Degree Wheels

I was thinking about taking the engine out of my 78-308. I wanted to rebuilt the motor myself, then put it back together. Being a 2valve car I am thinking it would not be hard to correlate the pistons with the valves. I have seen degree wheels, but for the life of my I don't know the procedure on how to use one. I know you place it on the crank. Does someone have a procedure on how to use these things.

 

There are some Ferrari specific procedures that you can search FC to find. On UTube there are some videos too. Some use lobe centers, but it seems the more common way for a Ferrari is initial valve opening. Attached are pictures of my degree wheel in place. Mine was glued to a piece of poster board then attached to the crankshaft with rubber cement. The problem on the Ferrari is that you need a big hole in your degree wheel to get a socket in to turn the crank the wheel downloadable from this site is great because you can print it any size you want and it has concentric circles. This one is in crankshaft degrees (needed to attach to crankshaft) verses cam degrees of rotation (which are ½ of crankshaft degrees). My pointer is made from a stiffener from an old wiper blade; it was flat and rigid. The bigger the degree wheel you use the more accurate your measurements will be. I used and indicator to find TDC, but I think the bump stop method would be faster and more accurate; however you need to find TDC with old timing belts. For degreeing the cams it would be best to get some undersized shims; using an indicator to determine valve movement is a PIA. It would be much quicker to have some undersized shims on hand and just feel valve movement.
Degree wheel site http://photos.passado.com/p01/8E/63/92ed191889f04a7596f1cc955a1b5039_o.jpg follow the directions on downloading else you will get a small, pixelated copy.
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Here you can copy and laminate this degree wheel.
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Yo Mike,

Do you have that in PDF?

 

Thanks Mike,

I will most definately use it. This might sound stupid, but when you degree cams, do you first turn the degree wheel, then insert the intake and exhaust cam, and then adjust the loops for clearance, along with the shims. I guess what I am trying to understand is that once you place the degree wheel on, the pistons go up and down when you turn the crank, put you have to be careful because you don't want the pistons to hit the cams. So I guess you first turn the crank to the proper setting, then install the cams. I hope I am making myself clear, and not confusing anybody.

 

Barnone

First, You install the cams using the factory markings on the cams, the crank, the pulleys, the cam belts, the tensioners. The factory markings are good enough to ensure that pistons and valves don't meet in a dark alley.

Then you use the degree wheel to fine tune the cam timing. If they are off at all, they are only off a little bit.

 

Well thats what did not make sense to me. Thanks for clearing that up. Isn't it a waist of time then to turn the degree wheel and basically write down at what degree intakes and exhausts are opening and closing if you aren't really making any changes. Why even use a degree wheel.

 

maybe this will fill some gaps and get you started

http://ferrarichat.com/forum/showthread.php?t=148604&highlight=cam+setup

http://ferrarichat.com/forum/showthread.php?t=148917

 

You know, I wonder if you can really tell the "real world" difference between just lining up the cam/flywheel marks,and using a degree wheel?

 

What's with degreeing the cams right now? Was there something wrong with your engine? Or are you just doing it to be sure things are correct?

 

I had a plan to rebuild my engine. But I always really thought that if you align all your cam marks correctly, then you would be OK. But then I looked in degreeing cams, and thought that was a process needed to assemble your motor. I don't understand what purposes it really serves unless you wanted to fool around with your timing.

 

I do have one concern about downloading and printing off a degree wheel. The acuracy of the paper degree wheel is only as good as the printer. There is always some distortion between an actual image, and the printed copy. I made a degree wheel using CAD and plotted it out using a x-y axis plotting machine. I then printed out that same image on a xerox machine, and there was indeed some variation between the two. The plotter was VERY acurate, but the xerox copy would have some areas that lined up good, and other areas were a half a degree or more. Just be aware of this possibility.

 

The purpose of degreeing or Indexing a cam is to place the cam
in the exact place in reference to the crankshaft that the factory
engineers intended. The marks are sometimes not 100% correct.
In most street cars there is not much benefit,and is not necessary.
BUT this is a Ferrari, why own such a car
and not put it together the way it was intended? It will run,
but who knows how well.

Thats just me

 

If you don't want to make your own, you can buy a degree wheel from most of the major auto parts stores, race shops or even on Ebay. Just Google "auto parts degree wheel" and you'll come up with hundreds of them. And don't worry about the hole in the middle. On my car and on a friend's 308 QV, we just inserted the big socket for the crank onto the bolt before mounting the degree wheel, and just put the socket extension through the smaller hole in the center of the degree wheel and left the socket there until the job was done and the degree wheel removed.

On my friend's 308, he had three threaded studs welded to his crank damper to hold the timing ring for his Electromotive, so we mounted the degree wheel to that. On my 308, we just used double-stick tape to mount it. We used a piece of coat hanger wire to make a pointer, which was attached to one of the bolts on the engine. It worked perfectly on both engines.

This has been discussed in many other threads, but remember, the marks on the cams are very small, and a slight variation on setting up the cam based on those marks can mean that you are anywhere from a couple of degrees to 5 degrees or more off on the cam timing. The width of the groove on both the cam and the cap is 3* each, so if you miss the alignment, you could be 5 or 6* off. It is a starting point, but degreeing the cams is the only way to be sure you are spot-on.

 

Learning how to degree cams on your own on a 4 cam motor is not a good idea.

As to why you do it on a Ferrari. Ferrari cams are notorious for being badly marked. A single cam motor will always have the valve events correct to one another and that will assure a reasonably good running motor as long as it is not too far off in total but a multi cam motor the valve events can get rather far off from each other and that gets to be a mess in a hurry.

For the person that stated it would probably be OK to just use the marks here are some pictures.

This is a 456 cam that is correctly timed
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A TR at spec
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A TR 6 degrees off.

Way more than required to overheat a cat.
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A TR 5 degrees off. Again, more than enough to overheat a cat.
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A C4 with correct cam timing.



So, do you want a car that runs correctly or one with check engine lights, cat temp lights, overheating burned out cats, fails smog, and carburettors that just do not respond well to adjustment?
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And don't mess around with POS degree wheels made in a printer. They just are not that expensive to buy. Here is a good one for use when the motor is out.
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Amen...

 

Brian,

Those pictures you posted make the point that I was trying to get across very well. Unless you degree the cams, you have no way of knowing for sure whether the mark on the cams is accurate or not. And the difference between dead-on and 6 degrees off ain't that much when you look at the marks in your pictures. But most shade tree mechanics would look at the marks being off and question the settings, or as in the one that was 5 degrees off, simply set the cams to the factory marks and assume the timing was correct, even though it was well beyond factory tolerances.

 

Thanks for the responses, I guess the question I have is lets say that after testing with the degree wheel you find that the information you get out of degreeing the cams do not match factory specs. How do you adjust to factory specs.

 

Based on your posts I think you have a general conceptual misunderstanding. The marks are "assembly marks" Using them your care will run and pistons will not hit valves. The factory specification for timing might equal the marks and may not. Setting timing with dial gage and degree wheel to factory spec the marks can be ignored.

 

RD,

Can you give us a sence of "what if"?

int or exh cam off 5 degrees = burnt cat?

7 degrees car runs like cr@p?

10 degrees pistons hit valves?

A good seat of the pants driver would feel "??" degrees off?