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Tech QuestionsAugust 2003 Tech Q & A

Answers by Technical Editor Rex Chalmers

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August Topics:

Gas Tank Cleaning | Spider Engine Replacement | 164 Motor Mounts and Idle Controller
Missing with Webers | Poly Bushings | Skittish 164 | Bucking on Takeoff
Starter Problems when Hot | Duetto Shocks and Handling

Gas Tank Cleaning : question by Tom Parish | 1982 Spider

The secondary fuel pump in my trunk is getting clogged with "junk" and siezing. I'm tired of replacing it and worried that I will only destroy the main fuel pump. What is the best way to clean out the tank? Can I clean it while it is in place or does it have to be removed? What should I use to clean it out with? Are there any tank cleaning solutions?
Answer : The only way to clean out a tank as contaminated as yours appears to be is to remove it from your Alfa’s chassis and have it cleaned out. You can try to do it yourself, but I would recommend that you take it to a professional. Most radiator shops will boil out fuel tanks. You can try flushing it out in place, but these efforts are usually a waste of time. It’s not very expensive to have it done by a pro, especially when you start adding up the cost of fuel pumps and filters!

Spider Engine Replacement : question by Jeroen | 1993 Spider

I've just blown my engine at the Nurburgring, Germany, this weekend. I am not planning to rebuild my engine, instead i want to slot a bigger and more powerful engine in the engine bay. What's the cheapest and easiest way to fit a stronger engine? Which engine should I fit?
Answer : There is no cheap and easy way that I am aware of to do what you propose. However, several intrepid Alfisti have undertaken such projects with tremendous results.

Off the top of my head, I can think of several options for you:

First, for the true Alfisti, install a 2.5 or 3.0 liter Alfa V-6. There are several shops in the States who have done this conversion, including Hans Milo at Italian Motor Works and Nick Muto at Alfa Tech Center. I am sure there are German tuners who have performed this conversion as well.

A TwinSpark engine from a late Alfa Milano/75 will also yield power gains over your current powerplant. See Kelly McCrystle's excellent tutorial for more information on this conversion.

Of course, there is always forced induction. Jim Steck of AutoComponenti has been able to extract close to 400 hp from a classic Alfa twincam four using turbocharging and a modern engine management system.

The other option, which is much less elegant, it to install a Mazda rotary or other non-Alfa engine.

Hans Milo's 1973 GTV with V6 engine

164 Motor Mounts and Idle Controller : question by Robert B | 1992 164

Are motor mounts considered as consumeable items on a 164? I came across several messages in various Alfa forums which mentioned this. However I have not heard of this being a problem with other cars? Also can the idle control valve be cleaned or does it have to be replaced?

Answer : The motor mounts on your 164 are designed to do some very heavy lifting as well as performing the function of isolating noise and vibration from the passenger compartment. I don’t believe that given the silky smooth feel of the 164 you can fault the lifespan of the motor or transmission mounts. The most common situation that can significantly shorten the life of the mounts is, first and foremost, oil leaks. Any rubber mount or bushing that gets a diet of engine or transmission lubricant will have it’s useful life severely compromised.

Failures of the idle air control valve are fairly rare. I have successfully cleaned out a few that were sticking. I use brake cleaner and compressed air to clean gummed up components in the rotating box and manifold. If after cleaning the the manifold still fails to open properly there is a problem with the “monowind rotating regulator” . If the manifold opens but fails to close there is a failure of the “reaction spring”. In either case, the “idle adjustment actuator” will need to be replaced.

Missing with Webers : question by Eric Tannahauser | 1974 GTV

I have installed a pair of Weber carburetors on my 69 alfa with a 1750 engine. It runs pretty well except when the RPMs reach 5000. After 5000 RPMs it starts to miss more in the top gears. Should somthing about the timing be changed due to the addition of carbs or is this problem unrelated?
Answer : Generally, a timing problem will not cause a miss even when the timing is off by a mile. I am assuming that the engine was running without a miss before you switched over to the Weber carbs. Chances are that there is a problem with the Webers themselves, fuel pressure, or fuel delivery volume. First check the jetting, valving, venturi sizes, and float levels of your Webers. They should be set to stock 1750 specifications. If these are correct, check to see that the fuel pressure is around 2 psi. If the pressure is OK, check to see that you are getting proper volume of fuel. A system with a clogged fuel filter or some other in-line obstruction may show good fuel pressure, but would be sadly lacking in fuel delivery volume.

If the Webers check out OK, I would do compression and leak down test to rule out any mechanical problem with the engine. If those test results are acceptable, I would have to take a close look at all the components of the ignition system.

Polyurethane Bushings : question by Grant Hendricks | 1987 Milano Gold

I have owned my Milano since new and have covered 80K miles with it. Lately the bushings seemed to have softened up a bit and I was wondering if you have had any experience with Poly bushings. I'm worried that the plastic bushings will be to jittery for comfortable street use. I do not intend to drive on track, but am an enthusiatic driver all the same. Any info would be appreciated.

Answer : I totally concur with your feelings about poly bushings. They are generally harsh, noisy, and loosen up quicker than stock bushings when used for street driving. The best way to improve handling for spirited street driving is to make certain that all the bushings, ball joints, steering box, idler box and tye rod ends are in top condition. Then install a set of high performance street springs, sway bars and shocks. Now treat your Alfa to a good alignment. Have the alignment shop do a 4-wheel alignment. Even though there are no adjustments for the rear on the Milano, a 4-wheel alignment will help pick up any problems with the rear geometry. If you know someone with a set of scales, borrow them. They are a very helpful tool for setting ride height.

For competition use I prefer the use of spherical bearings over polyurethane: they are more expensive to purchase and install, but they last much longer and are better at maintaining alignment as they do not give or distort.

[Editor's Note: Several suppliers report their "soft formula" poly bushings do not have many of the drawbacks mentioned by Rex. Check out Centerline, International Auto Parts,, and Performatek for more info on these bushings.]

Skittish 164 : question by Ted Chan | 1992 164

A few weeks ago I felt that my car was a little "skiddish" when steering left at higher speeds. This is not noticeable below about 40mph but above that the car feels as if it was off center at the middle of the turn, almost as if the backend is still pointing straight. No problems turning right at all speeds. I had new shocks and springs with lower strut bearings installed 3 months ago. Could this be caused by bad ball joints, lower control arms or deteriorated bushings? Is this a common problem on 164's?
Answer : First thing to do is to check that all the nuts and bolts that hold the suspension to the sub-frames, and those that hold the sub-frames to the chassis are tight, and that the uprights are secure. I would pay special attention to the fastners that were removed to do the suspension work you just had completed. If all checks out OK, check all the tye rod ends, steering rack mounts and end bushings, lower ball joints, lower arm bushings, and all the rear suspension bushings.

Generally 164 bushings and joints have a service life somewhere between 70 and 100 thousand miles. The most common cause for 164 handling problems that I have come across is caused by bent rear control arms. There are two of these links in each side of the rear suspension. One is used to adjust rear toe and the other is of fixed length. They are fastened at the center of the rear sub-frame and attach on the front and back at the bottom of the rear upright. These links are not very strong and are often bent by tow truck drivers and others looking for some way to tie down the chassis at the rear. I had a customer here in Wisconsin who had his bent by a suicidal raccoon. I have also seen them bent where there is no sign of impact or other outside force. In any case, when these bend they adversely affect toe-in and camber.

If all seems in order, take your Alfa to a good alignment shop and have a 4-wheel alignment performed. I would explain your concerns and make sure to get before and after readings from the shop.

Bucking on Takeoff: question by Michael J. Aloi | 1984 Spider

I recently purchased this auto at an auction. It had a minor front end hit, no damage to radiator or beyond. It has a drivability problem mostly in 1st gear upon letting the clutch out at take-off. This problem causes the car to buck and jerk around 2000 rpm. If I rev the engine to 3000 rpm, and let out the clutch at take-off it lessons the bucking and in higher gears it is not as noticeable at all. I replaced the flex joint at the rear of the transmission and the drive shaft support, both were in bad shape and I thought this was my problem, never before working on an Alfa. Since the problem persisted, much to the dismay of my wife, who has absolutely fallen in love with this cute little red convertible, I must now rush to their rescue.

I was thinking it is not the clutch because when I place the parking brake on and let off the clutch in 1st gear it does seem like a smooth transfer of power and normal slipping with no vibrations or jolting. I feel my problem is most likely the distributor advance or the TPS sensor, or possibly the Mass Air sensor. I sure could use a more professional opinion though.

Answer : The most common cause of the symptom you are describing is a faulty air flow meter (AFM). Your Alfa doesn’t have a mass air flow sensor. I have replaced many air flow meters, but can count on one hand the number of throttle position switches that needed replacement. There are, of course, any number of other possible causes for your symptom including but not limited to vacuum leak, faulty ignition, cap, rotor, coil or wires, bad wt sensor, faulty processor, fuel pressure regulator, fuel pump, fuel filter, air leak between AFM and intake manifold, or a wiring fault, but I would start with the air flow meter. Most good Alfa technicians will have a good used unit handy that they can plug in to aid in a quick accurate diagnosis.

Starter Problems when Hot : question by Michael | 1974 Spider

My 74 Spider has been having a very disturbing problem over the last few months. My starter motor will not engage when the engine is hot.

On a cold start everything is fine, but after running for a few minutes the starter will not work again until the engine cools. I do get a click from the solenoid, and I hear the fuel pump turn on, but no crank. I have already redone the starter with no success.

The most bothersome about this problem, is that it is sporadic. It only occurs some of the time.

Answer : Chances are that the starter solenoid is faulty. I suspect that it was not replaced when the starter was rebuilt. If the starter was properly rebuilt and the solenoid had been replaced, the starter should not be the problem. Check for battery voltage going into the ignition switch, check for the same voltage at the impulse in to the solenoid when the starter is engaged and at the main battery B+ terminal. If they are significantly different, look for a problem with the ignition switch or the wiring to the solenoid. Check that the engine ground strap is making good contact. It is also a good idea to install a starter relay so the points in the ignition switch won’t have to deal with the amperage loads of the starter solenoid.

Duetto Shocks and Handling : question by Frank | 1969 Duetto 1600

I have just been given a set of used yellow Koni sports shocks and they appear to be working fine. I have since fitted them to my Duetto to replace the worn out bilstein that went rock hard. This replacement was done just last week when I had all the bushes front and rear changed with new ball joints all round. Only part not changed is the trunion to body bush.

I know this is a subjective question but how should I set the yellow Konis for comfort with a bit of performance to it? Currently I am playing with the settings where the front are stiffer than the back. The back is 3/8 turn from soft and front is 7/8 from soft. (I am aware that there will be some wear on the shocks and so I am compensating abit for them). Since the bushes job was done, I have noticed a lot more soft knocking (kling-klong) noise coming from somewhere near the rear axle as if something is loose - this is when I say maintain a constant speed. Worn shocks? Or that the shocks are not tightened properly?? How tight should I tighten the shocks to the anchoring points anyway?

I do not race but like a bit more control but not at the expense of ride comfort. In any case, which would you recommend, the yellow Koni shocks or the red shocks? Or the originals or some other shocks? Also how should I set them up when new?

As an aside, how do I know if I have worn U-joints? Do they make any kind of sound? When I accelerate away from the lower gears and when I press the clutch down, there would be some kling-klong noises coming from what sounds like under the transmission tunnel... could the loose u-joints be the source of the soft kling-klong noises?

Answer : Frank, Frank, Frank, get a grip. If you want more control, go soft. A shock absorber is not a spring, it is a shock absorber, it’s job is to keep the tyre in contact with the tarmac. Hence, the stiffer your make the rear shock, the more likely you are to create oversteer on an uneven or bumpy surface, even snap oversteer over some bumps. The stiffer you make the front shocks, the more likely you are to create understeer on the same surface. Most racetracks are a heck of a lot smoother than most public roads and highways. Because of this, and a number of other factors, most racecars are set very stiff. If you want to improve the street handling of your Duetto, I would install a set of street performance springs and sway bars. I would then purchase a set of non-competition shocks and spend some time enjoying driving your Alfa rather than adjusting the shocks.

As to your question on the proper tightening of the shocks to their anchoring points: The shocks should be tightened to the point where the bushing visibly squeezes out from under the captive washers.

As to the cause of your “kling-klong” noises, check all the usual suspects in the drive shaft. Yes, the U-joints can cause a noise from the transmission tunnel. So can a loose or failed front flex disc or a worn center support or bearing or loose drive shaft bolts themselves.

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