Most of the following technical advice on Maseratis was donated by ace mechanic, Wil DeGroot of Exoticars USA in Frenchtown, NJ (908) 996-4889. See the link to his website below.
Contents (General Tips):
Fuel System Tips
Rust Prevention
Tech Tips For Maserati Knock-off Wheels
Tech Tips For Maserati Bolt-on Wheels
Storing your Maserati in Winter
Is Your GT Maserati Healthy?
Tuning Your Weber Carburetors
Contents (Specific Tips):
Specifications for Ignition Timing, Distributor Curves, and Carburetor Settings for 4.9 Litre Ghibli and Bora Engines
If you drive one of the older GT cars and enjoy doing some of the maintenance yourself, you may have shied away from the fuel system because of its complexity. It's true that setting up the fuel injection or multiple Weber carburetors is better left to someone with experience. Checking to make sure that the engine is getting an ample supply of clean, cool air by inspecting the air filter housing, filter element and ducting for proper sealing and cleanliness is important and well within the capabilities of most owners. Keeping the fuel supply system up to snuff is also important and within the capabilities of most owners.
Make sure that the fuel cap fits snugly and that the rubber gasket isn't cracked. If, after driving the car, a hissing sound can be heard while loosening the fuel cap, you have a venting problem. Cars from the early seventies and before should have vented caps which allow air in to the fuel tank as the fuel level drops. Later cars have special venting systems which serve the same purpose but also capture fumes coming back out of the tank. In either event, air must be allowed in or fuel will not be allowed out.
Be sure the fuel tank is securely mounted and properly isolated with some sort of cushioning material between tank(s) and whatever is holding the tank in place to prevent holes from wearing through. Fuel tanks should be grounded to the car body or chassis to prevent electric arcing and to help the fuel gauge do its job.
Check tank and all hoses and pipes for wet spots or cracks. Check hoses for swelling or loss of flexibility. Be sure all fuel hoses and lines are kept away from sharp metal edges and away from the exhaust system. Check all hose clamps and fittings for tightness. Replace corroded clamps and any suspect hose or metal fuel lines.
A note about safety: if you must replace a fuel hose or pipe, be sure to clamp off the system between the tank and the repair, using the proper tool. If clamping is not possible and the repair is not above the fuel level in the tank, the tank will have to be drained. Before starting, be sure you have enough empty gas cans, a good size funnel, and a clean drain pan. If you can, pump as much fuel out as possible before removing the drain plug. Keep all sources of heat, spark or flame, far away. That includes smokers and droplights! Have a fire extinguisher handy and preferably, do it outside. You won't have to worry about fumes being ignited by the furnace, water heater, etc. Draining the tanks is also a good way to purge debris and water. If debris such as rusty scale is a problem, this may be a good time to have the tank professionally cleaned and epoxy coated inside and out. If that is not an attractive option, a large in-line fuel filter such as a N.A.P.A. #3097 installed between the fuel tank and the fuel pump will sometimes to the trick. This unit is the size of a medium oil filter and will absorb a lot of scale before clogging. If the gas you removed is old and full of debris, put a paper paint filter in a funnel and mix the dirty old gas with the other fuel in your daily driver a few gallons at a time.
A few other fuel tank notes: When storing your car, keep the fuel tank full. It prevents condensation and collection of water. Over the winter add a fuel stabilizer.
Most older Maseratis use Bendix electric fuel pumps which come close to looking like a beer can. These pumps are reliable and have a cleanable pre-filter element which can be accessed by unscrewing the bottom. (The same cautions mentioned above apply to servicing the fuel pump.) Exact replacements are still available from your local NAPA store. Ask for part #6101016. Make sure it has a round red label on top for the correct pressure range. Before replacing your old pump, check to see if it's getting a supply of fuel, that the pre-filter is clean, that it is receiving battery voltage, and that all connections including the ground wire on the pump are clean and secure. The pump should be rubber mounted, (NAPA part #35-144).
After fuel leaves the pump it is pressurized and flows to the engine via the "filter valve" unit, which on most Maseratis consists of an old fashioned glass sediment bowl with a paper cartridge fuel filter inside, mounted under a diaphragm type fuel pressure regulator. On most cars it sits next to the engine, high up on an inner fender. The Weber carburetors like the fuel pressure to be 2 to 2.5 lbs., no more, no less. Checking fuel pressure with a gauge connected to the out port on the "filter valve" is a good idea. Very often the "filter valve," even after cleaning out the glass bowl and replacing the filter element, will no longer regulate the pressure. New, non original units are available but usually the easiest solution is to splice an adjustable fuel pressure regulator (NAPA #730-2367) into the fuel line, somewhere not too noticeable, between the pump and the "filter valve." You also want to have enough fuel flow to the carburetors, about an ounce per second is good. If you remove the supply hose at the carburetors you should be able to fill a 20 oz. pineapple can in about 20 seconds or so. Just dump the fuel back in the tank.
This article really ends at the carburetors but you should make sure all the brass bolts holding the banjo fittings are snug and that none of the fiber washers are broken, distorted, or leaking. Check the nuts holding the carburetors to the manifolds and the screws securing the covers. Never over tighten anything on a carburetor, and use the correct size and type screw driver or wrench.
One last note about the carburetors. The Ghibli, Indy, Bora, Khamsin, Merak, Quattroporte, and Bi-turbo all used the DCNF style of Weber carburetors. While it's a fine fuel metering device, it has an Achilles heel-it uses an externally mounted accelerator pump with a diaphragm in it which, when it gets old, can rupture and spew fuel all over your hot engine. Consider it good insurance to change the accelerator pump diaphragm on each carburetor every few years. If you are unsure how old they are, change them.
Each DCNF carburetor has a little square cover with a screw in each rounded corner. Emanating from the center of this cover is a lever that is activated by a cam on the throttle shaft. With the engine cold, remove the four screws holding the cover(s) and replace the diaphragm(s) making sure not to tear or wrinkle them and that you don't put them in backwards.
Following these recommendations should make your Maserati much safer, more reliable and more fun.With the possible exception of people who lease cars, rust is every car enthusiast's worst nightmare. Having invested time and money in a Maserati does not make rust any less nightmarish to say the least. Rust is inevitable. Nature eventually reclaims everything. However rust can be postponed for a long time with a little TLC.
The thing to remember about rust on a car is that serious rust starts on the inside. Don't worry too much about paint chips. Chips don't look good, but the surface rust that develops there usually never amounts to much because it's usually dry. The nasty stuff grows in the bottoms of your doors, in the rocker panels, wheel wells, under windshield gaskets, etc. By the time most owners see that kind of rust, serious, expensive damage has already been done. That kind of rust is like the proverbial iceberg. There is much more below the surface.
When washing your Maserati, equal attention should be paid to the underside and the exterior. Make sure there are no piles of dust and road debris inside the wheel wells that can get wet and stay wet for weeks. Make sure that all splash aprons are in place but occasionally remove them to inspect and clean behind. Remove interior door panels and clean out debris that tends to collect in door bottoms. Make sure all drain holes are free and that everything is dry, particularly the crevice formed by the outer door skin and the door frame coming together. It's a good idea to blow this crevice (called the 'pinchweld') out with compressed air and squirt some penetrating oil down there and up the sides to displace any water deep inside. Follow that a few days later with an oil pump can filled with motor oil. Some people like to use wax-oil or similar products which are thicker than motor oil and stick to vertical surfaces. The problem with those products is that if they are not used properly they plug up drain holes and make the situation worse by trapping water and they just can't penetrate into trouble spots like pinchwelds.
A hand pumped garden sprayer can be filled with oil and the spray wand poked inside areas otherwise inaccessible. You may have to drill some holes under sill plates and other hidden areas to gain access to rust prone regions of your car. Don't forget to clean and spray around the gas tank and in the bottoms of the rear fenders-any place where dirt and water can hide and wreak havoc.
Do the job on a large, heavy duty plastic sheet and let your car sit and finish dripping for a few days with the doors open. Most of the oil that falls to the floor can then be squeegeed and reclaimed.
A word about undercoating: this product is often mistaken for rust proofing material. Actually, it's used more to deaden road noise and can actually promote rust when it dries and cracks to form water trapping pockets. It's a good practice to inspect every inch of the bottom and remove any cracked or loose undercoating with a heat gun and a scraper. A propane torch will work also. Make sure you have good ventilation and safety equipment such as a hat, goggles, gloves, and long sleeves.
Spraying oil on old undercoating that is not loose will help rejuvenate it, if you don't want to redo all the undercoating. Don't spray the exhaust system or rubber parts.
Check under the carpeting and see that it's dry under there. Water leaking in from rain or car washing is not uncommon and wet carpets can cause serious floor rot.
If rust is starting to grow along the windshield or rear window gasket, the best cure is to cut the gasket with a razor knife and carefully take the windshield out. You can now sand, prime, and paint the offending area and have the windshield installed with a new gasket. Left alone, this kind of rust will eventually turn into a hole.TECH TIPS FOR MASERATI KNOCK-OFF WHEELS
The splines (teeth) and threads on the hubs and inside the wheel centers must be kept clean and well lubricated with grease or the wheels may not come off the next time you need them to. The lubrication also aids in correctly tightening the wheels to the hubs. More on that later.
Some owners have objected to greasing the splines on Borrani wire wheels due to unsightly black grease on the spokes from the lubrication slinging through the spoke holes with centrifugal force as the wheels spin. The cure for that is to clean and dry the inside of the wheel centers very thoroughly. Then apply a layer of RTV silicone rubber all over the spoke ends inside the wheel center, inboard and outboard. When the RTV has cured (overnight) reapply grease to the splines and install the wheels.
The knockoff nuts should be tightened to 325 foot pounds. A special socket and torque wrench for this purpose is available from Stainless Steel Brake Co. If you must use a mallet, use a big plastic dead blow mallet filled with lead shot and really beat the nuts tight, being careful not to hit the fenders. Getting the wheels tight is important. It is not uncommon to find cases where the hub is so badly worn from an under tightened wheel wobbling around on it that the wheel can no longer be tightened correctly. In such a case the wheel is not far from stripping the splines under braking or acceleration in which case the wheel would just spin freely on its hub.TECH TIPS FOR MASERATI BOLT-ON WHEELS
Maseratis with bolt-on wheels need special wheel mounting attention as much as their knock-off wheeled cousins. Before mounting bolt-on wheels, it's a good habit to thoroughly clean the wheel and hub mating surfaces and apply a very thin coat of grease to the wheel mounting face. Clean the threaded studs and apply a thin, even coat of molybdenum anti-seize compound to each one. Install the wheel and wheel nuts. Snug wheel nuts down and then incrementally tighten each nut to 80-90 foot pounds. On 4 lug wheels, use a cross pattern. On 5 lug wheels, tighten every other nut incrementally as you go clockwise in a circle around the wheel center. Every 5 times you turn every other nut, you have tightened every nut in the circle. Do that about 4 times working up to 90 pounds and you have torqued the wheel correctly. The main reason for this method is to prevent brake rotor warpage due to uneven tightening while going through hundreds or thousands of heating and cooling cycles. Never let anyone install your wheels with an air impact wrench. If you care about the appearance of the wheel nuts and you don't have one of those fancy nylon lined wheel nut sockets, try the following. Clean all dust and grit from the wheel nuts. Take the correct size six point deep socket, preferably one with "flank drive" (such as sold by Snap-on) and clean any grit that might be on the inside. Cut 2" squares from a plastic bag, place a plastic square over one of the wheel nuts and push the socket on to the nut. Have an assistant push on the brakes if need be and tighten the nuts in the previously described manner and to the correct torque using a new plastic square for each nut. Avoid using an extension between the deep socket and the torque wrench if you can. Extensions tend to absorb torque when they twist.
Winter is the time to think about putting your car right for the upcoming season. Although Wil DeGroot entitled the following piece "Storing Your Maserati," it really is a good guide for not only storing but also having the car in good condition in the spring.
STORING YOUR MASERATI IN WINTER
-Clean the entire car, even underneath and in the wheel wells.
-Fill the fuel tank to prevent condensation and add fuel stabilizer. Drive a few miles to get the stabilized fuel into the carburetors/injectors.
-While the engine oil is warm, drain it, and refill the crank case with fresh oil.
-If you change the oil filter, prefill the new filter with fresh oil before installing it to help prevent premature wear at startup.
-Change the brake fluid and coolant.
-Set the tire pressures.
-Park car on a sheet of plastic to keep moisture, that may come up through the concrete, away from your car.
-Remove, service, clean and charge battery. Clean battery tray and cables. Store battery in a cool, dry place off the cement floor. Check state of charge every month.
-Fill several old gym socks with moth balls. Put them in or near air filter, in tail pipes, in trunk, in heater air duct, under seats, and the in glove box. This will keep the rodents out. (Make a note to remind you where you put the mothballs.)
-Use a cotton car cover that can breathe. Never cover cars long term with plastic, particularly out of doors. Plastic will trap moisture under it and sunlight will bake it onto the paint.
-Once per month roll the car forward or backward a foot or so to prevent flat spotting the tires. This is particularly important for older cars with bias ply tires.
-If car is be stored for an extended period, you might want to consider jacking it up and resting the frame on stands. Just keep in mind that in the event of a catastrophe such as a fire or flood, your car will be difficult to extract quickly.
-A heated storage area is nice but it should be ventilated or dehumidified. Cold but dry is better than hot and humid. Remember that standard dehumidifiers don't work under 40° Fahrenheit. For low temperature storage the thing to have is a desiccant bag dehumidifier.Link to: Exoticars-USA.com
The following authored by club member Ivan Ruiz:
One sign of a worn engine is a rough running engine without power. But how can you tell the difference between an engine that needs a complete overhaul and one that simply needs a tune up? This tech tip shows the steps for performing a compression test and how to interpret the results.
Performing a compression test:
1. Remove the fuse for the fuel pump
2. Remove the high tension wire from the distributor (the wire that comes from the coil) and ground it. Radio Shack sells small jumper cables with alligator clips that are perfect for this task.
3. Remove all spark plugs.
4. Make sure the battery is fully charged in order to get consistent readings.
5. Insert the compression tool into the number one cylinder.
6. Make sure the throttle is fully open by depressing the accelerator pedal all the way. You will get inaccurately low readings if the throttle is not opened. This is a very common mistake!
7. Engage the starter motor several seconds until the compression gauge stabilizes .
8. Look for compression readings within 10% of each other. If one cylinder is at 160 psi and another at 90 psi, there is no way this engine will run smoothly.What if one (or several cylinders) have low compression?
If you find a low compression reading the car has a bad intake or exhaust valve (which is leaking) or a bad cylinder ring. The easiest way to further pinpoint the problem is to do a “wet” compression test. Pour some oil down the removed spark plug hole (enough to cover the cylinder—several squirts from an oil can should do the trick). The oil will temporarily seal the rings.
Repeat the compression test. If the reading increases significantly, the rings are the culprit (this is never a good sign). If the compression increased slightly but is still rather low, a valve is bad.Okay, it looks like one of the valves is shot, but is it the intake or exhaust?
To further pinpoint which valve is bad, the easiest way is to use compressed air down the removed spark plug hole and have an assistant listen to air hissing. If air can be heard in the exhaust pipes, the problem is the exhaust valve. If air is heard at the carburetor throat, the intake valve is leaking.
The next step is usually the removal of the head (the engine’s, not yours) and to secure a second mortgage because this will be expensive! At least now you know your mechanic is telling you the truth!It is not too uncommon to have your pre-1980 Maserati GT car backfiring either through the exhaust or through the carburetors. There are several tricks the home mechanic can use to tune Weber carburetors without expensive equipment. Keep in mind these tricks will not work if you are attempting to reduce exhaust emissions. For that task you will need an exhaust analyzer that can test for all the emissions requirements where you live. If all you are trying to do is to get your car running a little better, read on! The following is for cars fitted with Weber downdraft 42DCNF carburetors but some techniques also apply to the side draft DCOE inline 6 cylinder engines.
You cannot get an engine properly tuned unless it is mechanically sound. The engine needs to have consistent compression across all cylinders. Do an engine compression test and verify is healthy before continuing (see the previous tech tip on testing the health of your engine). A lot of engine problems are caused by the ignition system, so verify the spark plugs are clean, ignition wires in good condition, proper timing, etc. before messing around with the carburetors.
Okay, now it’s time to take a look at those Webers. First start the fuel pump for a few seconds to fill up the carburetor bowls. Remove the air cleaner so you can look inside the carburetor throat. Manually open the throttle and you should see a squirt of gasoline from each of the accelerator pump nozzles. Make a note of any nozzle not squirting. Next start the car and bring to an idle. Again look into the throats to inspect the accelerator pump nozzles and see if any are leaking. It’s not unusual to find several nozzles dripping fuel while at idle. To fix this problem, the accelerator pump’s diaphragms have to be replaced. Don’t panic this is an easy and rather inexpensive repair. The pumps are located on the left hand side of the carburetor, held in place by four slot head screws. Remove the screws and out will come the diaphragm and a spring. Make sure not to lose this spring as it will be reused. New diaphragms can be bought from a Weber supplier such as Pierce Manifolds (408-842-6667). I have a found NAPA part which also works fine and is priced at less than $8 each. It is best to replace all your diaphragms even if only one carburetor was leaking.
Once the diaphragms are replaced— and there is little else in a Weber carburetors that wears—it is time to adjust. Weber carburetors are infinitely adjustable by replacing jets but my suggestion is to leave the jets at the factory specifications unless you really know what you are doing (and therefore would not be reading this article!). This leaves us with only two adjustments: the float height and the idle mixture. Instructions for checking the float height are included in the owner’s manual but they seldom seem to be a problem.
To check the idle mixture I like to use a tool common to English car mechanics— a ColorTune. This is essentially a “see through” spark plug that lets you observe what is happening inside the combustion chamber while the car is running. I am surprised by how many people don’t know of this tool and am amazed by its simplicity.
Start by bringing the car to normal operating temperature. Stop the engine, remove a spark plug, and insert the ColorTune tool. Start the engine and observe the color of the combustion gases. Turning the idle mixture screw in (clockwise) should lean the mixture and make the gases turn white while turning the idle screw out should turn the gases bright yellow. Find the setting where the gases are burning a deep blue. Now you have finished the carburetor adjustments for this cylinder and are ready to do the rest.
At times, you will find the it is impossible to achieve a nice “blue burn.” This is an indication that something else is wrong with either the carburetor (dirt, etc.), ignition, or something really bad (valves, rings, etc.). If the engine has been popping, you will be able to pinpoint the faulty cylinder and see the popping through the ColorTune. Adjusting the idle mixture, you should be able to get a consistent burn and thus eliminate the popping.
If you determine the carburetor needs to be dismantled and cleaned, go ahead. The gasket kit for the 42DCNF is very inexpensive. However note that Webers have many small parts which all go back together rather easily. It is hard to mess them up unless you happen to lose a jet or two! Do one carburetor at a time so as to avoid this time consuming mistake.(Editor’s note: Rebuilding Weber carburetors is not as easy as it sounds. If you do not have some experience with this type of work it may be best left to a professional Maserati mechanic.)
SPECIFICATIONS FOR IGNITION TIMING, DISTRIBUTOR CURVES, AND CARBURETOR SETTINGS FOR 4.9 LITRE GHIBLI AND BORA ENGINESby Stephen Swain (from a discussion on Doug Holtsinger's maserati@yahoo.com discussion group)
A question from John Harden on the proper static timing set me off on some research on the 4.9 liter engine as used in the Ghibli and the Bora, in the US (smogged) and Europe (unsmogged) versions. I had always been slightly confused on this subject, especially as to specific carburetor settings and as to whether the same basic parts had been used. Curling up with the parts and user manuals, and US supplements, I arrived at some very certain conclusions (all challenges will be accepted, especially as it moves our combined knowledge base forward). So, here goes:
Both the smogged (US) and Euro versions of the 4.9 liter engine use the same basic engine—to include the heads, the camshafts, the distributor, and the carburetors. The only real differences were in the static timing, the distributor curves, the camshaft timing, and two carburetor pieces/settings. That is it. I believe that any smogged 4.9 liter engine can be set to Euro standards with a few adjustments. A word of caution, however – no adjustment should be made individually. They must be made as a whole if you are to receive any benefit. Don’t bother with just one or your car will probably run the worse for it.
Distributor: All the cars used the Bosch ZV2/30V2 distributor. Differences were in the static timing and in the distributor curves. All US models should be set to a static timing of 0̊, Euro models are to be set to 10̊ to 11̊ BTDC. All models, Euro and US, should reach a full advance of 38̊ – 40̊. The curves for the three distributor variations are shown in the diagrams contained in the below Acrobat document (see link).
The US model is retarded at idle, but rises rapidly after that, matching the others at 2300rpm, and topping out at 40̊ at about 3800rpm.
But, then things get interesting – the distributor is the only place where I found the Euro Ghibli and Bora engine specs to differ. And they really differ as the total advance curves show. Off idle the Bora immediately gets a 3̊ advance over the Ghibli and keeps it until 2000rpm, when it takes a much gentler line, while the Ghibli just keeps going up. The Euro Ghibli reaches it max advance at 3000rpm, 11̊ and 1500rpm ahead of the Euro Bora!
I do not understand why the two Euro models would differ in this respect when all other settings on the two engines are the same. I would really appreciate feedback from anyone who may have insight as to why Maserati did this, or what the differences mean in output. Which curve will deliver the higher performance?
Camshafts: All models use the same camshafts: #67000 for intake and #67500 for the exhaust. Cold clearances are the same also: .28mm on the intakes and .47mm on the exhausts—producing dwells (on the crank) of 300̊ and 256̊, respectively.
The difference between the smogged and Euro versions of the 4.9 engine is only in how the cams are timed: US intake is at 38̊ BTDC while the Euro is at 40̊ BTDC. US exhaust is set to 65̊ BBDC while the Euro is set to 54̊ BBDC. For me, the opening degrees and dwell are the only numbers you need to know (as long as your cam is not overly worn). First, set your dwells to 300̊ on the intakes and 256̊ on the exhausts by adjusting the valve clearances. Dwell is the important number, not the clearance. Honest. After your dwell is set, then set the cam timing. Obviously all this is most easily done when doing a rebuild, but it can be done with the engine in the car. (Actually, I believe most people on this list can do this in the dark with a beer in one hand from what I have read.)
Carburetors: All the 4.9 engines use the 42 DCNF/14 carbs. The US version uses a fatter slow running correction jet needle, Ø 1.30 vs. Ø 1.20. The US float is set to 50 ± 0.5 mm vs. 48 ± 0.5 mm for the Euro models. These two modifications result in both a leaner idle and running mixture. Then comes the interesting stuff – the smogged Ghibli mentions “progression holes 0.7-0.9-0.9-1”. I have no idea what this means. Both the smogged and Euro Boras call for “hole n.4”. The Euro Ghibli calls for nothing. Any ideas? All comments appreciated.
Minor junk: The smogged Bora needs an n. 8 accelerator pump cam, while all the others use an n. 26. Having fooled around with these things, I don’t think it makes much of a difference. I would go with the n. 26.
The smogged models call for a smaller spark plug gap, probably to avoid fouling. I would go with whatever you can get away with, the larger the better.
Some US 4.9’s have an air pump to force after burning in the exhaust system. This item can be safely junked, no matter what. It may reduce some hydrocarbons but it also heats up the headers which is why the extra shielding is there.
Conclusion: So, that’s it. The smogged and Euro engines are basically the same, with variations in ignition and cam timing being the real changes. This would fit with Maserati’s technical and manufacturing abilities at the time. Anyone who wants a Euro engine can have one just by using the Euro specs. But you need to use all of them!
Also I hope I have set for the proper specs for the US 4.9 liter engine for all those who had questions. The manuals can be a real mess in this area. (For complete specs on all the cars see the following link)
I would really appreciate a better understanding of the difference between the Euro Ghibli and Bora distributor advance curves. It is the only area where the two engines differ and I just don’t get it. As I have both a Ghibli and a Bora I would like some help here.
Ghibli/Bora Specs/Charts in Acrobat format