Fitting an XPAW engine in a TA

2 Mar

One big fault with the MPJG engine is the cylinder head. The siamesed central exhaust port can cause the head to crack athwartships in this area, especially if the engine has been thrashed.

Of my five TAs I am lucky that only one has a cracked head…. and it would be my Tickford!

What happens then is oil from the rockers gets ingested into the cooling system. An easy fix you say. Not so. I do not know anyone who has succeeded in making a permanent repair.

To fix the problem I decided to fit an XPAW engine from a Wolseley 4/44. The XPAW is the final rendition of the XPA engines similar to that fitted to the MG TF and YB. These engines are easy to get but will not fit into a TA without some changes. They have the later 8 inch dry clutch, which fortunately the MG YB is fitted. The YB also has a sump of similar shape to the TA and the YB clutch housing was just what I needed as I wanted to use the TA gearbox.

Both these items Tony Slattery was able to supply. Other essential items needed are a TC front mounting plate and TC intake and exhaust manifolds. These were supplied by Barry Walker.

I planned to use the TA dynamo and carbs so I could use the TA air inlet manifold and air cleaner.

One major job was matching the TA gearbox input shaft to the XPAW clutch. The Wolseley gearbox input shaft was cut off as was the TA gearbox input shaft. Then the Wolseley shaft was welded onto the TA ‘box shaft. This needed careful measuring but it worked. The other thing was the clutch release mechanism. I had a spare VA clutch cross shaft and fork etc. This was a stronger affair than the YB shaft. I had it extended on the off side to align with the TA clutch pedal. Also, bigger shaft bearings were fitted.

All this went together nicely and fitted exactly into the TA engine bay using the TA clutch release rod etc. I had to change the rev counter drive gearbox on the rear of the dynamo for one with a shorter drive to clear the distributor. There is not much spare room around these items as the Wolseley distributor has a vacuum advance which gets in the way

Another problem was the bonnet bulge to clear the dynamo. On the XPAW the dynamo is lower than on the TA engine but you can’t just lower the bulge because of the bonnet catch being in the way. We ended up turning the bulge vertical. Looks a bit odd. The TC has a much smaller bulge but how it clears the dynamo when at full stretch beats me.

The TA carbs need distance pieces fitted so the float chambers will clear the manifold studs. This works OK as with a slight bend you can still use the TA rad stay. Also, the fuel pipe from the pump to the carbs is a bit short. You need a 14″ pipe. The other big problem was connecting the XPAW thermostat housing outlet to the radiator. As I wished to use the modern thermostat I had a new 1.5″ top tank outlet fitted as far to the near side as possible. I had the old 2.25″ outlet sealed off but still there. Then a rad hose with a 90ª bend made the connection. Simple.

Other items needed are a TC front exhaust pipe and a TC steering box chassis bracket. NTG supplied both these. I was disappointed with the exhaust pipe flange stud holes. At both ends they were not quite correctly drilled and needed a lot of filing The other thing needed is a solenoid to operate the starter, preferably with a pushbutton. I had a couple of Wolseley 18/85 pushbuttons and fitted one in the TA dash panel in lieu of the old starter cable. So now I have virtually a TB Tickford with a more modern engine than the original TB had.

Going back to the steering box bracket, I found the TC one of no use. It was just a heavier version of the TA bracket and the mounting holes were different.

Above and below the TC steering box bracket (silver) and the TA bracket (pictures by kind permission of Stewart Penfound).

I decided to modify the TA bracket by bolting two extension pieces to the offside of each box mounting lug. This moved the box up, forward and to the right so the column would clear the starter and clutch housing.

Things are so tight in this area it was necessary to assemble the bracket onto the box before mounting the whole lot onto the chassis. I had to remove the plate where the column goes through the bulkhead as the raised column fouled this when mounted on the under-dash bracket. Just as well the Tickford has adjustable steering wheel splines.

I have fitted TC/TD carb needles and am using NGK BR5ES plugs. Both the fuel hose and carb needles supplied by Pete at MG Octagon CC.

Two other items I should mention are moving the dipstick to the offside of the engine and fitting a TC tappet cover and breather pipe. There is a flat provided for the dipstick on the offside. It may be possible to use the Wolseley tappet cover but the breather location and attachment may need looking at.

I have now had the car on the road and the installation appears to be working OK.

This paragraph is for Mike Sherrell. This is how I prime the oil pump and expel air from an engine before initial start-up. I use an old garden weed sprayer. Put 3 or 4 pints of running-in oil into the sprayer and connect the tube onto the oil gallery via a suitable plug hole and various fittings. Pump up the pressure and go and have a cup of tea. Come back, pump up the pressure again and give the engine a few turns with the crank-handle. Fill the sump with oil via the rocker cover to the correct level. Then disconnect the sprayer, carefully replace the gallery plug, leap behind the wheel and fire up. Instant oil pressure. I have done all my new engines like this and never had a failure.

Gary Wall, Martinborough, New Zealand

Ed’s note: I corresponded with Stewart Penfound on the subject of the steering box bracket and with his agreement I’m publishing what he said:

I initially thought using a TC steering bracket was the answer but as you can see, one of the mounting holes is spaced differently, which means it would have to be drilled to fit. Even then, it wouldn’t bring the steering column far enough forward and upwards to enable it to miss the starter motor. The holes in the TC chassis are, I think, further forward than on the TA, so if a TC bracket was used, three holes would have to be drilled through the chassis (and reinforcing on the inside) and strengthening tubes inserted and welded.

I think the inner reinforcing on the TA chassis didn’t allow for three holes anyway, but my memory is hazy on that one.

I was fortunate to have acquired a home-made bracket that supposedly enabled the column to miss the starter motor, but, as you can see, (pics 03 and 04) I ended up having it extended (and reinforced) to not only get it positioned correctly with regard to the starter motor, but to be able to use the correct holes in the chassis. Even then, I had to fine tune it by inserting an aluminium spacer (about 1mm thick) between the bracket and chassis to give clearance between the bonnet side and the head of the bolt holding the column to the bracket.

In its final position, the steering wheel ended up slightly closer to the dashboard and, because it is now at a slightly different angle, the column fouled the hole in the clamping plate in the foot ramp, making it impossible to fit the rubber gaiter. A new plate was the answer, as you can see (pic05).

I might have over-engineered it, but when I researched it I found that although hundreds of TAs have XPAG engines fitted, no-one had ever written down how they overcame the problem!

I have heard of people using TC brackets but the torque from turning the steering wheel is so great that if the chassis wasn’t reinforced it would flex so much it would be positively dangerous. (When I first fitted my reconstructed bracket, it bent noticeably when turning the steering wheel, which prompted me to have a reinforcing web welded on). Another solution I’ve seen is to cut a slot in the back of the steering column’s outer sleeve where it touches the starter motor, and I’ve also seen one where the TA bracket was retained and the column was jammed so tightly against the starter motor that the engine couldn’t move at all on its front mountings.”

(Pics 06 and 07 show the final fitting)

Pics 03 & 04 – Stewart’s acquired home-made bracket, which he modified and strengthened.

Pic 05 – new and old clamping plate.

Pics 06 & 07 showing final fitting.

Ed’s further note: Perhaps this is an opportune moment to remind readers that when modifications to the standard arrangement have been carried out, it is most definitely advisable to notify your insurance provider with full details of the modification(s).

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