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Hello experts, I am doing timing of 1992 Porsche 968.. from the manual I know that at 0.39 of tappet lift at cyl 1 intake, it should be at tdc(flywheel OTC mark)... Now I have set it at 0.39 for tdc & the cam sprocket rotated( without rotating camshaft) with crank rotated to tdc mark , but while I rotate crank for next round the cam sprocket notch mark is not matching with cover plate mark...if I match the cam sprocket mark with cover plate mark, I can not see flywheel OTC mark at correct position it goes 3 tooth further away( attached pic).
i have special tool for pressurising variocam & I am able to pressurise to 3bar & it is leaking, than I put check valve o-ring & it is not leaking air much( photo attached).
Please let me know what might be going wrong. At 0.39 I am at tdc ( flywheel mark is matching after the adjustment), but after further 360 degree rotation my cam sprocket notch is not matching with rear cover mark..
hope I am making sense
A little confusing what you wrote but if you rotate the crank 360 degrees I think the notch in the cam gear will be pointing 180 degrees away from the housing notch. Which is firing top dead center for cylinder 4.
There will be air leaking out of the Variocam unit when it's pressurized.
A little confusing what you wrote but if you rotate the crank 360 degrees I think the notch in the cam gear will be pointing 180 degrees away from the housing notch. Which is firing top dead center for cylinder 4.
Ok as per manual I have to rotate crank until I see 0.39 at intake valve tappet of cyl 1.. so I have to rotate the crank approx 360 degree to get this value... Now at this point the camshaft has been rotated 180 degree( 4 stroke engine so cam will move only half of cranks)...
now when I adjust cam sprocket at 0.39, than I rotate the crank again next 360 degree, so now the camshaft will have 1 complete round of 360 degree( please note until this point crank has gone 2 complete rotation whereas cam has been rotated only once).. so now at this point the cam sprocket mark is not matching up with the rear cover mark...
I hope that I made it clear
Hmm I'd have to rethink the whole procedure again since I did it a few months ago. Have you seen this? May help, kind of breaks it all down to the essentials.
Hmm I'd have to rethink the whole procedure again since I did it a few months ago. Have you seen this? May help, kind of breaks it all down to the essentials.
Your photo shows the FW mark is at the top of the bell housing. This is not where you set to #1 TDC. Use the notch at the bottom center of the bell housing! Look at the diagrams carefully.
Sometimes the notch in the cam gear will NOT align with the rear cover mark even though the cam timing is correct. The marks should be close, however. This is often the case when cam gears and rear covers are pulled from different engines. Further, the rear cover does not locate precisely, and can be rotated slightly with its 6mm fasteners loosened. If you are confident with your cam setting, just put a new mark (paint or whatever) on the cam gear and button it up.
Do make sure your dial indicator starts at zero when on the heel of the cam lobe, and make sure you're not mixing up the metric specs with US measurements.
Your photo shows the FW mark is at the top of the bell housing. This is not where you set to #1 TDC. Use the notch at the bottom center of the bell housing! Look at the diagrams carefully.
Sometimes the notch in the cam gear will NOT align with the rear cover mark even though the cam timing is correct. The marks should be close, however. This is often the case when cam gears and rear covers are pulled from different engines. Further, the rear cover does not locate precisely, and can be rotated slightly with its 6mm fasteners loosened. If you are confident with your cam setting, just put a new mark (paint or whatever) on the cam gear and button it up.
Do make sure your dial indicator starts at zero when on the heel of the cam lobe, and make sure you're not mixing up the metric specs with US measurements.
MM
thanks Micheal for the reply... The engine is out of car, so as per manual we can check tdc at top notch & if it is not out of car than we should go for the mark at downside inspection hole( also mentioned in San)... I have got the engine fixed, it feels fine at idle & test drive...
Thanks
12-10-2019, 03:17 PM
968, 1992 engine timing
