View Full Version : Installing engine top dead center

07-17-10, 06:20 PM
Question. Does an engine need to be at top dead center to install it. I am of the understanding that this is only to set timing. After that the crank can b rotated however. Also. Why are there two marks on the cams? Li le and ri re. I assume that the cams can be interchanged to exhaust or intake respectively. Just want to verify what I've been told

Mark C
07-17-10, 06:49 PM
LI,LE = Left Intake, Left Exhaust, RI,RE=Right Intake, Right Exhaust. With the engine at TDC on the no, 1 cylinder AND the timing marks on the crank timing gear, and the intermediate timing gear aligned you install the timing gears onto the cam with the appropriate slot over the pin (I for the intake cam, E for the exhaust cam) on the cam and position the pin 90 degrees from the surface of the head (except some 2000 cams which have the pins in the wrong location).

Are you asking if the cams can be physically be relocated so that an exhaust cam is an intake cam? If so the answer is no, used exhaust cams can't even be swapped from one head to another because of the wear pattern on the lifters (or followers). Intake cams can't be swapped at all since the left intake cam has the water pumpt drive on the end of it.

07-17-10, 07:03 PM
Ok. I didn't think they could be swapped. I knew what the li le re ri stood for. The question was why do they include markings for intake and exhaust on the same cam? Or that's what I intended to ask.

Next I just wanted to know what the reason for setting a timed engine at top dead center would be. I don't understand why it matters what position the rotation of the engine is in when installing it. Is this not what the cam and crank shaft position sensors are for?

Mark C
07-19-10, 10:10 AM
You can use the cam gears on any cam as long as you line up the slot with the letters above it and it matches the cam your putting it on. If the gear has LE above one slot, and LI above the other slot, you put the LE labeled slot on the gear on the left exhaust cam pin, OR you put it on the left intake cam with the LI slot on the cam pin. either way works, just don't get the cams or the gear positions mixed up or you'll be replacing valves. The reason you put the engine in on top dead center with the timing marks aligned on the crank and intermediate drive sprockets is you can't see those marks with the engine in the car. This only applies if your putting the timing chains back on after the engine is back in the car, if you have a completely assembled engine with the cam gears inplace and aligned, it does'nt matter what position the crank is in, everything is locked together at that point.

07-20-10, 03:49 PM
Thanks. That's what I thought. Thanks for clearing that up w me. I didn't think it mattered where the cylinders were rotated to after chains were all back on theengine