Part Identification and function question

[Lynn Dykgraaf]

Ok Folks,

I've worked on a lot of British cars but have never seen this before. Not sure what to make of it and am looking for some help identifying what the heck this is and why it should be there. In the paperwork that goes back to 1951 the original owner made inquiries into modifications that could be made to enhance performance of the XPAG engine and got several responses including a hand drawn camshaft profile. The only thing that might be a clue as to this part were some notes about modifying the ignition system and a reference to an external condenser.

The top electrical connection goes to the A3 terminal on the control box and the bottom wire heads off into the loom somewhere. Everything got painted black at some point so do not know wire color at the moment. I am pretty early in the understanding this car so am trying to not disturb anything that cannot be undone for the moment.

That's all I got boys. I'm at the mercy of your previous experiences for the moment.

[Steve Simmons]

Electric hot dog cooker? I'd say maybe some kind of ballast resistor except there is only one wire. Is that a spade connector at the back or just part of a bracket like the one below it? Possibly something for RF noise reduction for a CB or radio? Whatever it is, it is nothing that ever came on any M.G.

[Duncan M]

My guess would be a variable (slide) wirewound resistor for an added heater fan. Instead of running the 12V motor at full speed, you could add one of these and adjust it to the desired motor speed, and then wrap it with electrical tape or whatever to keep it at that setting. One speed. Problem with those is that while they do indeed modify the voltage to moderate the fan speed, they often would cause strange amperage consumption. So you might slow down a 4 amp motor with 10 volts, but the overall amp consumption might go up to 6 or 10 amps. A special problem in a car with an 11 amp generator. Mounted where it is because they would often get hot.

Nowadays you would use a Pulse Width Modulator (PWM) to control the fan speed, and full 4A draw would be at full speed, and overall amp draw would go down as voltage turned down.

[Lynn Dykgraaf]

Two comments.

1. There is a second wire coming out from the left side/bottom of the part. Top wire goes to the control box. Bottom wire heads into the loom.

2. This car does have an aftermarket heater mounted under the dash. The hoses you see in front of the art are the water lines to and from that heater. No idea about a fan on the heater yet. There is no obvious switch on the dash.

So much to understand!

Lynn

[Lynn Dykgraaf]

Further inspection shows that their is a third wire in the middle of the part low underneath and follows the path of the bottom or right wire. Not sure how I missed it but it is there.

Lynn

[Ray White]

It may not be connected but I noticed next to the "thingy" you have a horn where a horn wouldn't normally be found; directly above the mousetrap.

[Lynn Dykgraaf]

Yes, there is a horn where there should not be one as well. The one on the foot well is wired in and working, while the one out front is not wired. Just another of the poorly managed things that will need to be corrected over the winter.

Over all the car is in remarkable unrestored condition but there are still quite a few items that were addressed in ways that will need attention. Another two examples just discovered are the clutch return spring attached to the bracket by a single strand of twisted bailing wire. The second is that both carbs are missing the shaft on the oil fill cap that descends into the top of the piston to retard the piston just a moment and richen the mixture when accelerating. I'm assuming this was "speed" modification thought to be a good idea at some time.

Still, I'm having a good time.

Lynn

[Rob Reilly]

I believe that resistor is to control a two-speed heater fan.
Look for a switch with 3 positions (high, low, off).

Some early SU carbs had a brass piston and no shaft and damper on the top cap.
This is from a '38 SS Jaguar. The cap says "Use Bicycle Oil".

[Duncan M]

Lynn, the clutch pedal return spring end probably broke off, and the PO did a repair with baling wire. We like to call something like that "safety wire."

[i.thomson]

It was not some but all. 30s SU carbs had heavy pistons, brass or bronze, without a spring or damper. It was the inertia of the heavy piston which provided the enrichment. The present wisdom has it that after the war metal scarcity led to them being made of aluminium with the spring emulating the missing weight. Some time later this was supplemented by the hydraulic pistn damper.

Ian

[Lynn Dykgraaf]

Hi All,

A few days away from the house so out of touch.

My carbs do in fact have aluminum pistons and no damper or spring. Completely new to me and I was in disbelief at first that this was a possibility. Was able to chat with Joe Curto about this and confirmed several things are in fact correct. I'll be contacting him about the spring issue and if that is needed for aluminum piston SU's of this vintage. Likely a rebuild by Joe as one of the throttle shafts is a bit loose.

No obvious switch for the heater found yet but have not spent a lot of time looking as there have been several other items taking priority. Did find that one of my map lights has been replaced by a cigarette lighter. Also, how common is the under dash panel that hides everything under the dash?

First start of the engine in the morning as all gas tank seeping issued fixed. Fingers crossed on that one anyway. Waiting on correct parts biggest delay in this process. Not that much of an issue on TR3 repairs as so much is easily available.

Thanks for all the commentary. A big help!

Lynn

[Steve Simmons]

I've seen aluminum pistons with weights attached, to make up for the loss of weight. In that case, springs would not be necessary.

[Duncan M]

Lynn, the scuttle mask board to cover things up under the dash was something the car came with, but that nearly everybody will tell you is more trouble than its worth. Most do not use one. Probably originally made of some odd cheap fibre board that would turn to wood stove kindling in a couple years. There are plans for it in the resources section of this site. Click on the MG-TABC banner at top to get the option for "resources" and then hit "technical articles" then it is in the "chassis/body" section.

[Lynn Dykgraaf]

I asked about the under dash panel because my car has one. Looks pretty darn old but in quite good condition. It is in the way but hate to remove it as well even though that would make life easier.

Fired it up today and headed out for first drives. Looks like I have a bit of a water leak from water pump area and brakes are less than impressive. I've had several British cars with all drum brakes and these feel quite a bit less impressive than those cars. Looks like I'll be doing an inspection on those as well. Hoping for just an adjustment issue but they feel pretty wooden with a pull to the right. This winter will see a new water pump, thermostat and gasket, hoses and a radiator refresh or new one.

A second question is about pedal placement. My pedals are tilted to the right and the throttle is quite a bit lower and forward of the brake and clutch. Internet digging really has not provided anything useful. Even with my skinny driving shoes on my right foot is slightly behind the brake. A little sketchy. Thoughts?

Lynn