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| Original tall piston and short rod (top); short piston and tall rod below. The new pistons and rods are much lighter. DeWayne Samuels. |
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| Machining the relief in the piston valve pocket. DeWayne Samuels. |
That depends . . .
I thought rebuilding The Alfatross' original, matching-numbers engine would be the easiest, fastest, and least costly part of the overall restoration. At first glance, it's pretty old school: 4 cylinders, 2 carbs, a cast-iron block and 1950s technology--How hard can it be?The fact that the previous engine re-builder couldn't do the job in eight years should have made me rethink the true magnitude of the task. Working with DeWayne Samuels and Roger Lorton over the last three years I have come to appreciate at least some of the intricacies of rebuilding the Alfa Romeo 1900 SS engine.
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| Machining the valve relief bosses. DeWayne Samuels. |
Yes, the engine is simple in terms of number of moving parts, but some of those parts were damaged beyond repair and had to be replaced. This opened the door to modification options.
Keeping Up Appearances
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| The valve spring seat areas were machined to take a chrome moly hardened spring seat DeWayne Samuels. |
Externally, the engine will look exactly the way it did originally. This is a claim that few of The Alfatross' brethren can make, particularly the road-worthy ones. Many have traded their original Solex 40 P II carbs for Webers and in the process jettisoned their emblematic but heavy, cumbersome air filter housings. This is understandable because Webers are the performance carburetor of choice, but we're sticking with the original Solexes.
Internally, though, there will be significant differences. Throughout the restoration of The Alfatross it was always paramount to maintain originality. With the engine, that meant cleaning and reusing old parts whenever possible rather than replacing them. But those original parts are now 60 years old and some of them have been rode hard and put away wet.
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| Correction of a design flaw: installation of "stepped seat" washers provides a hard surface for the studs nuts and washers to bear on. DeWayne Samuels. |
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| "New and improved" valve guides with relocated spring seat bosses and areas for valve seals (which the originals never had. DeWayne Samuels. |
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| Preparing the crankshaft for installation in the block. The discoloration is a result of the nitriding process which hardens and strengthens the steel. DeWayne Samuels. |
Engines are designed to be maintained and repaired, so replacement of parts that wear out relatively quickly is not only necessary, but perfectly natural. Problem is, with the exception of certain parts which continued to be used in later models, finding replacement parts for an engine that has been out of production for half a century can be challenging. From the beginning it was apparent that if we were going to restore The Alfatross' sprightliness the engine's internals would have to be modified. Is this a departure from originality? Yes, but a necessary and rational one.
As I mentioned in a previous post, The Alfatross' cams, pistons, and exhaust valves needed replacement. DeWayne spent some time researching NOS parts but very quickly concluded that if we had cams and pistons made to order rather than "stock" we could improve power and reliability. But as long as we were having them made, we could have them made better--more in line with modern engineering principles. We could go with shorter pistons and longer connecting rods instead of the stock tall pistons and short connecting rods--and up the compression ratio at the same time.
Improving Performance
Engine engineering has come a long way over the last 60 years. We can do things now to make an engine last longer and run better and more efficiently. Some modifications are as simple as hardening and polishing contact surfaces, or installing stepped washers to prevent the steel washers and nuts that torque down the cylinder head from gouging into the much softer aluminum.Others are small refinements to reduce friction and wear such as improving valve guide configuration. Still others get into some serious re-engineering of the engine's internals. Changes made to one element, like the connecting rod length, necessitate making changes to other elements so that everything works in concert.
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| The five main bearings saddled into the block in preparation for receiving the crank. DeWayne Samuels. |
A good example of this cascade effect is the way changing the length of the connecting rod changes piston velocity, which changes the fill/empty cycle rate of the combustion chamber, which in turn necessitates developing a new cam profile--all doable, we just have to get the entire package working in concert so the outcome is what we want in all aspects--not just parts stuck together.
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| The crank, fitted to the block. DeWayne Samuels. |
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| Flywheel end of the crank with the oil slinger in place DeWayne Samuels. |
