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68BULLITTbuilder Avatar
Commack, NY, USA   USA
1948 MG TC "Annabelle"
1956 MG MGA 1500 "Claire"
I've got a '48 TC with the original engine and gearbox. As some on here may already know and those over on the Volvo powered MG forum I'm planning on repowering my TC with a Volvo B18. It's not that there's anything wrong with my XPAG, I've rebuilt it slightly over stock as it was already over bored. However, even with all that, I'd like a bit more than what an XPAG can offer at a much lower cost. So with that in mind I'm using the B18 engine and M40 gearbox. I'm posting here for anyone considering the swap or repowering their TC. There's already quite a bit of information on swapping out the XPAG/XPEG in a TD TF and the swap is a bit different. Since I don't own a TD or TF this will not likely help any of those owners.

The first major thing that I'd like to point out is that this is not going to be some hack job. In fact, the way I have researched and planned there will be NO disruption to anything on the TC whatsoever. I want it to be that if I so chose on any given weekend I can swap out the Volvo power and go back to the XPAG, for a show or what have you. The original engine mounts will be reused with custom mount brackets that bolt to the engine. The gearbox which just like the engine looks VERY similar to its MG counterpart. In fact the gearbox only needs an adapter plate and I can also use the TC gearbox mounts. The driveshaft bolts right on to the gearbox, no modification required. The TC's generator will be used, swapped to the correct side, and as I've already determined there will be less than 4% error reading at the tachometer from the differences in the MG to the Volvo. This will allow me to use the stock TC control box. The thermostat housing will be customized in order to use the stock TC hump hose, water pump plumbing as well to use the stock lower radiator hose. I'll make my own threaded adapters for the oil temp, water temp, and oil pressure gauges. The intake manifold too will be adapted to fit inside the TC side bonnet panel. I'll be using a B18 header made to fit around the steering column, the rest of the exhaust will be fabricated out of stainless. The clutch will be actuated via the original chain configuration with a bell crank to span under the gearbox. Even the Volvo speedo cable will mate right onto the Jaeger gauge.

I'm not the first to attempt this swap but I may be a little more thorough in the fit and finish of the project to give more power and torque with greater reliability. I will be following up in the upcoming weeks and months as I progress with the swap with information and pictures. I have a few more bits in mind in making the Volvo powertrain look like they belong under the bonnet but I can't reveal all my secrets at the outset.

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68BULLITTbuilder Avatar
Commack, NY, USA   USA
1948 MG TC "Annabelle"
1956 MG MGA 1500 "Claire"
Well, progress has been slow, well more like nonexistent as other things have gotten in the way and the weather hasn't been very cooperative. But, I have been able to get a few more parts. Namely, a pair of SU H6 carburetors that will use the TC's original connecting linkage, choke linkage, slow running arm, and float bowls. These will have the SM needles, which should give me some pretty satisfactory performance. For the engine itself, I've replaced the original fiber cam gear with an aluminum gear, and am replacing the original cam with a "D" grind for more performance throughout the range. The lifters too are being changed out for new parts as well. Other than gaskets, a good cleaning and paint that's it for the engine internals. After all that's completed, I'll begin mocking up the engine and gearbox in place for some nice custom mounts from the engine to the stock TC chassis side mounts. The original bolts, rubbers will also be used.

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BMC Avatar
BMC Gold Member Brian Mc Cullough
Minneapolis, Minnesota, USA   USA
With an engine with that much power in a TC that weighs so little, you could run a 3.7 or 3.5:1 rear end and be fine. The TC has something around a 4.88 stock. Are you planning on changing that out as well?

I am a bit sceptical of not changing any sheetmetal as I have seen other conversions and think it may be more involved than the initial look gives, but waiting to hear about what you find. I believe the Volvo engine is slightly longer/taller than the XPAG engine is.

-BMC.


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68BULLITTbuilder Avatar
Commack, NY, USA   USA
1948 MG TC "Annabelle"
1956 MG MGA 1500 "Claire"
Brian, I still have my original 5.125 as of right now in the axle. However I picked up a Morris 1000 4.55 diff. that I'm planning on running at some point. I've also got a slightly taller tire, 4.75/5.00x19 so that's helping a bit too about 7.5% faster on all gears. Height wise they are about the same, the length is about 1/2" longer on the volvo. Width wise, the engines are the same. The manifold modification is the key to keeping the bonnet sides intact. I absolutely will not cut my bonnet. Now, if I had someone else's I'd modify it as I think it would look really cool with a tear drop on the side and metal gauze bubble to catch the air. But since I don't have a spare, the manifold will be cut and reclocked to more closely match the XPAG intake. Exhaust wise, that'll all be custom fabricated. Long tube, equal length headers bolted to a 2" exhaust with resonator in the same spot and dimension as the TC's original muffler.
I've read the only documented swap with a TC, and worked out the bugs to give this conversion a bit more fit and finish. Most of the guys doing this swap have TD's or TF's.

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plus4moggie Tom Lange
Bar Harbor, ME, USA   USA
My feeling is that the engine power is not the limiting factor on a TC. If you increase the engine power you will certainly need to do more to the brakes than just go to Alfin drums, the easiest up-grade. The steering and suspension are, I think, going to be the real limiters in such a swap, and then you are really getting pretty far from a TC's character. TC race cars move farther and farther from being TCs as their balance between power and performance is disturbed. They need stiffening in the chassis, 16" wires, and a multitude of other modificatikons to tighten things up. Probably the best-driving TC I ever saw was one in California in the early 70's that had received a TD rack and pinion steering transplant - and believe me, it took the guy more than a year to engineer just THAT in place!

A stock TC with a B18B's 100HP is not going to be a very satisfactory drive, IMHO.

Tom Lange
MGT Repair

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