968 timing
12-06-2005, 11:19 AM
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968 timing
I'm sure I'll find this when I read the chapter, but thought I'd get a quick answer here.
Cams are in but the caps are not tightened down yet. I need to set up the static timing before I can do that. There are red marks on one tooth of each cam sprocket pointing 30(ish) degrees off vertical. I'm guessing the engine was set up at #1TDC when it was disassembled so they're set up properly for reassembly:
How do we set up timing on this engine? I can feel for the #1 piston to hit TDC, but are there some other marks on the crank and block to verify? Where are the marks on the balance shafts? And are the cams set up in the correct position?
Thanks,
Cams are in but the caps are not tightened down yet. I need to set up the static timing before I can do that. There are red marks on one tooth of each cam sprocket pointing 30(ish) degrees off vertical. I'm guessing the engine was set up at #1TDC when it was disassembled so they're set up properly for reassembly:
How do we set up timing on this engine? I can feel for the #1 piston to hit TDC, but are there some other marks on the crank and block to verify? Where are the marks on the balance shafts? And are the cams set up in the correct position?
Thanks,
12-06-2005, 12:13 PM
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Bill, balance shafts should never be used to reference TDC. You have to make sure you use the pistons/crank to get that. Ideally, you can try a dial guage in spark plug hole for cylinder 1. Once you have TDC, make sure you use a flywheel lock to keep things intact.
The manual show you the cam positions for TDC. Obviously the lobes will be facing up at TDC for cylinder #1. Make sure you evenly tighten the cam followers or you can bend the dowel pins. Each follower is marked for its position from 1 through 8. Their orientation is critical as well.
Once you have the cams/cam pulley aligned, then to work on the balance shaft. There is a great writeup at clarks-garage for it.
Raj
The manual show you the cam positions for TDC. Obviously the lobes will be facing up at TDC for cylinder #1. Make sure you evenly tighten the cam followers or you can bend the dowel pins. Each follower is marked for its position from 1 through 8. Their orientation is critical as well.
Once you have the cams/cam pulley aligned, then to work on the balance shaft. There is a great writeup at clarks-garage for it.
Raj
12-06-2005, 08:10 PM
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Bill It's very important that you set the cams in the chain with the proper orientation IIRC the manual will tell you the number of links on the chain between the 2 cams and the correct direction the cam lobes will be pointing on the number 4 cylinder.You must get this right before you install the cams into the head and install the tensioner in between the chain and the cams.If you need more help just post and I will look it up some of Porsche's instructions are just over the top.
12-07-2005, 02:22 PM
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Originally Posted by 968TurboS
Bill, balance shafts should never be used to reference TDC. You have to make sure you use the pistons/crank to get that. Ideally, you can try a dial guage in spark plug hole for cylinder 1. Once you have TDC, make sure you use a flywheel lock to keep things intact.
The manual show you the cam positions for TDC. Obviously the lobes will be facing up at TDC for cylinder #1. Make sure you evenly tighten the cam followers or you can bend the dowel pins. Each follower is marked for its position from 1 through 8. Their orientation is critical as well.
Once you have the cams/cam pulley aligned, then to work on the balance shaft. There is a great writeup at clarks-garage for it.
Raj
The manual show you the cam positions for TDC. Obviously the lobes will be facing up at TDC for cylinder #1. Make sure you evenly tighten the cam followers or you can bend the dowel pins. Each follower is marked for its position from 1 through 8. Their orientation is critical as well.
Once you have the cams/cam pulley aligned, then to work on the balance shaft. There is a great writeup at clarks-garage for it.
Raj
Cam followers? You mean the bearing saddles (caps)? I snugged them down a bit at a time as in the Ferrari cam replacement procedure. Ferrari cams are somewhat brittle, and have been broken by improper tightening. I 'assumed' these were the same.
Cams are in (they were in the correct position) and torqued down after I got #1 to tdc. All is well so far.