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ALFAcentro T E C H Q & A
Tech QuestionsDecember 2002 Tech Q & A

Answers by Technical Editor Rex Chalmers

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October Topics:

ERide Height Settings | Timing Chain Longevity | 164 Engine Cooling | Crankshaft Repair or Replacement | 164 LCD Display Repair | Timing Chain Tensioners | O2 Sensors and Emissions

Ride Height Settings : question by Terry Rushbrook | 1979 Spider

I replaced the front and rear springs with new "progressive" springs, but now have only 1 1/2" clearance between the road and the oil pan. The measurement at the rocker behind the front wheel is 2 1/8" lower than the measurement at the rocker in front of the rear wheels. The rake seems a bit radical, don't you think? I have been told to shim them to the proper height, but I don't know what that proper height is, how many shims to use, nor do I know how much it should be raked. Can you help, please?
Answer : You are correct, the oil pan is a tad too close to the tarmac. I have setup racing Alfas to as little as 2.5 inches, but even if you were using springs and shocks suitable for racing, I would not recommend that measurement for street use. Four inches is as low as most drivers like to go for street driving.

I like to set the front about 2 in. lower than the rear for a starting point. On a level surface, at the jacking points measure the bottom of the rocker panel to the ground at 7” front and 9” rear. I would not go much lower. This ride height may be too low for some vehicles depending on tire size, type of shock absorber and spring installed. As to what size shim to use; it’s pretty much a trial and error process. This is because different springs of varying spring rates will compress to different degrees. It is also true of used springs, as springs tend to lose some of their tension over time.

Timing Chain Longevity : question by Francis | 1967 Duetto

When should I change the upper and lower chains in the engine? How long do they last? My chains are loose now (which I can tighten?) and I am not sure if they had ever been changed before. There are those who say that the chains can break (which I have heard and seen for myself in 2 cars a 69 Subaru and a mid 80s Jap van) while some others says that the Alfa chains are very strong and never break. What is your view?

Must I remove the engine in order to change the chains?

Answer : I have been working with Alfa Romeo engines for over thirty years and have never seen a timing chain, either upper or lower, break. The lower chain is not adjustable; it will stretch, and can adversely affect ignition and cam timing. Generally, lower timing chains will show signs of wear by 60-70 K miles of use, some less and some more. In order to change the lower chain the cylinder head, oil pan and front cover must be removed. This can be done in the vehicle, however, a cleaner and better job can be done by pulling the engine and performing the repair on the bench.

The upper chain has a manually adjustable tensioner. The manual says to warm up the engine and, with the engine idling (NEVER rev the engine or blip the throttle, severe valve damage will occur), loosen the tensioner for a few seconds and then re-tighten. This procedure will *occasionally* accomplish the desired adjustment. If the upper chain rattle is still audible, it may be necessary to manually adjust the chain. I find that the best way to adjust upper chain tension is to remove the cam cover, bring the engine to TDC, loosen the tensioner bolt and adjust the tensioner with a large screwdriver or other suitable prying tool. The factory does not specify the correct deflection of the chain. Be very careful not to tension the chain too tight, as a seized front exhaust cam journal will be the result. This is not a happy occurrence and should be avoided at all cost.

164 Engine Cooling : question by Carman | 1991 164L

After 10 years I have never noticed my fan running - the car operates normally - maybe at the hot end of what I would expect.

Shouldn't a hot engine be running the cooling fan after I switch off? If so other than a fuse what should I be looking for?

Answer : If you were talking about a VW, expecting the fan to run after engine shut down would be correct. But, we are discussing the intricacies of the Alfa Romeo motorcar. In the world of Alfa, voltage to the cooling fan is terminated when the vehicle is shut off. As to your vehicle running at the high end of acceptable coolant temperature, this is normal for a 164.

Editor's Note: Many 164s suffer from a failure of the low speed fan thermistor. When this unit fails the cooling fan will not come on until the high speed thermistor kicks in at around 205 degrees F (versus around 190 degree F low speed fan turn on with a working low speed thermistor) and can cause hot running around town and in traffic.

Crankshaft Repair or Replacement : question by Frank LaSala | ’58 750B

I have a crankshaft that is at .02 and the rod journals are scored. I want to vintage race this engine. Do I need to find another crank? and if so where?
Answer : You have several options to consider. First, have the crank cut to .030”, have it heat treated, polished, the oil holes champhered, and the journal plugs drilled out and tapped to facilitate proper cleaning of the crank. Cutting the crank to .030” doesn’t bother me at all. There are engineers out there who will tell you that it is actually good to use an undersize crank in a race motor, as it will actually cut down on crank/bearing speed. Second, you can always try to find a replacement crankshaft. First place a want ad on! Next, contact your local Alfisti, check out Ebay, communicate your needs on the several Alfa newsgroup lists, and in general ask around in the Alfa community.

164 LS and Q HVAC LCD Panel Repair : question by John Dolgetta | ’94 164LS

My LCD display for fan speed, time, climate control has been fading away slowly… It appears that soon it will no longer display any information. Is there anything I can do to repair this or stop it from happening? Are there extensive costs involved?
Answer : Unfortunately, what you are describing is the manner in which any display screen of this type fails, painfully slowly. Especially in this case, as my Webmaster informs me that this unit lists for $1300.00, yes, thirteen hundred, that’s one thousand three hundred US dollars. You can first check the voltage supply and the ground, but I believe you are going to be surfing the web and any other source you can think of for a used unit very soon.

Editor's Note: Some intrepid Alfisti have reported success with repairing the connection ribbon. For details of the process, see the this link to the Alfa Romeo 164 Homepage by Colin Verrilli

Timing Chain Tensioner: question by Pete Accini | ’67 GTV

Hi, my car had its engine rebuilt by the previous owner about 4000 miles ago but it sounds a bit rattly to me! I'm pretty sure that the noise is from the top timing chain. When I bought the car I had a garage give the engine a quick once-over and they suggested that the chain tensioner is not properly working or at least the adjuster isn't. Does this sound likely and if so what kind of a job is it to replace the adjuster.
Answer : First of all, you need to understand that the chain tensioner in your engine is a manual, not automatic, tensioner. In general, it is a fairly simple operation to replace the chain tensioner of your vehicle. However, it is a fairly rare occurrence for the tensioner of a 105 Alfa engine to fail. Chances are that it just needs adjusting. If proper adjusting of the chain doesn’t quiet things down, it’s probably not the upper chain that is making the noise.

O2 Sensors and Emissions : question by Roy Moreno | ’85 Spider Graduate

My car failed WI emissions after passing 2 years ago. Performance has not changed with car over the past 2 years. CO at idle was elevated, other values passed at idle and 2500rpm. In addition to new spark plugs, new air filter, new oil and cleaning up contacts of distributor, I am contemplating changing the 02 sensor. I have heard that the 3-wire type is better than the 1-wire type? Is this true for the 1985 model? There is a modification that reuses part of the 1-wire to adapt the 3-wire. Would this be advisable? Drawbacks/durability issues?
Answer : The only advantages to the three wire O2 sensor that I am aware of is that it warms up faster, thus providing better drivability during the warm up cycle and it provides a more consistent and accurate signal to the processor at idle. The three-wire sensor has a power and ground circuit for the heater and the third wire sends back the sensor reading to the processor. There are also four wire sensors. These have separate power and ground circuits for the heater and for the sensor. In a one or three wire sensor, the sensor circuit is grounded only by the exhaust system itself. Whenever you are taking an emissions test, it is very important to get the converter hot enough to function at its best efficiency and not allow it to cool down before the test. I recommend getting the engine up to full operating temperature on the highway, driving the car spiritedly, and, very important, do not turn vehicle off as it will cause the cat to cool down and become less efficient. A new O2 sensor may cure your emission woes, however it appears as though your Alfa has the classic symptoms of an inefficient catalytic converter. Your car is the age when we see the performance of many converters fall off significantly.

Editor's Note: Catalytic converter technology has come a long way since 1985. In addition to improving emissions, a new converter may offer increased flow leading to a boost in perfomance.

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