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1936 MG TA Carburettor rebuild.
A friend has a 1936 TA and I volunteered to rebuild th carburettors. This is a short pictorial view of the job.
The stripped carbs in a bowl of petrol
Some of the parts taken off, the cork glands soaking in oil and one plastic heat sheild block. One of the SU kits had only one small gland the other is on it's way, the supplier (NTG - highly recommended) had only one plastic block in stock. It's for an MGA. I have longer bolts/studs to fit to the manifold.
An out of focus picture of teh SU overhaul kit in its plastic bag.
The piston on the right has been cleaned, the left hasn't. The picture doesn't show just how black these pre-war brass pistons were.
I've rebuilt many SU carbs but never seen baked on oil/petrol like this. It took a lot of scrubbing with a wire brush to get it clean
The other side
One side cleaned......
.... and the other side.
Most of the parts after cleaning
A slightly out of focus picture of the brass bits after cleaning on the wire wheel. They were black before cleaning.
Some of the throttle spindle parts after cleaning. They could do with a dip in an acid bath..... I know I'll use some Coca Cola. I'm now waiting for the second plastic heat block, the second cork gland and the 9.5mm reamer to arrive so I can rebuild the carbs.
A Coca Cola bath, best thing for the stuff! It has Phosphic Acid in it which is a good cleaner of metal.
The 9.5mm reamer and a 50mm Whitworth bolt. I will need a 9mm drill with a Morse taper to fit my milling machine and a 70mm setscrew so I can make 2 studs, the bolts will not go into the bottom of the carbs. I will get both the drill and setscrews in the morning and then I can fit the new spindles and rebuild one carb. The other will have to wait until I get the other cork gland which is due after 1600 tomorrow (Monday 14th Oct.) It will have to soak in oil for 24 hours so I'll finish them off on Wednesday.
I drilled, reamed and fitted the new bushes into the front carb then built the jets and floats etc. Only problem was I got so engrossed in it I forget to take any pictures.
So, this morning (Tues. 15/10/19) I did the other one. I'm not very happy with this one because the spindle is very tight but I'm hoping it won't stick open. Of coure it will free off in use. I have had to order 2 new throttle stops as the originals will not come off the shafts. I guess after 83 years they've fused together. Then I open the second carb kit and they've left the pack with the two cork glands out so I've added them to the throttle stops ordered from Burlen the SU carb people. I'll finish the second carb tomorrow when they arrive.
The carb body being drilled to take the teflon coated bush.
An out of focus picture of the butterfly fitted to the spindle
Another out of focus picture, this time of the throttle wide open. You can see the split in the threaded end of the screw which will be bent over slightly to stop the screw coming out and being eaten by the engine.
The front carb fully assembled. The jet has been aligned by ensuring the piston drops with a thump when the adjusting nut is fullly up. This is done by have the large nut slightly loose and tapping the jet to cenralise it then tighten the nut. The starting point for the adjustment is, if my memory is correct, 7 flats.
The other side of the carb.
The two throttle stops that will not come off the shafts.
Nearly there. I'll leave the drilling of the throttle stops until I refit the carbs as I can't remember where the throttle arm is. It'll only take a few minutes and better safe than sorry.
The new throttle stops arrived but the one with the arm hasn't got the adjusting arm drilled or tapped. I rang SU and decided to return it for one that is tapped or they will drill and tap the first one. I posted it back on 17th October. I checked this morning (22/10) but they say they haven't received it. They are trying to sort it out and have said they'll ring me back. In the mean time I've drilled the one I have, cut the spindles to the correct lengths and fitted the carbs to the manifold with the longer studs and heat block. All that remains now is to fit the throttle stop with the arm (for the throttle lever that comes through the bulkhead) and refit the carbs.
Carbs from all angles and the space on the spindle for the throttle stop with arm.
This is the arm. The horizontal arm with the threaded hole for the adjusting screw was blank on the one they sent.
New arm, drilled and tapped has been fitted. The carbs are now back on the car. We had trouble getting fuel to them so, in the end, I primed the pump by sticking the suction pipe in a bowl of petrol. That did it. By this time I was frozen so I'm returning next week to get the car started and adjust the carbs.