 20, 2010 3:06 pm

Hi
A RR 3.5 is rated about 145 bhp on EFI about 135 to 140 on Strombergs/ Su's an SD1 was rated about 156. basic porting and a mildly uprated cam and headers on with either EFi or carbs 190 to 200 BHP
a 3.9 is rated at about 165 to 180bhp depending on CR and if it is flapper or hotwire (that is rated, I suspect they both actually put out about the same) stage 1/2 to 1 heads and a suitable cam will again give about 200 BHP, is assembled very well it may get and on well matched headers 210BHP but that is tops. Add an aftermarket ECU you will see the 210 when tuned right.
To get beyond that you will need very good heads and a more radical cam you may get to 220 if all manifolds are matched to the heads (not the gaskets) but you will loose bottom end.
Mike

richardpope50 · Post by **richardpope50** » Sat Feb 20, 2010 7:02 pm

What about a V8 from a TVR instead? I originally was going to get an RV8 and spend money upgrading it but then used a TVR V8 and it was all done for me. OK, in the end I got a 5.0l Griffiths for £2,000 incl gear box from a rolled car but that was far cheaper than an upgrade to the same level. Mine's a serp engine so not sure if it fits and MGB shell.

This is all currently for a Dax Rush but my next project is a V8 MGB so would be interested to know if a TVR RV8 fits in one.

Richard.