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Tech QuestionsAugust 2001 Tech Q & A

Answer by Technical Editor Rex Chalmers

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August Topics:

TECH TIP : Cylinder Head O-Rings and Roll Pin Problems |
Lightened Flywheels | Bosch Injection Turbo Charging | Starter Heat Soak

TECH TIP : Cylinder Head O-Rings and Roll Pin Problems

Cut O-Rings with Split Roll Pins

Split Roll Pins actually cut the O-Rings on this motor
I had a customer bring in a 74 Spider with a nasty mixture of oil and water circulating though out the entire cooling system. The owner explained that he had the engine re-built some 15,000 miles ago and was quite concerned about the engine’s condition. When I told him that I expected failed cylinder head Orings, he was not impressed with my diagnosis. He told me that he had the tech who built the engine install viton Orings and Oring pins and that there must be some other cause for the oil contamination of the cooling system. I explained to him that the viton Orings are good but that the Oring pins he described could actually cause Oring failure and the inevitable cooling system oil contamination. I pulled the head, and sure enough, the specter of dreaded Oring failure had, indeed, occurred. Not only had the Orings gotten hard, from lack of proper oil change intervals, several of the Orings had actually been severed by the sharp edge of the head pins (see photo above). As you can see from the picture, two of the Orings were severed; others appeared to be in decent condition. All of the Orings were harder than they should have been. The owner admitted to me that he had been changing oil at 7,000 mi. intervals. The build up of hydrocarbons in the oil will cause the Oring to harden. Viton Orings are not as susceptible to hardening as the rubber ones that Alfa supplies, but they will also harden, especially when the oil is not changed at proper intervals. When the Oring hardens it does not expand and contract with engine temperature and makes it easy for oil to pass by the Oring and contaminate the cooling system. If you have occasion to replace your head gasket, be sure to use Viton Orings. As far as helping the Oring from collapsing goes, I prefer the Stainless Oring inserts or, if you feel you must use pins, roll pins that Alfa Ricambi, International Auto Parts, Centerline, Linea Rossa and other suppliers of Alfa parts can provide. Remember, the function of the roll pin or insert is to keep the Oring from collapsing and changing to a shape other than round, not to seal oil. Do not use the style of pins in the picture that are split on one side.

Lightened Flywheels : question by Joe Sloan | ’82 Spider Veloce

I need to replace the clutch on this street complete stock car with 63,000 miles. I considered going with a lightweight flywheel. I had heard somewhere that this was not a good idea for Spiders, especially street cars. Should I just go back with stock stuff. My goal is to eliminate as much rotating weight as possible.
Answer : If your goal is to eliminate as much rotating mass as possible, a lightweight clutch and flywheel is the way to go. I can’t think of any reason why this modification wouldn’t be good for a spider but would be for a GTV or Berlina. If you think about it, a Spider would probably benefit more because it has the best power to weight ratio of the three Alfas. That said, I wouldn’t recommend installing a lightweight flywheel on an Alfa with a stock motor simply because in order to make good use of the lighter reciprocating mass you need to use more rpm, which you, because of your stock motor, just don’t have available. The installation of the lighter components will allow the motor to rev more freely, but because of your stock motor you will run out of revs quickly. You will also loose revs at a faster rate, which is fine in a race car where the motor is generally spinning between 5500 and 8500 rpm at all times, but makes a street car harder to drive because of your loss of some of the flywheel affect that the rotational mass of the steel flywheel provides. That is the principle of physics that explains why heavier objects are harder to stop when set in motion than lighter objects. If you want a bit more power put in a set of Euro 2.0 cams. They will give you a nice horsepower and rpm boost. If your car has a rev-limiter, you will need to modify the processor. In general, I don’t like lightened flywheels on stock Alfas. I’ve used them to good affect on dual purpose cars that are used for time trial or vintage racing, and only get occasional street use and on all out race Alfas.

Turbo Charging with Bosch Injection : question by Noel | '87 Spider

I have a Bosch-injected Alfa and would like to turbo charge it, could the injection handle this with minor mods or would it be better to go to an aftermaket injection system. Has anyone ever turbo'd a Bosch system?

Answer : In my view, to have a satisfactory result, it is essential, when turbo charging any engine, to be able to tune both the ignition and fuel systems. If you don’t have the capability to tune these systems, you will most likely experience detonation, surging, flat spots, and a virtual plethora of drivability problems. So to answer your question, with out jumping through many expensive hoops, your Bosch system is mapped for the streetcar you have, and would not function well with a turbo without extensive modification and testing. I am sure someone has put a turbo on a Bosch system, I don’t know of any, maybe that person will read this and enlighten us.

Starter Heat Soak : question by Harrison Voigt | ’74 Spider

I have a "heat-soak" problem with the .7 amp starter, where starter will not function when engine is hot. What, in particular, is usually the problem with the starter in this case? Also, I have a few spare .7 amp starters but do not know whether or not these will be a correct match for the ring gear on my Alfa (number of teeth unknown). Is there any way to tell from the starter serial number what ring gear it will match?

Answer : The Achilles heel of any Bosch starter is the solenoid. The condition you describe can generally be cured by installing a known good solenoid. I have seen this condition caused by the ignition switch or a wiring concern as well. If your Alfa doesn’t have a starter relay, I would strongly recommend installing one. One way to check for low voltage to the solenoid is to jump from the battery to the solenoid. If the starter works, you can be fairly certain that it isn’t getting enough voltage from the ignition switch. The best way to diagnose this problem is with a voltmeter. With the starter hot and not engaging, install the voltmeter between the black impulse wire to the solenoid and the impulse in terminal on the solenoid. Next turn the ignition switch to the start position and look at the voltmeter. You should see pretty close to battery voltage (12+ volts). If you do, then you have a problem with the solenoid or starter’s motor. If you don’t see 12 volts, check the ignition switch voltage output and resistance of the impulse wire from the starter to the solenoid. I’ve seen many Alfas with high resistance in the ignition switch, this generally occurs in Alfas that don’t have starter relays. Without a relay, the switch takes the full electrical load when you start the car. With a relay, the relay takes the load and all the switch has to do is energize the relay.

The only sure fire way to know if your extra .7 starters will work with your ring gear is to count starter drive teeth. Pull your starter out; if it is a 2.0L engine the drive should have 9 teeth. 1750s have 8 teeth. If they aren’t the same number of teeth, you could swap the drive from your problem starter to one of the spares.

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