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The 8v and 16v cam gear OD and tooth count is the same? The widths are different? The ID is different- what are the diameters?
Is the 928 S3 timing gear and 944S the same? Are they interchangeable?
I see from pictures some 16v [32v] timing gears have +/- adjustment. Does one have to degree in the cams when doing the timing belt? If so- is there a write-up somewhere? What about a list of valve events to degree in them?
The 8v and 16v cam gear OD and tooth count is the same? The widths are different? The ID is different- what are the diameters?
Is the 928 S3 timing gear and 944S the same? Are they interchangeable?
I see from pictures some 16v [32v] timing gears have +/- adjustment. Does one have to degree in the cams when doing the timing belt? If so- is there a write-up somewhere? What about a list of valve events to degree in them?
Thanks in advance
Pete
Crank drive gear + cam drive gear are larger on the 944S and have more teeth than the 8v.
16v belt is 1/4" wider than 8v and I "think" a different length too.
You would use the 944S belt drive and gears on the 944S cams, mounted to the 928 head.
There is some adjustment in the gear, yes, but don't know the degree range. I ended up getting a 16v-specific adjustable cam gear so I know how many degrees advanced/retarded I put it.
So if the top gear is a different OD then the bottom crank gear is a different OD so it will keep the same 1:2 ratio (1 turn cam to 2 turns crank)
Crap. I need a whole mess of parts I think now.
Just to get this straight... All of the timing belt gears, belt, water pump, idlers and tensioner need to be able to accommodate the wider belt and need to be from the 16v S/S2 motor?
The balance shaft belt system is the same correct?
Would you speculate that the additional valvetrain strain (springs, rotating mass, etc) on the belt is what nessessatated the added belt width and larger gear belt wrap?
So if the top gear is a different OD then the bottom crank gear is a different OD so it will keep the same 1:2 ratio (1 turn cam to 2 turns crank)
Crap. I need a whole mess of parts I think now.
Just to get this straight... All of the timing belt gears, belt, water pump, idlers and tensioner need to be able to accommodate the wider belt and need to be from the 16v S/S2 motor?
The balance shaft belt system is the same correct?
Would you speculate that the additional valvetrain strain (springs, rotating mass, etc) on the belt is what nessessatated the added belt width and larger gear belt wrap?
Balance belt system is the same.
Water pump + timing belt idler are the same, 8v vs 16v.
The cam and crank gears are 16v specific. I got my cam gear from 944online for really cheap, give him a call. I got the crank gear from Lart.
I think the wider belt is due to the DOHC strain, yes.
The larger crank gear is to match the larger cam gear, which was probably a carry-over part from the DOHC 928 engine released 2 years prior to the 944S.
The 8v cam gear does fit onto the 16v cam. I cross referenced the cam belt and found a 22 mm wide belt that is the same 117 tooth count. I am going to have to make a offset washer to hold the gear on at least... if it will even work at all.
I am not sure of the alignment yet, but when I get the s3 head next week I am going to mock up everything.
Random thing I just noticed...
I have both heads off a 928S3 engine.
On one, the chain tensioner oil feed is in the same place (exhaust side oil gallery) as the 944S.
However, on the other head, the oil feed is on the intake side...
I noticed that neither the 928S3 nor the 944S oil feed tube would fit, with the 944S chain tensioner mounted in the 928S3 head. Tube needs slight tweak.
But this "other side" head has a totally different tube altogether...
Random thing I noticed is that I have the left side 928S3 head, not the right. I have the left tensioner and the tube and also I have a pair of L and R 928s4 tensioners and tubes... hopefully something works.
I did not realize the port flange on the 16V heads is about 45*ish as the NA heads are 90*ish, hence the port spacing is correct but the port angle is way off.
Maybe this weekend if I can find time I am going to try to mock up the 16v head with the 8V gears and see if it is even possible to do.
Does anyone have the factory guide to setting the cam timing? Clark's garage does not have a detailed instructions on how to do it.
Side note- I am assuming the valve cover is magnesium? If so, is it safe to just chemically strip or sandblast and then paint?
Gonna have to mill off the 8v flange and weld on an angled 16v flange to use that manifold.
Gonna have to figure a way to securely attach that 8v gear to 16v cam...much easier to just use 16v parts there.
Cam cover is magnesium...928 guys soak them in vinegar before painting as it cuts off the oxide layer and sticks better.
The camshafts have sort of "pointers" cast into them near the chain...the two pointers should be aimed straight up at the cam chain, roughly centered on the chain links...counting the links being pointed at it should be 7 links across...and at TDC cylinder #1 intake valve should be like 1.4mm open.
Just picked up a few more cool parts. I just need the lower 968 power steering mount and stud with the o-ring for the tensioners swing arm to complete my 968 timing belt tensioner setup for this biuld. And a new bearing for the gear on the arm. Thanks John. Happy Easter to me. And I have a spare 16v crank gear now. Good stuff. I got a LR 951 header but the outside bolt hole needs to be enlongated in order to fit the head. It's only that one last bolt on the head. And I seem to have the 928 head that feeds oil to the cam tensioner from the opposite side of a 944S head. I wonder what problem that may lead to regarding oil presure to the tentioner? Why does Porsche have the oil feed to the tensioners on the lower side of the heads when installed on all the 944S/S2/968and 928's? Should I get the opposite head?
I have the oil line that fits. I don't have a water neck to check. My parts car didn't have one. You have the adapter for the water neck right? Because it looks like it should work. I'll check when I'm done with the morning Java.
03-07-2016, 07:50 PM
