How strong is MGB rear end.

If I install a 305 Chev completely stock eng and automatic tranny in a 78 MGB, will the rear end take the extra torque?? Frank

If you don't do jackrabbit starts.

should, but the front suspension will not like you much. the stock rear end can do up to about 280hp, but that's pushing it, past that things start to break, but the real enemy is the torque, it'll take about 250 to 300 ft/lbs but I personally wouldn't run anymore than about 250ft/lbs through it. The extra weight up front will be brutal enough though! ::o

Personally I don't understand why you wouldn't want more power with the 305. Kinda defeats the purpose of the v8 if you don't build more power with it in my eyes...
Just my thoughts

The automatic will help with the longevity, clutches break parts. You will want to change the ratio though because the engine will really be buzzing at freeway speeds. So if you have to change the ratio anyway, why not change to a stronger rear end while you are at it? Do a search and you will find tons of threads here on the subject.

thanks for your reply Jim.I want my "B" to look unaltered as much as possible.I love the way a MGB looks when It's stock and really clean.I only want to be able to run with the traffic on the interstates,plus a little more go at the redlights.
Would another engine be better suited for my needs? Keeping in mind that my finances are very limited.

If you can find an inexpensive 60° V6 you can use it. They were plentiful in the early 90's Camaros and Firebirds, should be a few in the junkyard probably. The downside to using a 305, it there are not swap components for it, everything will have to be custom. Headers and mounts for sure. What trans are you running, TH350 or TH400? I would suggest a 700R4 or 200R4 just so you have overdrive otherwise at 65 your engine RPM will be like close to 3000 or so, and this is not easy on the fuel and in turn your wallet, sometimes you have to spend a bit of money up front to save in the long run.

Dan

I ran the stock MGB rear diff in my car with the SBC (350) for a couple of years, no problems. I am not the kind of guy to smoke the tires all the time, however. Then I realized I really needed a limited slip to put that power to the ground, so I am runninng a Ford 7.5 with limited slip.
On the engine choice, the SBC is easy to obtain, get parts, modify, etc. If you want to fit it under the stock hood, you will have to alter the fire wall and probably the tranny tunnel (look at my avatar and see the air filter sticking up from the hood). I did an auto tranny at first, but decided an MGB just isn't right (no mater what engine) without a manual tranny.
As most of us agree on the dark side, it's your car, do what you want with it and have fun.

Brad

Frank, is there a particular reason why you want the SBC engine? I men, it's HEAVY, difficult to fit, and there are no standard swap parts like mounts and headers. If a 305 seems about the right size to you, why not go with the 300 Buick? It fits, all the swap parts are available, and costs at least $600 less than doing the BOPR swap. Best of all, it is only 50 lbs heavier than the original engine and there is ample headroom for future power upgrades if desired.

JB

Yes, it is an excellent choice, provided you are willing to put in the time to find the right engine, which would be preferably, a 300 Buick 4bbl with aluminum heads and intake, most likely out of a '64 Buick Special. It will have higher compression and will weigh nearly 100 lbs less than the later iron headed 300 with iron intake.

It uses the GM corporate BOP bellhousing which is common as dirt and costs about $50, (different pattern than BOPR) ditto on the flywheel (both same as 350 Buick). The T-5 transmission will bolt right up. So will the 2004r 4 speed auto with lock-up (effectively 5 speeds). Gear ratios are far better than the 700r4 which will not bolt up without an adapter plate.

These engines can still be found in running and usable condition for the extremely low budget conversion. Check on the various Buick forums.

It is essentially an iron block BOPR with a taller deck so the BOPR headers, mounts, etc all work fine.

Optional power upgrades include displacement increases up to 350 cid (using 350 crank) and aftermarket heads and intakes so an iron headed engine can be used, but the aftermarket heads are not cheap.

Jim

So if one got cast heads with the plan to just get his B running with a V8. Al heads and intake could be done down the road

You may have some trouble finding a pair of heads that aren't "punky" in the area of the water jackets. These things are old and have sat around a LONG time in various yards, just corroding away. Expect to have larger seats and valves installed anyway, have this area checked at the same time, obviously. All of the valve train upgrades for the TR8/Rover will work on these heads.

The four barrel aluminum intake will be much harder to find, they just don't turn up. People who know about them have picked the place clean.

Expect to pay more for the aluminum upgrades than you paid for the engine.

A whole lot of TR8 folks have scooped up the good heads and cranks for their 3.5 Rover engines to build a common stroker version.

I have a really sweet Buick 300 engine. An original aluminum head/intake four barrel version, pretty much maxed out in every area which I'm taking to my grave with me. I just can't recommend these engine enough. Absolute torque monsters, diamonds in the rough that respond wonderfully to every single simple high performance trick ever invented. A big plus is that they share multiple parts with the GM215, Rover, BOP V6, and Buick 350. An example would be that the entire aluminum front end assembly is nearly identical to the Buick V6. Timing cover, water pump, timing chain, oil pump, fuel pump, etc. This means that all of the up-grades from the Buick Turbo Regal engines will bolt onto the front, all of the Kenne Bell speed equipment is a bolt on, headers are the same as the ones offered for the 215 conversions, over-sized oil pump gears/housings/pump covers, Turbo oil pick-up tubes and screens, and on, and on; the list never ends ! !

Just a WONDERFUL little secret. If you can find one, buy it NOW ! ! !

Luck,

TC

You have to know where to look of course. The Buick guys don't consider the '64 much of a performer and tend to swap it out for an iron head 300, a 340 or a 350 so they are more likely to have the parts you need. Last set of heads I bought I gave $100 bare off ebay. Wilwood/Wilpower sells a single plane to fit the 300. Aftermarket parts are around, just not that cheap. Best bet is to find a complete '64 even if it means pulling it from a running car. But, an iron head motor could be used and is still lighter than the SBC. Later on if you ran across a '64 runner and wanted to swap you could put your iron head motor in the Buick. The heads and intake do show up on ebay from time to time, other possible sources might be Hemmings, HAMB, V8Buick, etc. The motors are still out there, you just have to look.

Jim

Wow ! I didn't know that anyone was offering a four barrel aftermarket intake for the old 300. Have you got a link to where they're being sold? We have another aluminum head 300 (stock 2bbl manifold) and could sorely use a four barrel intake for it.

Thanks !

TC

Check out the intakes on this page:

http://www.mez.co.uk/ms12.html

The single planes are near the bottom. I don't have the contact info handy for Greg Williams but as I recall he makes an intake that fits the P76, it just has a little thicker flange I think, and he said one for the 300 wasn't much different. Don't know for sure if he has made one yet or not but it sounds like he'd have no problem with it. Also these guys or possibly TRS (Triumph Rover Spares) have spacers to adapt Rover intakes to the taller deck engines. Hope that helps.

Jim

So if I were to find a 340 for $400 Would that be awesome?

Yes and no. The problem with the 340 is that it has a taller deck than the 300 which causes quite a few problems. It is impossible to get it under the hood using a stock intake. Nobody, and I mean NOBODY makes an aftermarket intake for it and spacers for a Rover intake raise the intake over an inch more, if they were available. Then it is also wider. For an idea of what is involved in fitting this engine check out the 20 pages so far on this link, especially the steering mods:

http://forum.britishv8.org/read.php?2,274

In short, it is a Master's challenge. I'm not in any way saying it can't be done, but the 300 fits easily and can be stroked to 340 with the 340 crank. Much better to stick with the 300.

Jim

Those manifolds are SWEET, nothing for the 300, but I still want every one of them for my 3.9 Rover. I'll send an email to see where they are with the development for the 300.

Although, I love your idea about using the 215/Rover based manifold along with spacers, makes great sense and an easy solution. And you totally right about the 340, just not the right engine for transplant, the 300 or Rover is SO much more "made" for the MG.

Thanks! Terrific link !

TC

I've forgotten the deck height of the P76, I think it is within about 1/8" of the 300. Also note that some of the IR manifolds will bolt right up to the 300 as the only attachment between the sides is the throttle linkage.

These engines have a lot of space between the ring package and the piston pin. Enough in fact to accommodate the longer stroke of the 340 or 350 crank and still use the stock 300 rods and retain a 1.55 rod/stroke ratio. The crank mains have to be cut down and switch to slipper skirt type pistons. I think there have been a couple of pistons found for this build but do not remember what the CR was.

Jim

"A doggy 305 and slush box would ruin the ride,sit high in the bay,be nose heavy(as noted) require more work..."

I resemble that remark!

Brad