MG Sports Cars

I am looking for pointers on the major hurdles with this conversion. I have a 1964 MGB with the original motor that is very tired now, and leaks oil very excessively, but still runs. I've read about the 3.4L conversions and the "kits" out there. I have a GMC small SUV donor car with a 4.3L V6. I want to use the GM fuel injection system and electrical harness. The goal is a reliable car with the power and future upgrades of a big V6, but I prefer to keep the MGB exterior and interior as close to OE is possible: chrome bumpers, no hood scoop (if possible), 60s era gauges. I want to put in a manual transmission. I've worked on cars my whole life and have restored a few and replaced engines, etc., but have never attempted a conversion like this before. I believe I will have to rebuild the transmission tunnel for this. Correct? Here are my other questions:
> At what point in the car do I hook up the GM wiring harness? With a newer, modern fuse box?
> Will I need to use a new set of gauges or is there a way to use the stock guages?
> What motor mounts are needed for this? Does someone have make and model #s? Or are they custom?
> Which manual transmission is best for this?
> How do you connect the GM transmission to the drive shaft of an MGB rear-end?
> Should I invest in a non-MGB posi-traction rear-end instead? If so which one?
> Are there challenges with putting a fuel injection in to an MGB? and are there emission control sensor challenges?
> I've seen pictures of the headers routing through the fender wells... are there other space issues?
> Will the car handle still handle well afterwards? Or will it be more of a "lead sled"?
> Is the stock MGB car frame acceptable for the extra power and torque?

I really appreciate to opportunity to learn from all the expertise on this forum. Thank you in advance for your input.

The 4.3 has been done, and has about the same level of difficulty as a SBC swap. That's not to say it's a particularly good choice though, the one 4.3 car I was familiar with was later converted to the BOPR, after which the owner was much more satisfied with the car:

[www.britishv8.org]
[www.britishv8.org]

But here are what we have in the gallery:

[www.britishv8.org]
[www.britishv8.org]

As you can see an attractive car can be built with that engine, but Mike was always complaining about the vibration. Personally I think a 300 Buick makes a much more practical swap, with all the needed parts available and reasonable costs.

Jim

Hi Chad,

I'll give you my opinion on some of your questions.

Quote:

I believe I will have to rebuild the transmission tunnel for this. Correct?

You've got a more narrow tunnel in your 64 than the later cars do but I see a lot of guys are able to get a T5 into the early cars. I think "rebuild" might be too strong a term...."modify" might be better.

Quote:

> At what point in the car do I hook up the GM wiring harness? With a newer, modern fuse box?

I think there are a couple of different approaches you could use. I've created a stand alone harness for my FI wiring with it's own separate fuse box. It needs a source for constant power from the battery and one from "key on". My original harness/fuse box are still in place. There are a couple of additional interfaces to the MG harness like the tach wire but it is minimal. You need to do a lot of planning before you start with this task.

Quote:

> Will I need to use a new set of gauges or is there a way to use the stock guages?

I'm still using my stock gauges. I have a later car, a 68, so my coolant temp gauge is electrical which is straight forward, just need to find a place to mount the sender. Not sure about yours. My oil pressure gauge is the later mechanical gauge so no issues using it. The only other challenge will be the tach but there are several different approaches you could use there. Is yours an electronic or mechanical tach? I bought a replacement circuit board for my tach so it allows me to adjust for any number of cylinders. Do some research on this, there is a lot of information out there on all of this.

Quote:

> What motor mounts are needed for this? Does someone have make and model #s? Or are they custom?

I'm quite sure you're looking at custom motor mounts.

Quote:

> Which manual transmission is best for this?

A lot of guys use a T5 since they are very common and relatively cheap. There are other choices out there, do some additional research on this if a T5 won't work for you.

Quote:

> How do you connect the GM transmission to the drive shaft of an MGB rear-end?

You'll want to go with a new custom drive shaft for this.

Quote:

> Should I invest in a non-MGB posi-traction rear-end instead? If so which one?

A lot of guys replace the original rear end, a lot keep the original. You have a weaker rear end in your early car so you may want to think your way through this decision.

Quote:

> Are there challenges with putting a fuel injection in to an MGB? and are there emission control sensor challenges?

Wiring is the biggest challenge, I think, if you're using a common computer. What year is your donor vehicle?

Quote:

> I've seen pictures of the headers routing through the fender wells... are there other space issues?

I believe your going to have to do some modifications to your firewall especially since you have an early car.

Quote:

> Will the car handle still handle well afterwards? Or will it be more of a "lead sled"?

Yes, the car will handle similarly to the way it does now.

Quote:

> Is the stock MGB car frame acceptable for the extra power and torque?

Yes, as long as you take care with the modifications you make to get the engine/transmission into the car.

I would suggest that you decide what your goals are for the car and then spend some time planning how to meet those goals.

Scott and Jim, thank you so much for your responses. I can't say enough about that valuable information.

I've done some additional reading. Do I need to plan on moving the steering rack with one of these Conversions?

Please consider the following and let me know your advice. I live in the Reno Nevada area. My goal with this car is to have is very reliable and fun to drive, and with some impressive power. However I am not one of the 300BHP gents I've been reading about. I will ensure the car handles well, stops well, and is ultra-reliable. I am not concerned about if it sounds like a V8, and if there was a vibration with the V6, I would make improvements until it stops. I want to occasionally race it on the track. I want to zip around mountainous corners with the top down around Lake Tahoe; take the wife on a date. I want to drive be able to drive it at 75-80 mph (75mph speed limit there I believe) for seven straight hours, minus gas stops, between Reno and Las Vegas.

I will be doing this conversion myself on nights and weekends, and a handful of vacation days, with help from friends/my brother. I already have the donor vehicle with all the 4.3L fuel injection, wiring, accessories, etc. The motor might need a rebuild but that would be less than $1K --- will know soon. My goal would be to finish this project in the next 12 months, and keep the additional costs (remaining budget) below $3,000.

It sounds like the BOPR is an easier conversion. However, I don't have a Range Rover or other donor vehicle. Yes I would get more power but the 4.3L will be plenty for me, but what are the conversion advantages over the 4.3L? It looks like the exhaust is still going through the fender wells. Are there other aspects I should consider re how a BOPR conversion would be easier than a 4.3L conversion? I could sell the donor vehicle etc and pursue the BOPR, but with my goals, and remaining budget, what is your advice please?

The Buick 300 you mentioned Jim. Is that 300 cubic inches? What are the most popular cars that came in?

Chad, Rear distributor and headers are your only real tight spots. Study the links Jim B. showed, maybe PM some of those guys for tips.

Chad, I would advise not going with the 4.3. I had the 4.3 (and before that the 3.8) in my Mgb gt. Among numerous other items, the 4.3 will require major revision to the front cross member and unless you take the headers through the fender wells there is only about 1/8th inch space between the "hugger" headers and the frame rails. Additionally you will have to make your headers if you go this route. With so many other more viable options it just does not make sense to do this. The list goes on, but this is the reason I have been running the Rover V8 for the last seven years.

There are a lot of threads on this forum about different engine choices and common elements to most. One of the most common themes is that the "free" engine is not free. The reason being that the cost in time and labor to fit a less common engine will easily offset the cost to buy a more common engine. Now you say you'd like to have it done in 12 months and this swap has just gone from difficult to nearly impossible for most people. Seriously, with that timeline you should think very hard about selling the engine you have and buying something that is a quicker and easier swap. And just so you know what the difference can be in real world terms, Glen Towery used to do the BOPR swap in a weekend in the customer's driveway. It will take you longer, but that leaves you time for the rear end, etc.

So unless you are for some reason married to the GM 4.3 let's look at practical alternatives that can meet your goals and timeline. First the BOPR naturally, as Buick, Olds and Rover V8's have long been the mainstay of the MGB conversion hobby. The swap is very mature, and parts sources are plentiful. Displacements from 3.5L up to 5L are possible. It can be more expensive than the other swaps, primarily due to bellhousing, flywheel and HTOB costs. The 300 Buick is a variant of this group with a more durable cast iron block and much cheaper bell and flywheel. Stock '64 4bbl engine made 250HP and 335ft/lbs of torque. The horsepower doesn't sound like all that much but the torque will make your day. These engines can be found in running condition for under $300. The ideal donor is a running '64 Buick Special but it is likely to have an automatic. The deck is 9/16" taller than the BOPR so hood clearance can be an issue. EFI is a possibility using the Rover system with intake spacers or a 4bbl throttle body and injector bosses added to the intake. Plenty of overhead for performance improvements.

The 302 Ford swap is also popular but requires a modified crossmember. However, a kit is available from Mantell Motorsports.

The 3.4L GM V6-60 has proven to be a very good choice as well, giving a very good balance of cost/difficulty/power/economy. It is generally considered to be a better swap for those reasons than the larger 4.3

Just about anything else is going to require that you design and build the headers and motor mounts at the very least and do not forget the 90/90 rule that 90% of the build takes 90% of the time but the last 10% also takes 90% of the time. It's fairly accurate.

Jim

I agree with Jim that there are better engine choices out there. The 60 degree Gm V6 engine has been swapped into lots of MGB's and you have 3 different vendors that you can buy conversion parts from:
[bmcautos.com]
[www.classicconversionseng.com]
[www.britishcarconversions.com]

You can go with the older iron head Camaro 3.4 engine and transmission with either the fuel injection or with a four barrel carb.
You can go with the newer FWD engines that can be converted to RWD using bell housings, transmissions, and front cover/water pump from the Camaro 3.4 drivetrain.
The GM 3500 in converted form has approx 235 hp with about 220 foot pounds of torque.
I converted a GM 3400 and put it in my TR6 and I am quite happy with the results.

Cheers
Byron

Quote:

I want to drive be able to drive it at 75-80 mph (75mph speed limit there I believe) for seven straight hours, minus gas stops, between Reno and Las Vegas.

Is this realistic, given that you need to cover 450miles with a 12 gal (US) fuel tank.
I run a 302 Ford and the best mileage I've had at those speeds is 23-24mpg. If you want to achieve the required 37-38mpg and/or driving range, I'd recommend the 3.4FI engine suitably geared with the possibility of going to a larger capacity fuel tank - there is a 16 gal FI tank available commercially for the MGB.

Chad,

I have an MGA with a 4.3L engine. The motor itself is fine. The 4.3L has potential for horsepower. That being said it is a wide engine, as wide as a Chevy 350. The motor will be a tight fit even for an MGB. I had to modify the steering rack (ended up with a Mustang II front end) and had headers custom made. I have a T-5 transmission that works well. At 70mph it is turning approximately 1800 rpms. You will have to modify your drive shaft. The engine sounds good. The weight of the 4.3L should be lighter than the 4 banger currently in your car so handling shouldn't be a problem. I replaced the original rear end with a Chevy from an S-10 pickup.

If I had it to do over I'd go with the Ford 302 due to the width and potential for even more horsepower and the availability of kits for conversion.

Gentlemen, I really appreciate all the valuable input here. Financially I am not far at all in to this project--- only $400 for the donor vehicle and 4.3L. With your advice, I will see if I can find a Buick 300 or Ford 302, and a donor car. I like having a donor car because that way if the motors runs well in the donor car, I won't have a problem replicating that in the MGB, and I like having all the accessories available. Graham, I was only speaking conceptually about the trip to Las Vegas. LOL. I don't need exceptional gas mileage; I can stop for gas. By comparison, with the OE engine in the 64' MGB, it had no cruise control and no overdrive, so at that speed, you'd have to be at like 4000+ rpm, and it was not a peaceful drive. I started looking at craigslist and ebay for a Buick and a 300--- there was not very many choices out there nationwide. Should I be looking at different websites? Or should I post my need somewhere?

Sorry for my ignorance with this: If I find a good motor, but not a donor car, is starting it up on an engine stand an option? Or maybe a temporary frame made from 2x4s? (with an oil PSI gauge hooked up, wiring harness, radiator, external fuel, etc.)

I would be willing to pay a finders fee to find what I need, if you have a recommendation on who I should talk to. Any of you, if you're in the Reno/Carson City area, please let me buy you lunch in appreciation for the huge hours and dollars you've saved me with your advice.
Chad
cwestom7@gmail.com

Chad, I'd check with the guys on the V8Buick.com forum, Hemmings, and maybe a few of the other forums like the HAMB plus AutoTrader and Craigslist (Tempest). They are out there, you just have to do some searching. I know Sean (V8Buick and occasionally the MGE forum) has about 50 SBB engines out in his barn.

Jim

Chad,

I've run donor engines in and out of cars before... Some intelligently layed out 2x4's and straps can secure an engine adequately. Just keep in mind that issues may not show up in a quick 5 minute start up of an engine. Oil pressure (and related knocks / ticks), for instance, can look normal with cold or warm oil, but it can then take a major dive when things heat up.

-Mike



Edited 1 time(s). Last edit at 01/22/2015 12:05PM by Addicted.

I'd recommend a leak-down test first to assess the overall condition of the rings and valves. Perhaps a compression test to differentiate between the two. It can be run on a stand. I'd make sure it's sturdy and stable, A 4 wheeled stand would be preferred. Bolting the stand down or rigging some braces would be good for peace of mind. Many people have done it. If you run it very long you will need water to keep it cool but a garden hose will work. Mainly you would be checking oil pressure to tell you the condition of the bearings. If that is good and the leakdown is acceptable you should be in pretty good shape. With a tank of compressed air you can run leak down on any engine you are considering in short order.

Jim

Chad, you sound about like me when I started. I'd recommend contacting Pete Mantell @ Mantell Motorsports. He has a kit to do a Ford 302. 302's are cheap and parts are readily available. Easily doable in 12 months. You will want a different rear axle (narrowed) to get the ratios right [same for Buick 300 & other choices too], but Pete can guide you on that too.

Don't get me wrong - and with a ton of respect for Jim - the Buick 300 is harder to source and fewer people can provide help getting it in you MG. Things like building headers - if you've not done it - can set you back months compared to being able to get them pre-made.

2¢ for what it's worth.

Good points certainly. As a clarification, BOPR headers work fine on the 300 too. But if you do have to make headers and engine mounts those will cause big delays. (less on the mounts, and I recommend the head-to-frame rail engine mounts in any case). I had 80 hours of actual build time on the headers for my initial swap. (But they were custom equal length over-the-tire fenderwell headers with 32" primaries) and more time in acquiring materials and then ceramic coating. All these time requirements add up.

The 302 is a fine engine, so is the 300. Both more or less equal on balance considering all factors including availability and historic consistency. I think most people choose between the two based on their manufacturer's preference. So if you like Ford, go with the 302. If you like GM, go with the 300. The 300 swap will cost you less, but finding the engine will require more effort.

Jim



Edited 1 time(s). Last edit at 01/22/2015 09:37AM by BlownMGB-V8.

Jim,

Have you tried leak down and/or compression tests on engines that have been sitting and not started in years?

I'm going to write myself a note to check compression in my car when I take it out of storage, before and after starting it.

-Mike

Hello Chad
let me throw my 2 cents in also, I have a 4.8 ls engine in a chrome bumper and yes it was quite a bit of work. but well worth it, these motors 4.8, 5.3,6.0 are easy to get and not so expensive. the power they make are incredible so there it is my 2 cents good luck brother.

Mike, usually if the engine has been kept dry and indoors (no internal rust) it'll test out OK. Obviously though the more recently it's been run the better.

Jim

I'm late to the party but...

Seventh post from Jim Blackwood: Free is NOT free. The engine is the smallest item!
Reread Jim's post- very good!


Rebuild an engine for only $1,000?
Refresh an engine- maybe. But "refresh" is just a way to say bandaid if the engine needs anything.
Rebuild:
Complete disassembly
Clean up
Bore and hone
crank regrind
new cam or simple regrind
tappets/lifters
conversion gasket set
deck gasket set
timing chain and sprockets
valve and seat grind
springs?
valve seals
valve guides
a couple cans of paint
oil pump
piston set
balance assembly (optional.... for some people)
freeze/frost/core plugs
various seals not included in gasket sets
mill cylinder head and deck surfaces
-a jumbled list of normal plus things forgotten. Under $1K?
Those items that are 'while I'm here, I'm going to upgrade just a little" Riiight.



So the 4.3L V6 serves what purpose exactly? I don't know that this has been addressed.

Your sentence on this: "The goal is a reliable car with the power and future upgrades of a big V6"

The 4.3L is a bit heavier and if I was going to go all the way to 4.3L V6, I would start looking at the 302 V8.

That said, what else is planned on this car? The early MGB axle is not strong nor upgradeable for your needs. You could simply install any 1968-80 MGB rear axle and install different gearing and limited slip if you want to later. If you want, install a wire wheel axle with disc hubs on it and you have a factory narrowed rear axle!

Okay, other than that, are you planning on wide wheels, really decent rubber (say a tyre that holds up for around 15,000 miles- Not 40,000) and many other modifications on the car that will likely exceed your engine conversion costs?

Being forward, our company sells components for the 60Degree V6 conversion namely the 3.4L L32 SFI V6:
My 1980 MGB with the 3.4L has upgraded rear axle, better ratio rear end, limited slip, much better rubber on a wide set of rims that are melting away rather quickly and other modifications. The engine is all stock and was enough to blow out the original rear end partially because I can drive it a bit rambunctiously. 0-60 is probably in the 6 second range but I have never officially timed it. Nothing internally done to the engine as of yet. Programming is basically stock. You want to install a hyperactive 500 cubic inch engine in an MGB with high wear 40,000 mile life 165/75R14 and stock suspension without even replacing the bushings in the rear end up against my car? I would love to. You might have me after 60 by a bit but I'm not sure your going to feel comfortable driving a jalopy at speed. I have driven stock MGBs with bad bushings in the rear that scared me.

Maybe I'm going a bit in the wrong direction but here is my point- a fairly stock MGB with a decent engine upgrade and a few other items can make a fun car to drive. In order to get what you need, you have an early car, your most likely in need of wider rims, something along a 6" plus to get your car to hook up okay, get those in 15" because 14" are pretty much becoming dinosaurs, install a minimum of 185/65R15 to a max of 205 depending on the "Stock" type rear end your using. Replace rear bushings so the car handles and steers straight and to avoid axle wide up (my car also has the late model rear bar which is supposed to helps with this a bit) and consider what you put up front to match the rest of the build.

Another thing to consider- the kits and kit parts are convenience. Your talking about 12 months completion, building everything on your own and for less than $3,000. Are you retired or have a standard 9-5 job to allow you the freedom to take care of this? Are you ambitious? Do you have a workplace that is climate controlled s you don't have those months of no work due to heat, cold or raining frogs? Proper lighting? Proper welding equipment and skill? Proper equipment altogether? Answer no to any of these is going to make this difficult.

Suggestion:
Build a list of parts you will need for an engine such as pistons, rings, gaskets, camshaft, reground crank, etc.

Then build a Separate list of items you will need to ADAPT the engine to the MGB.

Put these lists online and ask people to add to them. For every item you have list such as throttle cable for $18, add 75% more to that item for the nuts-bolt-hardware and little bits to get the item to work!

Figure your list will double and then add the 75% on to the realistic numbers.

When your done, your conversion including welding materials will run to more than $7K will be my best guess. I do not want to discourage you but point this out up front so you can build your roadmap and plan accordingly, not end up bitter with a botched project on eBay.

-BMC.


P.S. Recent share on BMC Facebook:

[www.facebook.com]





and a few of my car in the shop: (I may be submitting these to BritishV8.org for updates on my cars build as the info about my car was back at Stage I, we are at least to stage II by now)