Cam timing for dummies...

All cam marks should line up at TDC 1-4. If the marks line up, everything could be ok. Or not. If they do not line up it can have several reasons, one of them being that the cams have been welded/ground in the past.

Draw a valve lift curve with the help of a dial gauge and a degree wheel. You will enjoy the work and will be sure what your cams are supposed to be set.

Regards
Harry

 

How "not even close" are they? Are they off by 45 degrees? Are they off by 180 degrees? Off by 180+ or - 45 degrees?

 

start here:
http://ferrarichat.com/forum/showthread.php?t=148604

 

Birdman has a Mondial that had the front bank 180 out of time, and it ran perfectly. The very fact your car ran okay tells me that whatever you have found is not an issue of any great importance. Rotate the engine 1 turn to bring it up on PM-1 again (so your rear cam index marks are not aligned) and look to see where the front marks are.

A four cylinder inline is possibly the only engine this would work on because of its firing order. You probably have seen the front bank is also numbered 1-4 on the cam cover, and realise that #5 is technically #1, front bank. By running the front bank 180 out, #4 (#8) becomes #1. Whoever worked on it last probably just flipped the plug wires around.

 

The cams cant be very far off or the engine would run horrible, or not at all. I would cerfully rotate the engine until you see the cam marks coming up, then start watching the flywheel. Assuming you have the plugs out, you can rotate the flywheel very easily by wedging the starter teeth with a screw driver. This way you can watch the cams index marks while simutaneously watching the flywheel. I would seriously want to know where they were timed before further disassembly.

 

It is so hard to see the front bank. I see you have the engine lid off. I also pulled the pins on the trunk lid and removed the carpet and then worked from the trunk of the car a bit. Just a thought, it might help.

 

Cool. Then I assume you have the companion thread on degreeing too. This is what I had hoped. Most mechanics do not degree but use marks only. I hope that DIY'ER's like you would raise the bar. Good job...keep going.

 

When I degreed my first engine, I found the TDC index plate (flywheel timing register plate) off 3 degrees retarded (late). The P6 cams index marks were all spot on with the valve timing I chose (308GT4LM). The second car I had to triple check to verify my work. Not only was it also off 3 degrees on the TDC index, but to get the valve timing I wanted, the rear intake cam index mark needed to be misaligned about an 3/32 inch to put the cam in correct timing. That puts the index over 20 degrees advanced, which if I had just aligned the marks, the rear intake would have been over 20 degrees late (retarded). the front cams came out looking pretty close, and the rear exhaust is too, but not one single cam out of the four was really lined up exact. In fact, both engines need thier index plates slots ground a bit to slide over enough to align.

Many dont stop to consider that the only physical mechanical difference between the early euro car and the early US car, was a 4 degree difference in valve timing. Valve timing degrees are read at the crankshaft, consisting of two full crankshaft rotations covering 720 degrees. Because the camshaft at the index flange is only about 1.25 inch in diameter, 1 degree crankshaft resolves to the index mark moving .005". 4 degrees amounts to moving the mark .020". which isnt very darn much. And if, as in my case, the TDC plate is off 3 degrees, and the cam index marks are off over 20 degrees, your only going to get further out of whack when you try to time the ignition and balance the carbs. The true balance begins with valve clearances being "equal" and then timing the cams to be equal to each other. Regardless of where you put the rear bank valve timing, make the front valve timing match it as close as is humanly possible.

So Jim, have you found those front marks yet?

 

Where are you going to stick that magnetic stand?

I was hot to buy a degree wheel as well and someone convinced me not to. I photo copied his. Now I make a photocopy enlargement as big as will fit in the engine space provided and paste it to paperboard. It also allows me to make marks and notes on the wheel to keep stuff straight. I do have to go to Kinkos to make wheels bigger than 8.5" though.

 

Steel plate across cam studs. Actually, I tried this, and decided it's just easier to use a piston stop. So that's what I plan to do.
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I did the same. Just a note that I didn't rely on the magnet. Note the C clamp holding the magnet in place. Even small movements of the base equal giant movements of the dial!
I also used a piston stop to find TDC as well as the meter. The piston stop was way easier, especially working alone. I just removed the ceramic from a plug and threaded the hole for a bolt.
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I was trying to figure out how to use the dial against the piston, but in the end I just made a simple piston stop. You can make one by knocking the guts out of a spark plug and threading the inside for a piece of threaded rod. You then install the plug body into the hole, and carefully thread the rod (I rounded the end a bit) down until its touching the piston at TDC. Now back the crank back a few degrees, and screw the rod down against the piston, such that when you turn the crankshaft (gently here as your not trying to drive the piston into the rod) the rod stops the piston and your flywheel stops a few degrees from TDC. Now you rotate the engine in reverse rotation, and slowly bring the piston up on the other side and come against the rod. The flywheel now stops on the opposite side of TDC. The middle between the two stops is TRUE TDC.

While the process seems crude, is so exact that inboard and outboard boat engines and aircraft engines are timed the same way. At the power levels those engines run at, often at 100% power continuous, you want every available HP you can get without burning up the engine, and a dial indicator, in this instance, just is not quite as exact. The indicator rod wants to dance around on the piston, and there is carbon crud down there to throw off your readings. Pressing the piston into a heavy steel stop with some moderate force is just more accurate.

What did you find on your front cams??