Help with finding TDC
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From: Lawrenceville, GA
Help with finding TDC
Changing my timing belt.
Stock cam gears.
My question is, where is TDC? As it is now, I can't get both cam gears and crank pulley to line up at the same time. I hear this is normal. When I put everything back together, should I try to line everything up or should I leave them off as much as they are now?
Stock cam gears.
My question is, where is TDC? As it is now, I can't get both cam gears and crank pulley to line up at the same time. I hear this is normal. When I put everything back together, should I try to line everything up or should I leave them off as much as they are now?
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Joined: Sep 2005
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From: Chicagoland
What about your oil pump? It runs the balance shaft. If you dont get that lined up also, you are going to have vibrations.
On the crank position sensor disk, there is a V cut into it. It is to be lined up with the arrow cast in the front cover at about the 10:30 position.
The oil pump has a dot that is to be lined up with the arrow cast in the front cover. It is geared to the front balance shaft which can be in two different positions even when the dot is lined up with the arrow. To make sure your on the correct phase on the balance shaft, spin the oil pump pulley and it will fall into a natural spot where it stops. If the dot is near the arrow, then its correct. If the dot is not near the arrow, it is not correct.
The cam gears get lined up to the valve cover. This is hard to do as the cams do not allow the gears to sit naturally where they need to be. You have to pull the valve cover off and use an open end wrench on the hex of the cam shaft to pull / push it into position. With the cam cover off, you have no reference marks. Its kind of trial and error till you get used to doing timing belts.
Be careful not to turn the motor over with the timing belt off and bend the valves. The 4g is an interference motor.
Did you also change your balance shaft belt?
On the crank position sensor disk, there is a V cut into it. It is to be lined up with the arrow cast in the front cover at about the 10:30 position.
The oil pump has a dot that is to be lined up with the arrow cast in the front cover. It is geared to the front balance shaft which can be in two different positions even when the dot is lined up with the arrow. To make sure your on the correct phase on the balance shaft, spin the oil pump pulley and it will fall into a natural spot where it stops. If the dot is near the arrow, then its correct. If the dot is not near the arrow, it is not correct.
The cam gears get lined up to the valve cover. This is hard to do as the cams do not allow the gears to sit naturally where they need to be. You have to pull the valve cover off and use an open end wrench on the hex of the cam shaft to pull / push it into position. With the cam cover off, you have no reference marks. Its kind of trial and error till you get used to doing timing belts.
Be careful not to turn the motor over with the timing belt off and bend the valves. The 4g is an interference motor.
Did you also change your balance shaft belt?
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I'm curious... if someone was building a race motor... would they pretty much ignore these marks and use a degree wheel and dial guage? If so, what reference points do you use? For example, for all camshafts, do they have a spec like where in crankshaft degrees peak lift should occur or that kind of thing?
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Johnboy1065
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Sep 17, 2005 12:36 PM
