Rebuilding the delicate twin-cam: Part one

Alfa Romeo’s Twin-Cam, 8 valve engine is nothing short of legendary. It was produced for 40 years, from 1954 to 1994, first in the Giulietta and last in the S4 Spider.

It was built in four displacements, 1300, 1600, 1750, and 2000. It produced from a modest 62 BHP all the way up to a mad 240 BHP when it was in the hands of the mentalists at Autodelta, as a 2 litre Supercharged unit. It enjoyed great success in motorsport with a twin-ignition cylinder head in the GTA and 1300GTA Junior. It was even used in Formula 3 cars for a while.

However, in my car it does none of these things, as my one is absolutely ruined.

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My 1600 Twin-cam, in all it’s crappy glory.

The original 1600 engine out of my car had, at some point, been in the care of a moron. It had over heated and destroyed all the piston rings and blown the head gasket. This is most likely because it had the wrong thermostat, which had come loose and jammed shut in the top radiator hose. It also had a BMW fan, which is not as good as an Alfa fan. Obviously.

Originally the liners in these engines were simply sealed with a rubber O-ring, between the liner base and the block. But as they aged it became common practice to add a little high heat silicone as a “belt and bracers” solution. Very wise.

However, a previous owner decided to forgo the O-rings and high heat silicone and seal the liners with the sort of glue you would use to install a headlamp cover. Brilliant.

And this is the result…

IMG_1937

Oh dear…

Just awful, awful corrosion. Water had been in the oil for years by the time I pulled this engine apart. It might as well have been stored at the bottom of the sea, for all the damage it did.

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Cylinder head off.

There was plenty of corrosion in the water jacket,  which occurs when plain water is run as a coolant, in place of a proper corrosion inhibiting solution. The crankshaft was also so rusty that I had to simply throw it away, along with the camshafts.

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A liner, showing black silicone around the base, no sign of an O-ring.

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Galvanic corrosion evident on the outside of the liner.

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Replacement liner (left) alongside original.

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Charred piston with damaged rings.

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Ruined pistons, sitting on the shelf.

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All apart. Let’s see what we can salvage…

Next? What can be done to get this engine swinging again?

 

 

 

2 Comments

  1. […] As I might have mentioned in my last post, many components of my twin-cam 1600 were damaged beyond salvation by the time it landed in my […]

  2. […] All was going brilliantly. Thought I’d drop the engine and gearbox in this weekend. So I hooked up a small pump to pump oil through the engine to get it ready for its first firing. Surely I was finally out of the woods. The engine filled up nicely. I watched as clean oil filled up around the cams (good psychology apparently) and was satisfied that everything was good to go. My last job was to replace the copper washers sealing off sender units and such. And as I undid the water jacket drain engine oil poured out from the thread. What’s engine oil doing in the water jacket? Something must be very wrong indeed. This must be Giulia’s terrible secret, the fault that wrecked the engine at the start. […]

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