Carburetors

PROJECT 51: Carburetors. The MG (and many other British sports cars of the period) used a pair of side-draft carburetors made by SU. They were (and are) notoriously finicky to get set up and balanced, and to the American mind, are far more complex than a carburetor needs to be. There are aftermarket kits that replace them with a "normal" downdraft carb, but obviously, I can't go there. So, I am rebuilding the 69-year-old originals.

Over time (especially when the car isn't even started for many years) the seals and gaskets dry out and crack, but there aren't too many moving parts to wear out. The major wear items are the fuel-metering needle and the throttle-plate shaft.

The metering needle is a long, small diameter pin that is slightly tapered from one end to the other. It fits inside a jet body with a hole that is only a tiny bit larger than the big end of the pin. This is where the fuel is "metered" into the intake air. The farther the tapered pin is drawn out of the jet, the more fuel is delivered.

Surprisingly, the pins and jets in my carbs had been adjusted properly and showed almost no signs of wear. But since the rebuild kits came with new jets, I decided to replace the old needles, as well. The "universal" kit does not come with needles because there are "standard," "lean," and "rich" versions to choose from.

The throttle-plate shafts were a different story. Both the shafts and the holes in the throttle bodies in which they turn showed plenty of wear! There is supposed to be about .001" of clearance between the shaft and the hole; mine had more than .008". That creates a leak-path for air that makes setting a smooth idle almost impossible.

The kits come with new shafts and a set of bushings to make the holes the right size. Installing the bushings requires machining both sides of the throttle body castings (you can't do both from one side), and while I was figuring out how I was going to fixture the parts in my mill to get both bushings perfectly in line, I did some Internet searching to see what others might have come up with.

Several times I saw the name "Bob Johnson in Claremore, OK" pop up as being THE guy to send your SU carbs to if you wanted them rebuilt. I e-mailed him and asked what he would charge to just install the bushings. He replied $50 total for two bushings in both bodies. No brainer! The bodies and bushings were in the mail the next morning.

While waiting for those parts to come back, I cleaned and polished the rest of the components, and I also sent the exhaust manifold out to be ceramic coated. It should never rust or discolor, again.

The assembly of the carbs is intricate and a bit complicated, and the instructions that came with the rebuild kits are not the best I've ever seen. Because the kits will service several different models of SU carbs, there are some extra washers and gaskets … and they don't bother to tell you that. There is also an illustration that shows a "piston return spring" that was missing from both of my carbs. While cursing Brutus, yet again, I did some digging on the Internet, and I found that that spring wasn't used in the early TD carbs. (While Brutus was blameless for the spring, he did manage to lose some of the original screws and replaced them with whatever he could find.)

Between the rebuild-kit instructions, the photos that I took during disassembly, and some better cut-away and exploded views from the Internet, I was able fit all the puzzle pieces back together to factory specs.

I mounted the finished carbs and the air-cleaner to the engine for photos, but they will come back off before the engine gets mounted in the frame, to make sure they don't get damaged.

Before the engine removed from the car.

I took plenty of before photos.

Before and after polishing.

Rebuild kits and the carb parts. (Throttle bodies are at the shop.)

After with ceramic-coated exhaust manifold.

Shown with the restored air cleaner.

Off to Paint

PROJECT 51: Off to paint. I finally have the major body parts off to the paint shop. Or, more correctly, "another" paint shop.
Most body and paint shops are set up to work on whole cars, so when I approached them with the idea of bringing in all the separate body parts most of them were scared off. One shop I found was interested and quoted me a fair price, but when I visited, I found out that they didn't have a paint booth; they painted outside "on calm days"! (I can only imagine what the neighbors' cars look like from the drifting overspray!)
Another wanted to "take it to the next level" with a concourse-quality paint job at a price that would have exceeded the entire cost of the restoration, including purchasing the car to begin with.
I finally found a shop that would take my parts a few at a time, and fit them in between their regular collision-repair jobs, and at a reasonable price. I dropped off the fenders, doors, and running boards to get started. Two months later, no progress had been made, and I talked with the owner about getting a schedule. He told me that they were too busy with their collision work, which needed to be turned around quickly, and that it might be six months or more before he could get to my stuff. (I'm not sure how he knew that they wouldn't STILL be too busy in six months.) I decided to keep looking, and when I went to pick up the parts, I found them sitting outdoors on a rack with a dozen other piece-parts, some of which looked like they had been there a lot longer than two months. (I didn't bother to ask the owner if he had an uncle or something named Brutus.)
I asked some of the local car guys and gals for recommendations in the area, and was surprised at a name that came up more than once. A Maaco shop in Mesa.
I'm aware that some of you have just had a shiver run down your spine, but when I went out to talk with them, look at their shop, and at what they were putting out the door, I was more impressed than with Brutus' nephew's place. They were organized, well-staffed, and the quality of their work seemed first rate. They weren't deterred by my body-parts requirement, gave me a reasonable estimate based on photos of the parts, and even gave me a turn-around time in weeks, not months.
Bear in mind that I'm looking for a "driver" paint job; one that is more akin to the car's factory finish than something you'd see on the grass at Pebble Beach. If (when) I get a rock chip while out cruising, I'm going to fix it with a tiny dab of paint in the divot; I'm not going to refinish the whole fender.
Now that they have the parts and have seen the spots that will require a little filler here and there, they are going to give me a revised estimate, which is only fair. If it were to double (which I don't expect) it would still be less than a third of Mr. Next-Level's price.
While the body is in paint, and the frame is at media-blasting / powder-coat, I will work on the front and rear suspension and brake assemblies.
I am already getting progress photos from the manager at Maaco! What a difference from the other guys!

Inventory of parts to be painted.
I kept a number of the small parts back that I will paint myself.

The body tub fits perfectly in the truck.

Already making progress!

Bare Bones

PROJECT 51: Bare bones. It only took a day to get all of the suspension and brake parts off of the frame once the body tub was removed. All of the moving parts in the front end were surprisingly tight for a 69-year-old car, so I suspect it was rebuilt sometime in the not-to-distant past. One indicator that Brutus or one of his kin had been there before me was that of the four bolts that hold the rack-and-pinion steering assembly to the frame, two were British Whitworth size, and the other two were American inch size.

In a nod to before we were married, my wife, Diane, tackled the dirty job of scraping the heavy grease off the frame while I disassembled. Back in 1973-74 I did this same level of body-off restoration on a 1946 CJ2A Jeep (which I wish I had kept!) and then-girlfriend Diane helped me the same way.

The stripped frame, the wheels, and a couple of other components are now at ProStrip for media-blasting and powder-coating. There is not too much left to disassemble … but a lot to clean and paint.

Stripped bare and heading for media-blast and powder-coating.

Other items going to media-blast.

Good help is hard to find! My wife, Diane, helping with the dirty work.

So, when you find it, you keep it! My then-girlfriend, Diane in 1974
helping with the dirty work on a Jeep restoration.

1946 CJ2A before.

About nine months later.

Not much left to take apart.

Engine nearly complete.

PROJECT 51: Engine nearly complete. I'm waiting for the exhaust manifold to come back from being ceramic coated, and for some carburetors parts, but aside from those few items, I finally have the engine pretty well assembled.

All of the gaskets were sealed on both sides with high-temp silicone, and the original-style two-piece front crankshaft seal was replaced with a modern one-piece lip seal. This engine should be more free from oil-leaks than the original engineers at MG ever dreamt possible!

In my humble opinion, I believe the MG engine is kind of pretty when it's all cleaned up.

Engine as removed from the car.

Original design two-piece oil seal vs. modern lip seal.
The originals are basically braided rope impregnated
with graphite. The question was never "if" but
"when" they would start leaking.

Bead of silicone sealant on oil pan gasket.
Lip seal is at far left, between the pulley. and the timing chain.

Almost a work of art!

Scuttle Ramp

PROJECT 51: Scuttle Ramp. The bottom third of the firewall on the MG is referred to as the "scuttle ramp." The scuttle of a car is known in America as the cowl, and is the body panel directly under the windshield. Over time, it has come to include the firewall. The scuttle ramp is a separate section of the firewall, angled upward (hence "ramp"), is located right behind the engine block, and has a semicircular opening that fits closely around the bell housing.

When Brutus removed the engine and gearbox from the car he obviously had a great deal of difficulty (See the post about the broken mounting flange on the gearbox and the bent up mounting bracket from 12/11/19). While trying to force the engine/gearbox free, he lifted the pair so high (and so hard!) that he bent the bejeebers out of the edges of the scuttle ramp. He even managed to put a split in the sheet-steel panel!

Over the past several weeks, while waiting for engine parts to come back from the shops, I used the time to get the scuttle ramp back into a more presentable condition.

After degreasing it, I set about straightening and flattening all of the damage that included various dents of unknown origin. First, I used my drill press as an arbor press, and using a 4x4 and a 2x4 I was able to get some of the end-to-end bend out while preserving the crease along the top that is supposed to be there.

I got the rest of the bend out by clamping the top edge of the scuttle between 2x4s in my bench vice, and used a wide pry-bar to lift and bend the metal back into alignment.

I then went to work with a body-work hammer to flatten the dents. Finally, I used a modified pair of Vice-Grips to straighten the curled edges.

I welded the split, after which I used my trusty lead filler to level the area. Spot putty was used over the lead and in several dents to get a smoother surface.

The final step was sandblasting, priming, and painting, and now it's ready to reinstall … sometime in the future.

As removed from the car.
The circular section should be lying flat.

Using my drill press as an arbor press
to flatten part of the bend,

Lifting more of the bends into line with a pry-bar.

Tapping out some of the miscellaneous dents.

Split in the sheet steel panel.

Split held in alignment by a small bar
clamped to the underside.

Spot putty to fill some of the dents.

Modified wide-grip Vice-Grips used to flatten some of the curled edges.

Primed and painted and waiting for installation ,,, sometime in the future.

Oil Filter Upgrade

PROJECT 51: Oil Filter. The MG uses a felt cartridge-type oil filter element that is housed inside of a canister that is bolted to the oil pump. They are readily available (from MG parts-suppliers) but cost about twice what an equivalent modern-day spin-on filter does. They are also very messy to change.

Since I will be changing the oil and filter several times during the break-in period when I get the engine running, a bought a kit that converts the original style filter to a spin-on. But with all of the detail I've put into the looks of the engine, the adapter and filter really looked out of place. So, I painted them both the MG canister color, and even added a reproduction vintage Purolator sticker to the filter. Now, it's not QUITE so glaring that it's not original.

Felt filter element cartridge.

Spin-on filter on another MG.

Original MG canister.

"Disguised" spin-on filter.

Rocker Arm Installation

PROJECT 51: Rocker Arm Assembly Installation. A while ago I posted about rebuilding the rocker arm assembly with new bushings and a new pivot shaft. It has been sitting on the shelf since then, waiting for the engine to be reassembled.

Yesterday I put the new tappets (or lifters) into the block, sitting against the new cam, and then slid the new pushrods through their holes and into the tappets. Lastly, I set the rocker assembly onto the block, and torqued down the bolts. That "lastly" was wishful thinking!

When I backed off the adjusting screws in the rockers to set the .012" valve clearance, I found that they wouldn't retract far enough to even get to "zero" clearance. That meant that all of the valves were being held partially open by the combined height of all of the new and reconditioned parts.

I removed one of the tappets, and measured it against one of the old ones. I found that the new one was .017" taller that the original. That's kind of a wide tolerance for a precision-machined part, but the adjusting screw in the rocker should easily have taken care of that.

I realized that the real problem was that the block and the head had both been machined down (by two different shops) to make them perfectly flat. Neither gave me a report on how much they needed to take off. Then, it occurred to me that Brutus had most likely had the same thing done when he rebuilt the engine. The combination of four machinings dropped the head (and therefore the rockers) down so much that when added to the extra-tall tappets, there was no more adjustment in the screws.

I added shims under the rocker posts, and determined that I needed a minimum of .030" added height to be able t adjust the valve clearance to .012". One option would be to grind the bottom of the tappets to make them shorter, but I am always reluctant to make a change like that, which I can't undo if I don't like the result. Also, it would likely have gone right through the case-hardening on the bottoms of the tappets, leaving them "soft" and subject to wearing out very quickly.

So, I decided to make a set of spacer shims to raise the rocker posts up. I was able to use a piece of 18-gauge steel that I had on hand, which gave me a boost of .048", allowing for a little more adjustability.

The rocker assembly is now torqued in place and the clearance set on all of the valves.

Measuring height of old tappet on the mill.

Shims under rocker post to determine the "boost" required.

Final spacer shims on head.

Final assembly (or is that finally assembled?)