Maserati 3500 GTi, Sebring, Mistral and others engine

Hello everyone It's my second post here, so...it's good time to say hello.
I would like back to life one of the 3500 GTI engines and other mechanical parts from this Maserati therefore, I'm looking for every workshop manuals, article, books, everything what can be useful during the restoration. Of course, I wisited the Ivan's page and found a lot of good info about engine parameters, injection system etc.
However, I need something like "how to do it", that's mean info about methodology which is or has been used in workshops. Particularly needed info about ignition timing and settings of the camshafts.
If someone has something that can expand my and other chat users knowledge, I will be grateful for sharing

Best regards, Tig.

Ps. If something is wrong with my english, I do ask for your understanding

 

Top Dead Center (TDC)

Before you attempt to do any ignition timing, you need to make sure that top dead center is identified. If your engine already has timing marks you can skip this section. Top Dead Center may be identified on the engine as “PMS”.

For reasons I could never understand, many 6-cylinder Maserati engines do not have timing marks. Finding TDC is not that difficult and you can use several techniques.

The most accurate is to use a dial gauge. Remove one spark plug from each cylinder to make it easier to hand rotate the engine. I usually put the car in 5th gear and push it to rotate the engine. Remove the distributor cap so that you can see the ignition rotor. Rotate the engine until the rotor is pointing to the #1-cylinder wire. The #1 cylinder should be near the top of its travel. Now insert the dial gauge and zero it out. Gently rotate the engine forward and backwards until TDC is found.

If a dial gauge is not available a long screwdriver may be used. Once inserted, put a mark on the screwdriver where it meets the top of the cylinder head. You should be able to see the mark move up and down, stop when it reaches it highest position.

A simple tool that I have found very useful over the years is an adapter that will screw into the spark plug hole and a hose is attached to it (see photo). One of the things you want to verify is that the piston is on its power stroke. This is when both intake and exhaust valves are closed, and the spark plug fires. Hand screw the adapter with a hose and blow air with you mouth. You should feel a lot of resistance. If not, then either the distributor is 180 degrees out of phase or there is a bent valve.

You can also use this simple tool to help you find TDC. Place the hose against your mouth and hand rotate the engine. As the piston moves up you will feel air, as it moves down you will feel vacuum. The tongue is very sensitive

Whichever method you use, make sure to mark the harmonic damper and a corresponding mark somewhere on the block which will be accessible with a timing light.

Ivan
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Static ignition marking

The Mistral owner’s handbook calls for a static ignition timing of 8 to 10 degrees before TDC (BTDC). Not sure if this is true for all the inline 6-cylinder engines therefore it is best to check the manual of your model. I will use the Mistral specs in this example. To set static timing it is helpful to put a second mark on the harmonic damper indicating its location. I will use 9 degrees BTDC.

Use a string to measure the circumference of the harmonic damper. This length represents 360 degrees. Therefore the 9 degrees mark will be located at a distance of, 9/360 multiplied by the length, from TDC. Make a second mark on the damper.

Ivan

 

Setting ignition contact point gaps and phase

The Maserati inline 6-cylinder engines have two spark plugs that fire simultaneously. The distributor has two contact points, each controlling its own coil. The engine will run with only one coil, but you will feel the loss in power.

It is best to remove the distributor from the engine when replacing the points. Before you remove the distributor make a note of the normal direction of rotation. I normally use a Sharpie pen to mark an arrow on the distributor so that I do not forget.

Start by physically replacing both points and setting the gaps to what is specified in the owner’s manual of your model. For a 3500GT the gap is .4mm (.016 in).

The next step is to phase the contacts so that the spark plugs fire more or less simultaneously. I like to have one spark plug fire about 2 degrees after the first one, that way there is a longer burn.

I phase the contact points using two multimeters set to the “tone” setting, which sounds a tone when there is continuity. You can also use a battery with a couple of light bulbs.

Place one lead of the multimeters on each of the studs where the coils are normally connected, and the other lead on the body of the distributor. Hand rotate the distributor in the normal direction of rotation and listen to the tones. A coil charges up when the ignition points are closed, and the spark plug fires the instant the points are opened. What you want is to have one contact points open and the other immediately follow. Once you are satisfied with the phase recheck the gaps as they might have changed.

Ivan

 

Ignition timing

Start by setting the static timing by rotating the engine to the 9 degrees BTDC mark. Insert the distributor and make sure the rotor is pointing to the #1 cylinder. Rotate the distributor until the contact point just opens. A multimeter set for tones is very handy for this.

I like to double check by blowing some air into the #1 cylinder and verifying that both valves are closed, indicating the cylinder is in the power stroke.

Re-install the spark plugs and start the engine, bringing the engine to a low idle (600 rpm). Use a timing light on the #1A and then on the #1B spark plug wires to verify that the distributor was set correctly. At this low RPM there should not be any advance therefore both coils should be firing at about 9 degrees BTDC. A few degrees difference between A and B is normal and desirable.

The next step is to check the advance curve. Below is the advance curve for a Mistral, make sure to check the curve for your distributor as it may be different. On this distributor advance starts anywhere between 600 and 800 RPMs. At 1100 RPMS there should be about 11 degrees of advance, for a total of 20 degrees. Full advance is 15 degrees, for a total of 24 degrees. Best way to check advance is to use a timing light that lets you dial in the advance. In this example you would set the timing light to 24 degrees and the TDC mark should be aligned when the engine is above 2500 RPMs.

Ivan
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Ivan, thanks so much for this guide. I didn't understand what was going on in this diagram before. I know this method with light bulbs and gauge (I using it when i seting the motorbike ignition ) but adapter using a hose - it's simple and great.


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Acording to the info which I found (of course if I understanding it corectly), the static timing is 12 deg. before TDC. When I checking it using a timing lamp, I must add the value from diagram to 12 deg, and set total value on lamp and mark in on flywheel or harmonic damper. Tell me if I'm wrong please.

But what in case when we must take off head, crankshafts, chain and completely disassemble the engine? I fund this data.


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What is the way to use this parameters to correctly set position of the camshafts relative to the crankshaft?
Thinking... When the head is out of the engine and valve's clearance was succesfully set, Should I turn the camshaft to the position when lift of the inlet valve on first cylinder is 1 mm and make the point on inlet camshaft and bearing. Should I proceed with the exhaust camshaft in the same way?. Is the piston on first cylinder should be in TDC when the exhaust valve is completly open on the exhaust stroke? To much theory...
Is there any service method for this without using special locks?

 

Sorry for my second post, but i can't edit this above anymore.

That was early morning when i writing it... This is simple way to make a colision with pistons. My wrong way. So the questions is:
Are there any factory marks on the camshafts that I have not seen?
If not, how many deg. before/past TDC the valves should start opening and closing?

 

According to your last post, on your engine the static timing is at 12 BTDC and the distributor has a full of advance of 30 degrees, for a total of 42 degrees. There is most likely a graph in your manual, similar to the one I provided for the Mistral, that shows the amount of advance relative to the RPMs. With your timing light you should see 12 degrees at very low RPMs and the amount of advance increasing up to 42 degrees at high RPMs.
The Mistral manual indicates a total advance of 24 degrees and this one is 42 degrees; that is a very significant difference even if they use a different distributor. I hope there is not a typo in one of the two manuals. Perhaps someone else can shed some light on this.

Ivan

 

The factory normally marks the cams. Those markings are rather faint and sometimes difficult to find. I do not recall if the markings are on the power or exhaust stroke, but they should be visible when the chain link is visible. In other words, hand turn the engine to TDC and if the chain link is visible then look for the cam marks.

Perhaps someone else can explain the setting of the cams using the valve lift method since I've only used the factory markings.

Ivan

 

That is strange. The graph from book for 3500GT and GTi shows almost the same value that we can read on graph from Mistral ( ~12 deg around 1100 RPM). Is there a mistake somewhere?

Below graph from 3500's manual:
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Edit:

I will find the marks against, when the head and camshafts will back to me from regeneracion. But the second method is very interesting for me, cause I never before use it.

 

I think the discrepancy is that the graph is done with the distributor mounted on a distributor machine, where one revolution equals one complete turn of the distributor's rotor. As you probably know, an engine crankshaft rotates twice for every turn of the distributor. I was wrong saying the Mistral advance starts at 600 RPM; in reality the advance starts when the engine is spinning at 1200 RPMs (and the distributor at 600 RPMs). The total advance, as read with a timing light on the harmonic damper, is therefore the static advance plus 30 degrees; which in your engine is 42 degrees.

I currently do not have an inline 6-cylinder Maserati. It would be good if someone can check the full advance of their engine at high (4000) RPMs .

Ivan

 

I would be very interested in leaning how to set cam timing using the valve lift method. Please post a tutorial once you figure it out.

Ivan

 

In one of the topic's I found this info:

Thats look's on Italian language. I think that te meanings of symbols are: A.A - Begining of the inlet valve opening (begining of the suction stroke), C.A - finish of the inlet valve closing. A.S - Begining of the exhaust stroke.... C.S - end of the exhaust stroke. I have no idea whats mean number "# 48377" and similar, and others dimensions...[/quote][/quote]

 

[/quote][/QUOTE]
The number 48377 refers to the cam's part number. As your previous past mentions, most 3500GTi had inlet cams #48377 while some were special ordered with #48137. Similarly, the exhaust cams had different numbers and therefore different valve lifts. If I recall the part numbers are clearly visible somewhere on the cam.
As you, I have no idea what all the other numbers mean or how to take measurements.
Ivan

 

Ivan, most 3500's have the #48377 cams for both intake and exhaust. The intake cam is marked ASP and the exhaust cam is marked SC. These markings are very hard to read because they used the same electric pen that was used on the timing marks.
Three sets of cams are listed in the 3500GT Use and Maintenace Manual. The standard was the #48377 set. There was also a performance set, which we used to call 3/4 race and then the high-performance cam set. These have higher lifts and different durations. I have only seen one set of the 3/4 race set. I guess you could ask for this from the factory as an option if you knew it existed.
Larry

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So that looks the "last dimensions" from my last message is tappet lift (in).

 

There is much I do not understand about all these measurements and which tools to use to measure them and how to set it all up. That is why I figure it is best to use the factory marking as I am assuming whomever initially build the engine knew what he was doing, and as long as I am using his marking it will be alright.

Ivan

 

The setup to accurately measure the cam timing is not that difficult. You need a degree wheel and a dial indicator. The degree wheel is bolted to the crankshaft pulley with 0 degrees at TDC and the dial indicator is mounted on a cam tower with the indicator plunger on the tappet. You can also see if the cam is worn very quickly with this set up. Ivan you are right the cam markings are usually accurate if everything is original. But the width of the markings on the cam can lead to a error in the timing if not accurately aligned with the mark on the cam tower.

 

Ok I have a little free time and a little theory. According to data from the carnutz, the standard valve timing should look that:

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Very much sorry for quality of my handwriting and drawing but I am not a artist
Maybe it's will be useful to someone.
And the most important: if something is wrong with diagram please write me here or on the PM.

 

Hello again. I have two questions to users, fanatics and mechanics 3500 engines.
The first of my problem are springs from ignition distributor rotor. One of them is thiner and longer than second. It's factory original solution or somebody changed it? Image Unavailable, Please Login Image Unavailable, Please Login

The second question applies the conection rod bolst. Does someone know/have info where I can find info about lenght and lenght tolerance of this bolts or have dimension whith I need?

 

Sorry for second post, but edition is impossible now.
Does anyone know where in Europe could I find new conrods bolts and nuts for 3500's family engines?

 

I understood that the second plug fired three degrees behind the first for a longer and more complete combustion. This was from my father and have no idea where he got the information, but it wasn’t the kind of thing he would make up.

 

I have never seen anything official from the factory but it does make sense to set them a few degrees apart. If the specs call for 10 degrees BTDC, I set one at 9 and the other at 11.

Ivan

 

Were I you I would spend some time search on here for threads about rebuilding Marelli distributors. There have been more than a few over the years. You distributor is the same basic construction as the ones on the V12 Ferraris and Lamborghinis. Some references to professional rebuilders can be found in those threads. When I did mine over 10 years ago these parts were quite hard to find but that may have changed now. The rest of the information in those threads will be quite helpful as v12 or straight six the advance mechanism works on the same principles. It's not a design I think very much of.

 

I’m studying up on this topic because I may need to reassemble a 4L Mistral engine that someone else disassembled. Does this engine have CW rotation?