The "B" is now riding on new rear leafs, and I've put enough miles on it since doing that(~200-300, not sure exactly since the odometer doesn't work) that I feel pretty confident it's not going to fall apart on me.
First of all, it's astounding how much the old springs had sagged over the years. Of course, this was a mandatory repair since one of the springs was broken, but none-the-less the rear end sat fairly level. Setting an old spring next to a new one showed that the arch had collapsed by ~1", and the old springs were actually about an inch and a half longer(eye to eye) than the replacements. The rear of the car does sit higher in the back by about an inch and a half, but it's not obnoxious by any means and the overall effect on the handling is dramatic. Unfortunately, the steering wheel is now off center. I suspect that the tie rods were adjusted to compensate for the broken spring, but to check that I need to get the front end off the ground, center the wheels, and count the turns from center to lock in each direction. If it's even, I'll have to pull the wheel to center it(assuming I rule everthing else out) although this is a job I dread doing. If the wheel is not even(i.e 1.3 turns in one direction and 1.2 in the other) its indicative that I'll need to need to center it with the tie rods-an overall much easier job.
Needless to say, the car also got all new rubber in the back since I had to remove it anyway(and it added all of about $15 to the repair) as well as a fair bit of replacement hardware. Some of the old hardware had to be cut to get it off, and I overall felt better using new parts on this very critical part of the car.
Here's a before and after of the wheel well-please excuse the poor quality of the photo
And a sort of interesting photo of the car with one spring replaced
The next thing to tackle-probably over Thanksgiving weekend-is a full fluid change. The oil change is straighforward albeit supposedly messy thanks to the inverted filter. The PO told me that he changed it "not long ago" but I don't know how long ago that was and it bugs me to see an orange oil filter ever time I open the "bonnet." I'm a big fan of Motorcraft filters, which are generally an upgraded Purolator PureOne(a few more pleats in the filter media) and are a bargain for what they are. I also have to hunt down some Castrol GTX 20w-50, which is the typical recommendation for MGB engines(and other flat-tappet pushrod engines) due to its ZDDP(Zinc) content-most other oils have dramatically reduced or completely eliminated zinc content.
The transmission gets 20w50 also, but fortunately isn't picky about ZDDP and other additives. The big annoyance with this is the location of the dip stick/fill hole, which is only accessible from the passenger footwell. I bought a funnel with a long, flexible extension specifically for the transmission. Fortunately, at least I have rubber floor mats, so spilling a little bit of oil on the passenger floor isn't a huge deal.
The rear end is supposed to get SAE90 hypoid gear oil, which is nearly impossible to find. I have some 80W-90, which is an often-recommended replacement. The fill plug(and possibly the drain plug) is British Pipe Thread, and I'm going to have to custom make a tool to remove it. It's kind of, sort of 1/2" square, and the general suggestion is to get a cheap 1/2" socket adapter and grind it to fit(Harbor Freight ones are ideal for this, as they are not only cheap but also the steel is softer and easier to work). One suggestion I did learn was to remove the fill plug before removing the drain plug, as I don't want to be one of "those guys" who finds himself with an empty differential and no way to refill it.
The clutch hydraulics have a slow leak that I think I've tracked down to the flex hose. I have a replacement, so will probably end up draining all the clutch fluid, installing the new hose, and then refilling with fresh. The brake fluid could stand a change also, but I'll save that for when I do the brakes(which are coming soon).
I've been having issues recently with the dampening mechanism on the carburetors. British SU carburetors are actually quite different in operating principle from the conventional Edelbrok or Holly ones found on many American cars. As air flow through the carb increases, a piston with a needle attached rises that allows more fuel to be aspirated into the air stream. The pistons are damped to improve fuel delivery under certain conditions as well as prevent the engine from "fluttering" when hitting bumps or accelerating rapidly. There is an ongoing debate about what oil to use in them, which cover the whole spectrum of Marvel Mystery Oil or ATF(both about the same weight) all the way up to 90 weight gear oil. Most folks use either 20W50 engine oil or sometimes straight SAE 30. My problem is that the pistons are sometimes slow to fall when falling back down to idle, which will cause the engine to "idle" at 2k+at stoplights while I wait for the pistons to fall(which they will do in 30 seconds or so). I'm going to take apart the upper end of the carburetors, clean them, and reassemble with(probably) fresh 20W50. Whatever is in them now is quite gummy, which again I suspect is the problem.
Finally, I'm slowly working toward doing a full-tune up. I threw some new NGK plugs in it last weekend(BP6ER, which is a favorite of folks on the MG fora)-the big center copper electrode is really a better match for a carburetted engine than the tiny center electrode found on Pt plugs like the ones that were in the car. I need new wires along with a new distributor cap and rotor, as well as to set the timing(I was impeded on this last weekend as I couldn't find the timing marks-I've since found them, and do have a timing light to make full use of them). Once all that's done, I just need to get the carbs balanced and adjusted, although the spark plugs tell me that they're already quite close-I'd just like to get the "normal" idle down to something more than the current ~1K. I have yet to look at the air filters, but am going to change them anyway. Interestingly enough, the OEM style filter has actually been quite elusive even from specialty suppliers like Moss-instead, everyone wants to sell you the ~$50 each K&N filters(which dispense with the stock air supply set up entirely and just hang off the side of the carburetor). Fortunately, Napa actually carries the correct, original style paper filters and for a very reasonable price.
On a final note, my parents have been quite bothered by the fact that I currently don't even have a top on the car, although I do have the frame with the poor condition original vinyl top. They really want to buy me one for Christmas, so I've speced out a reasonably priced Robbins-brand top of higher quality vinyl than the original and also has a zip out rear window(better ventilation on hot days). I'll likely end up going with tan, as I think it will look nice with the BRG body(and photos I've seen of the combination look quite good). A local auto uphostery shop will install it for a reasonable price-I don't want to fit a top myself.
