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MG MGB GT V8 Factory Originals Technical - Olds 215 to MGB 4-synch?

Caution: New kid on the block. I have an Olds 215, a 74.5 MGB/GT and a rebuilt 4-synch O/D transmission. Who makes a conversion backplate, flywheel and clutch to put this engine and transmission together? Hey, I'm 64 years old and I'm not going to dump the clutch or run the local drag strips. I think the MGB box is good enough. I'll either fix the box so it doesn't go in O/D in 3rd, or I'll promise not to use it! Plans are to use an 8" Ford rear end around 3.08:1.

I'm going to rebuild the 215 first. Any advice on what pistons or other components to use is appreciated. Healthy performance coupled with daily-driving tractibility/reliability is the goal. 180 hp/200# torque is certainly enough for this ol' guy.

Thanks anybody,

Allen Bachelder

My 79 B has the same setup except for an MGC 3.07 rear axle. The transmission should give you no trouble as long as you don't abuse it and lock out 3rd OD. Even if you do blow it up, MGB transmissions are relatively cheap to buy used or rebuild.

Don't know if the backplate is still available or not.

Good luck with your conversion.



Thanks for your quick and encouraging reply! I'd use the MGC 3.07 - but I suspect I'll have trouble finding one. Do you recall where you got your backplate?

Thanks again,
Allen Bachelder

Maybe look at the diff' last. I'm using a 3.9 rover motor & supra box and the standard '75 MGB diff.
The diff' is over engineered and way strong enough. Was orrigionaly intended for a small truck. I find that I can accellerate strongly from second gear while first gear is useful in peak hour and parking etc. After all you don't want to be sliding the clutch all the time.
If I had the 3.07 I probably couldn't do this take off from 2nd and first would still be a little low.
Best thing is to try out your std MGB diff' (which won't cost you anything) and then make up your mind. And then before the MGC, maybe look at a limited slip diff' of some kind. The Nissan skyline (I'm told, havn't comfimed this) is usful because it has the diff' offset from centre and the short side of the axle is the same length as the MGB. All you need do is have the long tube shorted and buy another "short side" axle. It's also limited slip. Much,much cheaper to do than shortening both sides AND cutting and resplining both axils.
I would suggest a different box from the std if you're planning any sort of power increase on the 135 odd BHP that the factory MGB GT made, and it soulds like you are. T5's seem to be favoured in the US and will bolt up to your engine without adaptor plates. Check out Roger Williams Book etc..

Allen--I am 63 --but like to dump the clutch--lol--I have 5.0L Ford B .
I found my T5 in a scrap yard for $75 and rebuilt it for $170--overhaul kit. Its a great tranny and well worth the money and the 5 th gear gives low rev cruising, just my 2 cents but if youre going to all that trouble enjoy a better transmission.
All the best --Gil
Gil Price

Peter, Gil,

Thanks for all the useful advice. I haven't closed my mind on the transmission choice. In fact, I have access to a late TR7 5-speed box for $100, but I'd rather not have to open up the transmission tunnel that much.

If I could find a T5 for anything close to $75, I'd buy it on the spot. I've called a lot of scrapyards - finally found one for $900. But then, I understand an external slave cylinder on the T5 involves expanding the tunnel on the passenger side, and the alternative is an internal one - which can be rather a headache, right?

Thanks agaain.

Allen Bachelder

I saw a 5.0L driveline and 5 speed trans for sale for $600 in Eugene Oregon the other day. You can get T5's cheap, and the rebuild kits aren't bad either. I have a rover 5 speed box and if the opportunity came up I'd switch to a T5. Not because the rover box is bad, but rather, because the parts market for the T5 is HUGE. You can buy brand new T5's for around $1,000 and I think Dan Lagrou sells the T5 built for an mgb, and also the bellhousing you need, and really all the other parts too. You can use a hydraulic throwout bearing, and not need a slave cylinder at all! Dan's website is

Personal recommendation is to bump the compression on the 215 to mid 9's or even the 10's if you want the extra power, but then you'll have to run 91 octane gas. (with compression in the 10.5:1 range) Use the buick 300 distributor, and a pertronix II electronic ignition. Carb: I'm not sure, I have rover fuel injection, and I'm finally starting to like it! =)

More people will chime in on carbs, and other things, but my bottom line is this: Raise the compression, get a crower 50232 cam from Dan Lagrou, and use a T5 5 speed trans. You'll be very happy you went in that direction.


p.s. use the Rv8 style manifolds that go through the inner fenders, they keep the engine bay cooler, and open up the exhaust breathing.

I have an external clutch slave cylinder and no mods to tunnel . If you get the British V8 newsletter Dale Spooner has a write up on what he did. He looked at my set up and refined it to what he used, which ia an improvement.
It is not expensive and like you, I prefer it to the HTOB
I must admit I was lucky to get my T5 at that price and internally it was great --but I did the syncros and bearings as it was a reasonable cost.
Gil Price

> Plans are to use an 8" Ford rear end around 3.08:1.

8" or 8.8" ? They are completely different styles of Ford differentials.
3.08:1 is a common ratio for an 8.8" Ford rear. 3.00:1 was available for
the 8".

> I'm going to rebuild the 215 first. Any advice on what pistons or other
> components to use is appreciated. Healthy performance coupled with
> daily-driving tractibility/reliability is the goal. 180 hp/200# torque
> is certainly enough for this ol' guy.

What Olds cylinder heads do you have? Oldsmobile used a flat top piston
and altered compression ratio using different combustion chamber volumes:

valve valve vol bolts notes
diam diam cc's per cyl

Olds 215 1.522 1.353 38 6 casting suffix -534
Olds 215 1.522 1.353 43 6 casting suffix -829
Olds 215 1.522 1.353 51 6 casting suffix -746
Buick 215 1.500 1.313 37 5 all Buick 215
Buick 300 1.625 1.312 54 4 1964 Buick 300

The typically available pistons are SilvoLite cast units that give
approximately 8.8:1 (p/n 1718) or 9.6:1 compression (p/n 9598), using
the 37-38 cc heads. There are also higher compression pistons available
for the Buick/Rover heads. I've got Buick and Rover engines, not the
Olds versions, but Dan Lagrou of D&D ( ) shows
a different part number piston for Oldsmobile pistons, with a note that
says they have the proper valve relief notches for Olds heads.

If you don't mind running premium pump gas, getting the compression up
is a good thing to do to these engines. If you have larger chamber heads,
you may want to swap them out for the -534 casting high compression heads.
D&D sells heads for $75 each. If you decide on a lower compression ratio,
then pick your cam accordingly (moderate overlap and duration).

With a performance cam (Crane, Isky, Erson, and Crower all make them for
the 215), you'll want better than stock springs. There's a SBC part number
that works for Buick and Rover heads but it looks like D&D has a Sealed
Power VS-526 part number for an equivalent Olds spring.

Ted Schumacher ( ) caters to Rovers
and carries a nice true-roller double roller timing set for $60. If there's
room in the budget, a lighter flywheel will make the engine feel more
powerful, particularly in lower gears. Ted, D&D, and Woody Cooper all carry
them in aluminum or steel, drilled to accept a variety of pressure plates
and clutch discs (depends upon the input shaft of the tranny you choose).

I fool around with Triumph TR8's which have a bit more hood room than
MGBV8's so I'm not sure if an Edelbrock Performer Rover intake will fit
or not. If you already have the GM 4 barrel intake, it's not a bad piece.
The Offenhauser Dual Port is very low, so should fit. The Dual Port is
not the same as a dual plane. The dual port design has the runners split
into top and bottom sections with the plenum split fore and aft (rather than
the usual side-to-side). It's essentially two single plane intakes stacked
on top of each other with the 4 barrel carb primaries feeding the longer
path lower runners and the secondaries feeding the shorter path upper
runners. It's an interesting concept but the packaging required to fit
within a carb intake envelope does compromise the design. The Offy Dual
Port has the reputation of being a good low to mid range intake with
excellent throttle response and fuel economy (probably the best cruise fuel
economy based upon BSFC tests performed by David Vizard, at least on a
small block Chevy). It's not a high rpm intake but Offenhauser says you
can trim the dividers back at the head flange to pick up some top end
power and RPM. I'm currently running a Dual Port on a TR8 and am surprised
at how well it works (very smooth across the rev range) but Ted at TSI has
dyno'd both on a TR8 engine and says the Performer pulls quite a bit better
above 4000 RPM.

Ted at T.S. Imports provided the results of a dyno test on a Rover 3.5L
and the results were published in a 1995 British Car article "Improving
the TR8 & Buying a TR8", Dave Destler, 1995 British Car, pp 35, 47-48.
The "V8 on the Dyno" sidebar gives the relevent information:

conducted by Ted Schumaker of TS Imported
rebuilt 3.5L Rover V8
stock bore and stroke
unmodified cylinder heads
22 lbs steel flywheel (stock is 32)
Tri-Y TR8 headers
10.5:1 compresson cast aluminum pistons
Isky 264 hydraulic flat tappet camshaft
Rover windage tray

Run 1:
Holley 390 carb, vacuum secondaries, #51 primaries, #58 secondaries, Offy
JWR dual port manifold, 22 degrees advance, vacuum advance disconnected

RPM Torque HP
4000 211 161
4500 210 180
5000 205 195
5500 189 198
5700 189 205
5900 181 204

Run 2:
Holley double pumper 390 carb, mechanical secondaries, #62 secondary jets,
Offy/JWR dual port manifold, 28 degrees advance, vacuum advance disconnected

RPM Torque HP
4000 --- ---
4500 219 187
5000 210 200
5500 197 206
5700 191 207
5900 182 204

A later test was run with an Edelbrock Performer Rover intake and and the
results published in the MGB V-8 Newsletter, Issue III, Vol. I:

Run 3:
Edelbrock Performer Rover dual plane manifold, 30 degrees advance

RPM Torque HP
4000 232 177
4500 230 197
5000 222 212
5500 215 226
5700 217 235
5900 207 232

Note that the Isky 264 cam is a grind most Isky retailers don't even know
exists. Ted is the only guy I know that carries it and says it pulls well
from 3000 to 6500 RPM. The above numbers are for an engine on an engine
dyno. Usually, they are run with open headers (no exhaust system), no air
cleaner, and no power draining accessories like power steering pumps, air
pumps, etc. The trick is to get as much of the dyno power to the rear
wheels as possible. A properly sized dual exhaust with cross over, cold
air ducted to a large air cleaner, no catalytic convertors, air pump,
etc. all help.

Dan Jones
Dan Jones

Don't forget that if you use the B gearbox and the adapter plate that you must saw off the original 215 starter mount from the block. You'll be stuck with your choice forever unless you build another motor. I considered this myself an actually bought the kit and had a flywheel modified. Roger Parker advised me against going that route. His words were something like.. "V8+MGB gearbox =BANG!" I sold my conversion bits and bought a Rover box.

It's time for another round of thanks. Dan, your article (!) is extremely informative. It must have taken you awhile to put all that together, and I appreciate it. I'll check the casting numbers on the Olds heads the next time I get out to the shop and post back to this thread. I do have the GM 4-barrel intake manifold.

Justin, I do definitely plan on the RV8 manifolds. I was aware that Dan Lagrou has the T5 for MGB for around $1000, which is why I didn't buy the used one for $900.

Gil, thanks again. If I can do the external slave cylinder without modifying the tunnel, that adds a new option. And no, I don't get the British V8 Newsletter. How do I subscribe?

All - I had almost given up on the V8 idea, but then I got to thinking why did I buy this 74.5 GT in the first place? And the Olds 215 is sitting in the shop. The GT is currently my daily driver with the 1800 and no O/D. The least I would do is put in an O/D transmission - which I have. But again, I bought this GT with the idea that this is the perfect V8 candidate. You've all been extremely helpful in pointing out the consequences of various decisions. Thanks!

Allen Bachelder

You might keep your eye out for a Toyota supra adaptor set up second hand, could be quite cheap.
We all use them here as there are no tunnel mod's except for a very very light bit of tunnel dressing on one side. The supra box is good to 500BHP and comes in both four varieties of gear ratios and gear location lengths(we want the longest one "d"). A guaranteed rebuilt one (your choice of ratios) is about $750 Australian ($400 US). The adaptor/bell housing and bits is about $500 aust' new. Allot less, of you look around. Don't use the supra slave though, its three quater inch and too small.
Jeff Dellow in Sydney (Australia) makes them and sends them all over the world. The supra box looks the same as the corrolla and some people use these instead cause they're cheaper. The advantage of the supra box over is that its stronger and lighter by about 20 kg.
So if you really want to leave the tunnel alone, (like me) this is the one for you.

I've driven a Supra before (the last generation of them) and that car was SWEET. The gearbox shifts smooth as silk. The ratios felt great... what an incredible car! They even have them in 6 speed varieties too! I wonder what shipping would be like from aus to here. Probably not cheap! probably worth it though! (1250 Aus = $921.00 US)


More thanks! Peter and Justin, I have a Nissan 280Z box in my 1800 Magnette and have thought it would be a nice box for the V8 too, but the Rivergate folks who build the kit to fit the Nissan box to the 1800 haven't tried the 215 yet. Can I get the Supra box from a scrapyard here and order the kit from Jeff Dellow?

Allen Bachelder

You can, but they're EXPENSIVE. I did a quick and dirty search, and they're over $1,000. Dellow's for $750 AUS is a steal.


' Appreciate it, Justin. Expensive, but if a T5 from Lagrou is going to cost me $1000, then $1400 (including for a slick box that fits in the tunnel doesn't sound terribly out of line. Except the rebuilt MGB O/D box is at hand and it looks like the TR7/SD1 box is mine for the taking. Of course I can always sell the MGB O/D box for a substantial sum...

Dan: I'm going to ask perhaps a dumb question. Where do I find the suffix? One of the heads is stamped
"S162975G" on a boss on the end of the head. The other has no number here at all. Between the 2nd and 3rd cylinders on each head is stamped "106". Where else should I look?

Allen Bachelder

Geez...this thread grew by leeps and bounds!

1 - the 8" Ford had a multitude of gear ratios. I began with a 2.79 from a 1979 Ford Granada...and currently have an Auburn 3.27 posi installed.

2 - I have an Edelbrock 500 cfm - the block is a tweeked Rover 3.9 courtesy of D&D

3 - The T5 is a great final drive is a 0.63.

4 - Join the British V8 group and subscibe to the newsletter!

5 - If you can manage, make it to Grand Rapids, Michigan the weekend of August 12-15 - the V8s will be in force (contact Steve Carrick at for more information).

6 - Save the second weekend of June 2005 for the V8 meet in Terre Haute, Indiana!


1974.5 MGB/GT V8 conversion
rick ingram

Justin, I looked at the six speed but they wanted over two grand!
Yes, jeff will sell you his bell housing or any part theroff. This is probably the best option for you as the bell housings not too heavy or expensive and shouldn't cost too much to ship. Then look around locally for a box. I'm sure there are plenty as they can be got pretty easly here despite the supra never having been sold locally. Every one looking for a gear box upgrade liked the strength, compactness angle and Jeff has been earning a living making adaptors for them. He will fax you a whole lot of info' if you ask.
The best supra box for MG's is the W58 with a 0.78 top ratio, W55 is next best.
There is a vaste amount of information in the archives on toyota boxes, ratios and the models that they were in, just search supra, or toyota etc.
Jeff will fax you information, lists of parts and prices if you ask him, I don't believe he's on the internet. Just pick the bits you want or can't get localy. I would suggest you get your clutch locally as this is a heavy item to ship and could be better.
I eventually used a LUC spring plate.
Ask if he'll do the larger slave set up for you as this is a one and onesixteeth inch and perfect for MGB V8's. I accidentally got the three quater inch supra slave and had to substitute a one inch range rover one.
You're going to love this conversion when done, you more than double the torque and horsepower and the car ends up lighter by about 30kg. The weight distribution moves back a little and actually improves handleing.

For the Briish v8 Newsletter go to If you can still get it, the back issues are wonderful for someone new to this addiction. This has been an invaluable source of information for me as I do my conversion.
Phil O

Seek, and ye shall find... :-)


dellow automotive PL

W58 box
1st 3.28
2nd 1.89
3rd 1.27
4th 1.00
5th 0.78


stick posn
D-21" the MG one

This is his price list in Australian dollars AS of 2 yrs ago and inclueds our Tax (which you don't pay)

Bellhousing pilot bush &pivot ball $395Australian
steel clutch fork and clip $65
thrust race an carrier $55
adjustable push rod $20
speedo cable $55

This would be the minimum but you might want to get a
tailshaft yolk $95

the gear box is $695
As I said, ask for the 1 1/16 slave set up which gives just the right amount of travel for the least effort when retaining the MG master cylinder.
You can also buy a pressure plate $100 and Clutch plate $95 but the former is heavy and might not be worth the cost of shipping. There are also better pressure plates around.
Don't get the supra slave, at 3/4 inch it makes the clutch way too heavy and over driven. If they don't do the larger slave set up any more, you can make your own adaper bracket easily enough, as I did and bolt on what you like most.

Hey, another round of thanks. I really hit paydirt on this thread!

Rick, I wouldn't miss the Twist reunion if I had to walk there (650 miles). We won't be in a V8 car yet - no doubt in our '73 1800 or "Nettie" our '58 1800 5-main, 5-speed Magnette. ' Sounds like you did the same conversion I'll be doing: a 74.5 B/GT. I'll be anxious to see your car!

Peter and Justin, I really appreciate the info on Dellow Automotive. Many thanks, Peter, for the price list. Can you tell me, specifically, which years of Supra transmissions I should look for? Did they use this transmission in any other application? Like pick-up trucks?

Greg, Thanks for your heads-up. The bid price on that T5 is still pretty reasonable. One more option...

Already, this is fun!
Allen Bachelder

' Looks like this thread has pretty well played itself out. It's been a good ride and I've learned a lot. Thanks to all!

"When the horse is dead, dismount." =) You need a supra trans from a 93-97 Supra. That's the last generation of them, and the ones that have the good drive lines in them. My brothers Celica went for 226,000 miles w/o ever having broken down. Toyota makes great products, and I wouldn't hesitate to put in a supra 5 speed box for 1 second.

Keep asking questions! Questions are good!

Archives for more details on toyota boxes/models, they're there.

Ok I've done my homework, and the coveted W58 supra 5 speed box was used in these applications: 82-98 Supra (5M-GE, 7M-GE, 2JZ-GE), 86 Supra/Soarer/Cressida (1G-GTE), 82-85 Celica (US 22R-*). That really opens up the search options a LOT. W58 rebuild kits can be had for $300.00 stateside, and the info Greg put up about the bellhousings all but finishes off the project. The rest should be straight forward. If one were so inclined, they could easily piece meal this thing together and do a weekend swap.


Hmm, sounds like it might actually be worth shipping Jeffs boxes, cause his come already rebuilt and the exchange rate would put them at a little over $400 US.
Mind you he is slow at rebuilding these boxes. Took a month for mine to arrive.

1982-1986 Supra and Cressida transmissions are available locally for as little as $132. $300 for a rebuild kit plus about $530 US for the Dellow kit comes in around $975 plus shipping from OZ and I'd have the whole thing for around a grand depending on shipping. Not real cheap but competitive, to say the least.

Would you guys say it's BETTER set-up? I still have to get a flywheel for the Olds 215 (which one?) and a clutch (again, which one?). I'm presuming this will fit the MGB tunnel without modifying the tunnel, right?

Peter, I'm not sure I understand your data about stick position. What are positions a, b, and c?

Again, thanks guys. BTW, I sent a check off for my subscription to the V8 Newsletter today.

Allen Bachelder

The transmission weighs something like 77 lbs. I figured a 100 lb package. If you shipped it from Dellow's shop in Aus to me here in Michigan, the cheapest rate was $635.00 AUS YEAH RIGHT! I have an e-mail into Jeff right now finding out about the kit sans the box. Something else: the W58 box was built for a 230 hp inline 6 cylinder, I would think that a rebuild would have to beef that up some to make sure it holds tight. I've heard of those boxes being built to take up to 550hp, so it can be done.

I'll report back.

I thought this horse was beaten to death? Looks like it's still a-floppin' to me!

All the info you'd want on this:




I just bought a w58 Celica transmission from a local salvage yard for $75. Look on, they're plentiful at cheap prices. It looks like a stout piece and I've read numerous claims that it can handle 300+ hp with ease. I plan to make my own adapter plate to adapt it to my 5.0 Ford. Yeah, the smarter thing would be to just buy a t5, but I like trying stuff like this just to see if I can do it. The w58 transmission will actually bolt right up to an ax15 Jeep bellhousing (both manufactured by Aisin Warner). A company called advance adapters ( makes an adapter plate to mate the ax15 bellhousing to the 302/5.0 Ford. It's about $250 so I might end up buying one if I can't figure it out myself.

Ryan Reis
Ryan Reis

Just love that 3000bhp street legal car at rod shop.
I wonder if he's ever actually attempted to take it for a drive? Is there room for a passenger in there or is it all full of engine?

The box comes with four different gear lever locations. MGB's need the longest one. This is infact is a little short. I went to alot of trouble to get the lever in the orrigional MGB position w.r.t. fore and aft, which ment some light dressing back under the heater and bulkhead. If I were doing this again I would opt for having the lever 0.5 to 1 cm forward of orrigional. This would mean leaving the bulkhead/heat alone altogeather without generating any problems wrt radiator clearance.
You need to locate the back of the box as high as you can go. This has the benifits of allowing free movement of the gear lever in the orrigional tranny tunnel hole and gives clearance between the drive shaft and the heel board brace at the back of the car. This last is important because since the box is shorter than the old MG one then the shaft is at a shallower angle.
w.r.t the tanny tunnel hole, you may or may not realize (I didn't) that it is offset about half an inch to the port side of the car. This is because the MG gear lever was offset. Your toyota gear lever (like most gear boxes)has no such offset and unless you wish to relocate the tranny tunnel hole then the lever must be high.
Another advantage of having the rear of the box high (and the motor as low as poss') is that this tilts the heads forward and away for the engine compartment bulkhead, giveing you more clearance.

This thread was discussed between 15/04/2004 and 23/04/2004

MG MGB GT V8 Factory Originals Technical index

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