# Camshaft Location



## supravan (Apr 24, 2004)

I have just rebuilt my SR20DET VCT and am not convinced with my location of the camshafts. I have installed them as per the workshop manual but as I rotate the motor the inlet cam does not start to open until the piston has gone past TDC. I always thought that the inlet cam should start to open just before the exhaust stroke had finished, or this may be different on turbo motors.
Could anybody provide me with a measurement at TDC of how much the inlet and exhaust valves should be open.
I also noticed that at the marked TDC that the piston was not quite at the top.


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## wes (Apr 30, 2002)

supravan said:


> I have just rebuilt my SR20DET VCT and am not convinced with my location of the camshafts. I have installed them as per the workshop manual but as I rotate the motor the inlet cam does not start to open until the piston has gone past TDC. I always thought that the inlet cam should start to open just before the exhaust stroke had finished, or this may be different on turbo motors.
> Could anybody provide me with a measurement at TDC of how much the inlet and exhaust valves should be open.
> I also noticed that at the marked TDC that the piston was not quite at the top.


I do not have those measurements but make sure you are looking at the motor when piston 1 is at TDC on the compression stroke, you could be concerning yourself with nothing. The other thing is why are you concerned with this, did you change the cams? If they were that far off you may see/hear the valves contacting the pistons etc....


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## supravan (Apr 24, 2004)

wes said:


> I do not have those measurements but make sure you are looking at the motor when piston 1 is at TDC on the compression stroke, you could be concerning yourself with nothing. The other thing is why are you concerned with this, did you change the cams? If they were that far off you may see/hear the valves contacting the pistons etc....



The cams have been reground back to standard. I have had quite a few race cars over the years and I have always found that in performance stuff the inlet and exhaust cams are slightly open at TDC to enable the exhausting gases drag a little inlet mixture in to give more power. I would of thought that the inlet would at least start to open at TDC.


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