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Alfa Romeo - Tech Session with Scarborough Engine and Machine

Early last year I was deeply involved in an engine-rebuilding project so that I could upgrade my Spider Jr. to a 1750 engine. Of course, some of us - especially me – absolutely can’t leave well enough alone and need to upgrade and optimize things as we go along. This led me into porting, flow testing and balancing exercises as the project progressed. It was during this rebuilding project that I came in contact with Scarborough Engine and Machine through a mutual friend of the company’s owner, John Solecki. At the end of the exercise, John mentioned that he would be happy to put on a technical session for the Alfa Club if we could work it in to our events schedule.

About a dozen members gathered at SEM’s location on November 12 for this session. After introductions over coffee and donuts. we started a tour of the facility.

Even though I had been in this shop before as a customer, I had no idea the range of capabilities that SEM possesses until this tour. As background, SEM has been in business since 1978 and has done engine work for many different manufacturers, both for street and racing purposes. At this time, it is doing
machining and rebuilding work for a major manufacturer on a contract basis and machine work (not rebuilding) for a range of other customers. In order to meet the exacting specifications of the industry these days, SEM has made substantial investments in state of the art equipment for all aspects of engine and transmission machine work. A partial list includes milling machines for surfacing heads, blocks and flywheels, articulated milling machines for specialized block work, boring and honing machines, a single-point valve seat cutting machine, a balancing machine for rotating parts and a flow bench.

The good news for enthusiasts who want to do engine rebuilding them selves, or who might need to direct their rebuilder to a knowledgeable shop, is that SEM has enough capacity to welcome walk-in customers and deal with their individual requirements using the same equipment that is required for contract work.

Our tour of the shop lasted about three hours, and we were able to observe a number of these machines in action. The one that impressed me the most was the Serdi valve-seat cutting machine. The traditional approach to valve seat cutting is to use different cutters or stones for each valve seat angle. For those of us who want three-angle valve seats, it is tricky to get a nice even middle angle for good seating properties using traditional equipment. Because the Serdi is a single-point device, one contoured carbide cutting tool is used to machine all three angles at the same time. This guarantees that the middle or seating angle will be perfectly uniform. That, and the system that aligns the cutter to the valve seat ensures uniform valve to seat contact and therefore ideal sealing between the seat and the valve. A vacuum test is incorporated in this equipment to verify valve sealing while the head is still on the machine. The Serdi machine also minimizes shop time, because the actual seat cutting is all done at one time and takes only a few seconds per valve seat.

This is only one example of the sophisticated machinery we got to see in action.

The discussions that we had with John covered a wide range of topics regarding machine work and engine building. One topic we spent a fair amount of time on was cylinder bore and piston ring finishes, and what is accomplished during break-in.

We had a very informative discussion on cylinder bore finishes, their compatibility with piston rings and how thinking has changed over the years with regard to control of the surface finish of both rings and cylinders. This extended into a chalk talk regarding what is accomplished at break-in. This discussion is very relevant to those of us working on older Alfa engines. The OE cylinder liners that are still sold for our engines are made with a relatively coarse finish by modern standards. My experience was that the ring supplier I used (Total Seal) recommended a much finer finish, which was achieved by diamond honing at SEM.

We talked about this and many other topics at the shop and over lunch at the Victoria and Albert pub after the tech session. I think everyone who attended found the session useful and informative. At least a few of us will be putting the learning to good use over the winter.

We were all grateful that John provided us with this eye-opening and informative experience.