2013

Monday, 09 December 2013

Vale Martin Hawes

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Yesterday my friend Martin was killed while driving his beloved MGTC.

Martin was a kind and gentle man who gave freely of his time and knowledge. He was quick with an anecdote and was always laughing.

He helped me and taught me a lot. Those familiar with this blog will recognise him in many of the photos. He will be sorely missed.

Marty

Engine and JT5 gearbox installation

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Finally the time has come to put the engine back in. The unknown quantity was the JT5 box, and how much this would complicate the installation.

Prior to starting I measured the JT5 and my Moss box. They are both 66cm long, although this is without the slip yoke fitted into the JT5 box, which adds a minimum of 6cm. The installation instructions warn against trying to install the gearbox with this fitted. It is recommended to attach the yoke to the driveshaft and install them in the tunnel before offering up the gearbox.

I have only ever installed engines from below, and this is how we planned to do it. I am fortunate to have a car hoist which makes the process a good deal easier.

3.8 JT5 01

With the engine on a trolley positioned under the car we lowered the body. It quickly became apparent that there was not much spare space; with the waterpump pulley a few mm clear of the picture frame the back of the gearbox was only about 10mm clear of the tunnel. Despite this we were able to get the engine in place on the engine mounts with a bit of judicious wiggling.

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It quickly became apparent however that there was not going to be enough room to get the slip yoke into the gearbox. Detaching the driveshaft from the differential didn't provide enough leeway either. Whether installing the engine from above using an engine crane and angling it down would have made it possible to install the yoke is an interesting question.

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After some discussion we decided to remove the IRS to give us enough room to manipulate the driveshaft into place. Even having done this it was still very difficult to get the splines to mesh and in the end we disconnected the slip yoke from the driveshaft and installed it by putting an arm up the tunnel much like a vet in calving season. Then the driveshaft was bolted back onto the yoke and the IRS reinstalled. Although it sounds complicated the removal and replacement of the IRS took about 20 minutes and was unavoidable.

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When we fitted the engine steady bar it was not vertical. After some measurment it seems that the engine is actually fitted in the correct place and that the mounting holes drilled in the bell housing are about 10mm too far back. Given the heavy duty gearbox mount that comes with the JT5 box this shouldn't pose a problem but it is disapointing.

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With the engine and gearbox installed it became apparent just how tight a fit the JT5 is. In many areas the clearance from the bodywork is only a couple of mm. "Some peening of the tunnel may be required" says the manual...

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The supplied cables for the reversing light switch are jammed up hard against the tunnel. There is very little room to access the gearbox filler plug; around 25mm clearance will make removing the plug and filling the box tricky.

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I am concerned at the lack of clearance particualrly around the bulkhead corners and the sides of the top plate. It will be quite hard to relieve these areas without changes that will make fitting the tunnel cover difficult. Depending on the amount of movement allowed by the gearbox mount it may be necessary to pack these tight gaps with some sort of rubber cushioning to stop rattles.

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In summary then the JT5 box will go in but not without removing the IRS if you want to put it in from below. It might be possible to get it in from above by tilting the gearbox down and manipulating it back on the slip yoke but this would be hard with a gearbox filled with oil as it will spill out of the unsealed hole around the output shaft.

In comparison we installed a Driven Man box in a 3.8 coupe 2 weeks ago. This has the same fixed yoke as the standard box and while it is also a tight fit it was a much easier installation.

Engine delivery

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Don't worry about those dirty old cam covers; the newly polished ones are just waiting until the engine is safely installed.

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There's always something else to buy...

3.8 engine lifter

Shimming the tappets

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Setting the valve clearances on the XK head is a time consuming process that requires patience. I have finished mine. It took me about 4 hours, never having done this before. Each side had to be pulled down about 4 times. I'm pretty satisfied though and the inlets are all 4 or 5 thou, and the exhausts 6 or 7. Once the Cometic head gasket arrives the head can go on, and it's done!

Rather than taking photographs of this process, instead have a look at what you get for $50 for an XK head. This is off a 420, and seems to have been stored in a dam.

4.2 rusty head1

Engine building 3: timing

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Time for the timing chains.

Everything has been beadblasted.

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Locktabs.

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Gaskets for the new chain cover.

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Teflon front seal.

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Cover on.

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Sump on.

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Damper on.

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Fuel sender in.

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Engine building 2: pistons

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Machined, balanced rods.

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New standard pistons. Rings have been checked in the bores by the machine shop.

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Assembly lube, slide the gudgeon pin in with the piston forward and the rod numbers on the exhaust side. Put the circlips smooth (not sharp cut) side IN. Check for positive seating by rotating clips with the circlip pliers. Leave the circlips pointing down.

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Lay out assembled rods in order.

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Insert bearings.

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All in.

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Set the engine at #1 TDC. Set the dizzy drive at 10 to 4 with the big D up. Tap the crank dizzy drive in until it just contacts the brass cog. Rotate the brass cog back 3 teeth (same as the width of the crank drive) and then slowly tap the crank drive home. This will put the dizzy drive properly back to 10 to 4 with the big D up at TDC. EASY!!

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Engine building 1

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With this car I really wanted to be involved in all aspects of the rebuild, and Chris the engine builder has kindly agreed to supervise me building the engine. Today we got a lot done in 5 hours.

Tappet guide hold downs.

3.8 Engine build13