MG Sports Cars

I found a way to put off building a vibratory polisher to shine up the headers. The labor was one thing, but the ceramic tumbling media was going to cost a couple grand, I don't have that kind of money to spend on it, and pea gravel wasn't looking like an acceptable substitute. So I found a shop that would polish them for me and shipped them off. Hopefully they'll be back next week sometime. In the meantime I've begun work on the inlet scoop. The IAC valve isn't going to work very well on the downstream side of the blower so I pulled that off and will make a blanking plate to replace it, and will locate the IAC on the bottom of the scoop between the butterflies and the air filter. The large pcv breather line will go there as well from the Lucas flame trap, and if I decide I want a throttle blip valve there will be enough room left there for it as well. It's looking like the three butterflies will be very close to 2-1/2" diameter which is pretty big in terms of airflow but visually about right and proportional to the rest of the scoop and the blower. If low throttle openings give me trouble I may have to play with the linkage to get less movement with the first part of the pedal travel.

I will almost assuredly have to cut the hood again. Maybe that won't be too bad though. After the nice way the opening in the Roadmaster's hood came out I think I can do a little better on the edge treatment.

Anyway, I have the bottom of the scoop cut out and bolted to the inlet with a spacer and I've found how to make nice clean large radius bends in the 1/8" aluminum sheet I'm using for it so now I'm just waiting on more supplies to come in. I'll try to get some photos.

JB

Menacing. I almost didn't notice the headers. Looks like they polished out very nicely. Too bad most of them are hidden by the fenders.

Actually Rob, they are not. You're forgetting it's a tilt front end, so when the hood is open it looks about like what you see there.

The headers came out very nice. The place I sent them to did a really good job polishing them and was fair on the price at $50. The shipping ate me up though, $75 there and $55 coming back. (10 of the 75 was insurance) But these always were expensive headers. When I first built them I had $750 in the headers and header mufflers. This time around I couldn't even say but it's probably less than that and I have other things to show for it like the oven and blaster upgrades as well as a new skill so it wasn't that bad. You can see the age in them though. Pockmarks from old rust, tool marks from cleaning, etc. They have character. But I hope the coating will last longer than the last time. If it does I won't have to worry about the next time around.

One thing I did was to install bungs for individual EGT sensors. But the sensors themselves are about $55 each so they won't get installed right away. I think they are a good idea, but buying wheels put them off the radar for awhile. Gotta have wheels though, if it don't roll it can't go anywhere. These headers are 1-1/2" diameter long tube (38") equal length within 1/8" on all 8 tubes and they really lit a fire under my high revving Buick 215 and the blown Olds 215. I built them expecting to end up with a 5L BOPR but I think they will do just fine on the 340. I cannot overemphasize the benefit of equal length tubes. I know our MGBs don't have room for them but they really wake the engine up.

Menacing... That's a word I'd never thought of but now that you mention it the new scoop does sort of convey that character just based on its size. Really it doesn't look quite that big in real life. I don't know if that will change when the throttle body goes on and with the rest of it boxed in. I have several more significant challenges in finishing it and I'm flying by the seat of the pants but it's coming out pretty good so far. The challenge is making it look good and also work right. But I'm pretty confident of success. One critical part fell into place today, a domed aluminum weld cap which will provide the transition pieces at the upper rear corners. Some trickiness with the filter tray and some lower radius transition pieces and then a bunch of welding, clean up and polishing. The throttle body is an entirely different challenge. If anyone is interested I can take some construction photos of the scoop. I was inspired by Gary Walker's work on the surge tank for the MG-Roadmaster to try some new tricks and up my game and I think it is going to pay off. You know, there are tasks that you do in which you try to work quickly and get done, and then there are some fairly rare opportunities when you take your time, work deliberately and carefully and create artworks. This is one of those opportunities and I'm trying my best to make the most of it.

JB

Here's what I've been working on during the last couple of weeks:







Still have to make the throttle body to go on the front, and the housing needs polished and buffed, but functionally it is complete except for the breather tube fitting. The air filter is a modified K&N for a SBC if I remember correctly, and the IAC valve will mount to a block on the underside. I still have to make an inlet screen for the block.

JB

Looking real nice Jim!
How do you change the air filter?
Cheers
Fred

I think you might have created a bit of a blind spot with that blower! :)

Seriously, amazing fabrication work Jim. Keep the pictures coming. I can't wait to hear it.

Thanks for the kind words.
I can actually see over it so the blind spot is only right in front of the car on the right side, not as bad as it might seem. It's a little taller than the old one (in my avitar) but I honestly never even noticed that one at all. We'll see how it looks when the front end goes back on the car. To clean the filter I just pull down and forward on the frame below the filter (just takes a gentle tug) and then the filter drops out. The throttle body will have a pair of tapered prongs attached to the back side which will wedge the frame upwards to seat it when the TB is attached. Getting that piece made is my winter project this year. There's quite a bit of trickery that goes into the TB and it won't be fast or easy, but at least it'll be the second time through this time and I have a few new things to try. For one, I am going to make the butterflies this time instead of cannibalizing an old carb base. Then I am going to use a pair of bellcranks along with heim joints and polished stainless rod to actuate the shaft and this will let me configure the linkage to get maximum pedal movement at minimum throttle openings and vice-versa. I may even put the TPS on the lower bellcrank if I can get all the play out of the linkage as it would look cleaner and get the same proportional advantage as the gas pedal.

But for now I have polishing and buffing to do, any tips gratefully accepted. Not just the housing but also my stringers for the inner fenders which are stainless and more than a little tedious to buff. I have to get those done next though because they are holding me up on my plans to bend the car, which has to be done before I can hook up the header mufflers. So at this point it's all pretty much brainless labor for awhile. Which is actually a good thing because I'm not up for any more big challenges until I get time to recharge. Maybe sometime between Thanksgiving and Christmas I can get back on the more demanding stuff.

JB

Much closer now. All the major components are in place and it looks pretty complete. Today was a big day for me.



The scoop and stringers are nicely polished and installed. Not perfect, but I was always more interested in results than appearance anyway.



This is the third major build for this car and finally, I am completing the car I've always wanted. There is really nothing on the car I would change even if time and money were no object. Well, maybe spruce up the interior and paint a little, but it's very comfortable the way it is so maybe not. Maybe run the exhaust out the rear and do the planned upgrade on the brakes sometime but those are pretty minor compared to all the rest. I'm really looking forward to driving this car.

Still a lot of smaller jobs to do, and one very particular milling job. But the worst is behind me now.

JB

Today I managed to cut out the blanks to make the throttle plates. That job was sandwiched in between making upgrade parts for the milling machine. (It's the Blackwood way... fix or make a machine so you can do the job. Usually the fixing takes 3 times what the job does.) Those blanks will be placed into a custom angle jig (yet to be made) and have the edges turned on the lathe so that they match the bores in the throttle body when at a small angle like any other throttle. It's exacting work, but a good job on that means a nice low idle will be possible. Of course I have to decide which comes first, the plates or the bores. A lot of thought goes into making a throttle body before even the first chips can be made, and parts like shaft bearings have to be on hand before determining final dimensions. Getting ever closer though, the plan is pretty complete.

I also moved the car to the lift, ordered a box of 5/8 x 7" tapcons and found a length of 3 x 3" square tube to run across the sills so hopefully I'll be ready to bend the car in another day or two. I still haven't decided whether to remove the perforated rockers first, but I probably will. I'll probably sink the tapcons tomorrow and set up the rigging, then I have a bunch of very careful measuring and comparing to do before giving it the first shot. It should be very handy having the '74 in the shed for comparison.

JB

Amazing work Jim!!!!

Thanks Chris, but it's nothing anyone couldn't do with the right tools and know how. Bad thing is, it tends to take years if not decades to get either. But I've paid my dues, so now occasionally I get to play. That's the payoff for all the fixing and making mentioned above.

Today's work is done, tomorrow will be spent with family. Somewhere along the line I'll try to finish the rigging and measurements and then maybe I'll see if Steve would like to assist in the bending. Wouldn't hurt a bit to have an extra set of eyes and ears and he should be here by mid-afternoon on Sunday. We'll see what happens when you intentionally try to bend an MGB bodyshell. I dare say that it's unlikely anybody has ever tried it before.

JB

Well what a surprise. I knew the MGB body tub was stout, but I really had no idea. By my calculations we applied something in excess of 11,000 lbs to the inner sill on the passenger's side and the door opening flexed less than 1/4", and then sprang back when the pressure was removed. I even tried jumping up and down on the opposite sill to apply leverage across the body but it wasn't giving in the least, and felt as solid as if it were under no pressure at all.Sort of a bitter-sweet moment to realize just how strong that structure is, but that I'm stuck with the shape it is in until the next paint job. That could be a very long time. Oh well, on to more important matters.

JB



Edited 1 time(s). Last edit at 11/21/2011 02:15PM by BlownMGB-V8.

Did you take pictures of the rig you used when you were bendinng the car?

Yes Jim B., could you ? I'll need to do this several times on the Healey, but I need a good plan on the rigging. Thanks, roverman.

I'm sorry guys I didn't even think to take a photo. Steve came in and I wanted to do the deed and get it off the lift so we could change the oil in the Roadmaster. But it was a pretty simple rig so I'll try to explain it.

I put the car on the 2 post lift in the normal fashion except that I used 1 ft long 2x4 blocking between the pads and the car, under the frame rails at the front and under the spring hangers at the rear. Then blocking up with 3x3x12" blocks on the inside sills so that a 3x3 square tube across the sills cleared the tunnel by an inch or so. On the off side I placed another square tube under the lift arms parallel with the car and chained it to the cross tube using an axle strap and on the side to be bent used a second strap and chained the end of the beam to two 5/8 x 6" large tapcons embedded in the shop floor, using 2" x 1/8" strap folded up around the head to even the pull with a 1/2" bolt through the ends and the chain in the center.

I used the lift to apply force to the sill by raising it in the usual manner and taking measurements as force was applied. We had about 1/4" of initial deflection at the top of the door opening front to rear but then upon attempting to lift further the deflection stopped and the pressure relief bypassed the hydraulic fluid. At that point I went around to the off side and figuring the distance from the lift points to the anchor point and from the lift points to the opposite sill would give me some significant force multiplication, I jumped up and down on the off side sill. It just laughed at me.

Because there is a healthy steel cable in tension equalizing lift force in the lift from side to side, the force of the cylinder on the off side transferred across to the working side, applying the full force of the lift which has a 9000 lb capacity (Rotary brand lift from a Ford dealership). I figured about a 10:1 ratio for jumping on the opposite sill so added another ton or so.

JB

Here's a shot of the Idle Air Control valve and mounting:



The IAC is late M'tang and is a large diameter valve compared to earlier units so I'm hoping it is also quicker reacting. We'll see.The mount includes a stainless breather screen to keep out bugs and large debris. Flow is then through the standard air inlet filter. I had to move it up here because the earlier location on the plenum is subject to positive pressure which would have really complicated tuning. This location, nicely tucked away under the inlet scoop, is much better.

JB

A bit more eye candy:



This PCV system uses the British format with an orifice breather on the opposite corner of the engine. The stainless line was sand packed and formed using a custom fabricated bender. It draws filtered air through the engine via the orifice and then into the blower inlet under vacuum under normal conditions (also assisting in sealing small oil seepages) and vents blowby directly to the inlet under WOT. The inner diameter of the tube is about 9/16". The large canister below the tube is the stock Rover flame trap which prevents crankcase explosion in the event of a backfire and also separates oil vapors and droplets and returns them to the rocker box.

JB



Edited 1 time(s). Last edit at 11/30/2011 10:50AM by BlownMGB-V8.

Beautiful work Jim, you continue to impress me with your fabrication skills on this project.

Jim, where did you get the rubber connections for your PCV lines, especially the one that connects to the valve cover breather? I think I would like do to the same thing with mine and do away with the ugly rubber hoses that I have right now.

Looks fantastic!!!!