Confused....stock or V6

Ok, heres the deal. My 79 is pretty much stock and non-od and the slowly descending oil pressure makes me think that I will be looking at a rebuild soon. From what I'm hearing a rebuild on the 4 banger is 3-4k and that still leaves me with a four spd.

For the area that I have some fairly high passes to go over to get anywhere and a lot of highway driving after that, so a little more power and another gear would be great....so even keeping the stock engine I am looking at a couple thousand more to get a 5 spd or OD.

In theory the V6 conversion sounds like the best option and I have done an engine swap before (Chevy 350 into a Landcruiser) which was not done under the best conditions, but came out alright. I am thinking of going carbed for the swap if I do it and go 2.8 for now as those seem to be the easiest to come by around here...I think I would like to build a 3.1 or 3.4 as a side project to replace the 2.8 with at some point.

Is my thinking flawed that by the time I rebuild the 4 banger, do a 5 spd swap and possible supercharge I am way over the cost of a V6 conversion??? I am not looking for gobs more power, just enough to make pulling mountains and highway driving a little more enjoyable....the more pleasant the ride, the more likely that my wife will be open to longer trips in the B.

Any input would be great, as I would like to start collecting parts for the conversion if I am going to do it.

Bill, you will a lot of different reasons or suggestions. First is your disappearing oil pressure. My 4 cylinder had plenty of oil pressure and didnt burn oil at 87K. If you have 69K that engine should be good.

I have a 3.4 V6 on my engine stand. I wanted more reliability, more power, better gas mileage and a 5 speed in my car. I intend to use it as my island car and daily driver when finished. Those were my reasons.

You can also look at supercharging, using a turbo, or Moss sells an EFI kit for your engine. All good choices too. OD would also be an easy option to install. Any engine conversion is bound to be more expensive than keeping the stock engine. IMHO.

This is a mixed message, but I have experience going both of these directions. I have rebuilt B's, fuel injected them, and also made a few MGB V6's.

While the cost of a complete rebuild may be that high, a 'freshen' of the motor can usually give results almost (if not) as good as a complete rebuild and much less expensively. It should take the weekend mechanic a day (or two at the most) to:

Replace the rod and main bearings(all but one)
Re-ring the pistons
Replace oil pump
optional: Get head serviced if it needs it.
Replace the timing chain and sprocket.



Bottom line: $200-$400 in parts to freshen the B motor, if the crank isnt scored and the motor doesn't need boring (most don't really need boring until >150K miles). This route is an adventure for the inexperienced hobbyist, but very do-able in about 1 weekend-two at the VERY most for the timid or error prone souls. This can all be done with the motor in the car*, and its a little messy. A day of shop time in an experienced shop is all it should take. (I'd guess 8 hrs at $75 per hour-$600 plus parts)

* you leave one main alone, since you cant get to it without lifting the motor.


*****You might consider fuel injecting the B.*****************

If I had done the work I've done on fuel injection first, I probably would never have done a V6 conversion. Fuel injection using the conversion route I developed has made my MGB car faster, more reliable, and better on gas than the carb setups (Weber Downdraft or twin 1.5 SU). (See my postings here on this topic). It cost me less than $500 to fuel inject the car.


A 2.8 V6 in a B makes it a quite strong car-even a tired 2.8 is a great improvement over a tweaked fresh B motor. It is far more powerful and driveable a car with this motor&trans than any common 4 banger B. I did a TBI injected 2.8 from an S10 and retained the fuel injection. It was a pretty painless swap, and not that expensive. ($500 for the s10, $200 for the tranny swap (dont use s10 tranny-sell it and get the v6 tranny, but use the s10 bell housing and flywheel. This route avoids needing an HTOB , and so maintanence is easier and cost is less). The fuel injection is easy to retain, and it's free. I recommend the exhaust manifold from British car conversions. I made my own tranny mount and engine mounts. (I will give you patterns if want to make your own). I used a driveshaft adapter from British car conversions,too. Local shop for pipes and mufflers. Run an extra heavy ground wire from the battery to the engine. Ground everything to it (car electricals, computer, etc.).

approx cost: 500 s10 (shabby truck, but low miles)
200 tranny swap
150 driveshaft adapt
300 exhaust manifold, etc.
100 steel for mounts, and motor mounts
60 Hi pressure inline fuel pump
20 tubing and fittings for clutch
100 odds and ends

I spent more on the paint job than that.




A v6 conversion takes a more money and time than doing a simple freshed to a B motor, anywhere from about $1500 total to $7500, depending on choices of motor and details.
notes:
I made my own brackets, etc for the alternator
I personally think using a a carb is a waste of money, since the motors were set up for fuel injection, and they run much better that way. (lotsa info and threads on that topic). Seems a little odd to retrofit museum grade technology in the case where You're trying for inprovements. Carb probably costs 15-30 HP (see the GM specs) and it is less reliable than the fuel injection which comes free with a donor car/truck.

The thing that scares me about supercharging the B or even doing a performance rebuild is that it is pushing the higher end of what the engine is capable of while even a carbed V6 has a starting hp rating higher than the 4 makes. I would rather have an engine that works less hard for the same output...seems like engines tend to last longer that way.

I am still considering FI if I do the V6 swap, but I don't mind carbs. I guess it will depend on what I can come across as a donor vehicle. With the lack of rust in this area vehicles tend to be driven until they die, so finding low milage donors can be tough, at least at a reasonable price...

I was pretty set on the V6 conversion but I don't want to get in over my head with cost....time I'm not to worried about because I would start at the end of the driving season and hopefully be done by the beginning of the next..could be a good 4-4 1/2 months.

Hell, maybe I should find another B and have one of each. Anyone know the winning lottery numbers??

I agree with your reticence to tweak the B motor.There isn't all that much to get out of a B motor-less than 30% improvement unless you have a key to Fort Knox. Takes a lot of money per HP of improvement and can cost reliability. (Read tweaking a B motor in a daily driver is a waste of money).

************* HOWEVER, IMHO,*******************

Retrofit fuel injection and computer control spark adds about 20% in HP and increases reliability. Cost is less than $500 DIY or about $2500 for someone else to do it for you.


The BV6 conversion is really cool and a great route to a good performing car. I've done a few.
Final cost in time and effort is similar to the cost of a Miata (unless you do your homework, find a good donor, and make some of your own parts). I like my BV6 much better than a Miata, and I'm too cheap for a BMW Z3, which is the next step up. A sweet Z3 is like a Modern and gentrified B--but not cheap.
Then, again, nothing is......

Several customers of ours had a B with a Supercharger, now, the own a V6.
FI; TBI is a old technology, Carburetors, regardless of what many people may think that they are old, a well tune carb runs just as good. Carburetor shops are still in in business and doing well in the modified world.
TBI is the next thing and yes it is simple and performs great. FI are limited to the camshaft thus hp and torque increases are limited and that is a fact.

I would recomend you by a crate engine, you will save money in the long run. A long block 3.4 cost is $1750 to $2000 You can buy a used engine with low miles, but is a gamble, you just don't know what you get until......

We have kits and our new exhaust headers, pulleys and just about anything you need to convert your B to a V6.

My advice is for you to plan your V6 project. I have a spread sheet that can help you to plan your cost and parts that are needed for your project. E-mail me if you would like to have the list.

sorry for the simpleton response but maybe a new oil pump and a tune up?

myred64mgb Wrote:

I noticed that the 3.4 crate engine on the GM site says for auto trans applications only. Is there a way to modify for a T5?? If not what is another good place for a crate motor??

Bill G,
Thanks for the offer on the list. I will be emailing you to get a copy.

Thanks all for everyones input so far!! I'm sure I will think up more questions soon...

Bill,

You can ignore the idea that the crate motor is only for the carb'ed automatic only for the S10. This is because it comes with a flexplate, not a flywheel. It also comes with a cam for the carb, not for FI. Its also meant as a direct drop in for early S10s which required a different pedal arrangement to convert to a hydraulic pedal.

I have placed hydralics in my 1982 S10 3.4L SFI so that blows that out of the water (not that it has anything to do with the MG conversion)

I have built a few crate motors for the T5 for the MGB- that blows that out of the water.

Many people including our shop has built crate motors into SFI systems along with TBI and MPFI systems, so that blows that thought away.


Now bolting the motor in an aircraft thats going to be using a wet sump and flying loops- I quite doubt that would be possible although small powerful light marine applications could be done I bet!

-BMC.