S4 Cam Phasing Connundrum-RT Head
11-28-2016, 03:09 PM
#16
Rennlist Member
Thread Starter
BTW, Jim after some more research on the 9248 tool, I see that it is just the cam clamp for either removal or install of the cams, and not a profile tool. Apples and oranges. Rob Edwards has the tool and there are several pics and explanations on it. Here's one:
"Rob Edwards: This tool set is confusing. If you buy a 9226, you get 6 pieces - two cam hold-down blocks (9226/2 times two), two cam lobe timing templates (9226/3, driver's side and 9226/4, passenger side), and two threaded rods to locate the blocks. The blocks only work on S3 (85-86) heads. If you order a 9248, you get one cam hold-down block.
So to have complete set that'll actually work on an S4, you need 9226 x1, and 9248 x 2.
The best part is, you don't really need any of them. You can just back the cam caps off one bolt at a time (splurge for a Hazet 990-8 XZN socket, trust me) with an air gun, then make them finger tight again, then go around the head and loosen each bolt 1 turn at a time until the cam is released from the head."
The pics Rob posted were very helpful.
Thanks again for all of your help gentlemen. I can sleep a little easier. :-)
"Rob Edwards: This tool set is confusing. If you buy a 9226, you get 6 pieces - two cam hold-down blocks (9226/2 times two), two cam lobe timing templates (9226/3, driver's side and 9226/4, passenger side), and two threaded rods to locate the blocks. The blocks only work on S3 (85-86) heads. If you order a 9248, you get one cam hold-down block.
So to have complete set that'll actually work on an S4, you need 9226 x1, and 9248 x 2.
The best part is, you don't really need any of them. You can just back the cam caps off one bolt at a time (splurge for a Hazet 990-8 XZN socket, trust me) with an air gun, then make them finger tight again, then go around the head and loosen each bolt 1 turn at a time until the cam is released from the head."
The pics Rob posted were very helpful.
Thanks again for all of your help gentlemen. I can sleep a little easier. :-)
11-28-2016, 03:54 PM
#17
Developer
We have a variety of cam grinds, and have used the tool on all of them. As you have said, depending on the cam grind and profile you are testing, you may get a less-than-perfect fit of the tool to the cam, but it still is very useful and much more accurate than counting links.
Here is a link to our instructions with pics that show what a good and a bad install looks like:
http://www.928motorsports.com/instal...ile%20tool.pdf
Have a look at these pictures. Although the cam profile tool is not exactly the right profile for the camshafts being tersted - they still show very clearly whether your installation is a link too advanced, retarded, or "just right"
Here is a link to our instructions with pics that show what a good and a bad install looks like:
http://www.928motorsports.com/instal...ile%20tool.pdf
Have a look at these pictures. Although the cam profile tool is not exactly the right profile for the camshafts being tersted - they still show very clearly whether your installation is a link too advanced, retarded, or "just right"
11-28-2016, 03:56 PM
#19
Developer
In these pictures the cam profile tool shows the cam chain has been installed correctly
Note that the profile tool does not match the cam lobe perfectly. It doesn't need to. For the purpose intended, it is way accurate enough to be useful, and much more accurate than counting links.
IN AN IDEAL WORLD: there would be a cam profile tool made for every camshaft grind. But even Porsche did not do that - that would be wasteful. The profile tool shows clearly that you have the cam chains timed right or not, and that's all it is for.
PS: when we see a disparity between the "7 links" and the "profile tool" methods for camshaft phasing, we have learned to go by the profile tool. The difference was significant on the engine dyno, we have tried it both ways. Believe what the profile tool is telling you.
Note that the profile tool does not match the cam lobe perfectly. It doesn't need to. For the purpose intended, it is way accurate enough to be useful, and much more accurate than counting links.
IN AN IDEAL WORLD: there would be a cam profile tool made for every camshaft grind. But even Porsche did not do that - that would be wasteful. The profile tool shows clearly that you have the cam chains timed right or not, and that's all it is for.
PS: when we see a disparity between the "7 links" and the "profile tool" methods for camshaft phasing, we have learned to go by the profile tool. The difference was significant on the engine dyno, we have tried it both ways. Believe what the profile tool is telling you.
11-28-2016, 04:56 PM
#20
Rennlist Member
Thread Starter
In these pictures the cam profile tool shows the cam chain has been installed correctly
Note that the profile tool does not match the cam lobe perfectly. It doesn't need to. For the purpose intended, it is way accurate enough to be useful, and much more accurate than counting links.
IN AN IDEAL WORLD: there would be a cam profile tool made for every camshaft grind. But even Porsche did not do that - that would be wasteful. The profile tool shows clearly that you have the cam chains timed right or not, and that's all it is for.
PS: when we see a disparity between the "7 links" and the "profile tool" methods for camshaft phasing, we have learned to go by the profile tool. The difference was significant on the engine dyno, we have tried it both ways. Believe what the profile tool is telling you.
Note that the profile tool does not match the cam lobe perfectly. It doesn't need to. For the purpose intended, it is way accurate enough to be useful, and much more accurate than counting links.
IN AN IDEAL WORLD: there would be a cam profile tool made for every camshaft grind. But even Porsche did not do that - that would be wasteful. The profile tool shows clearly that you have the cam chains timed right or not, and that's all it is for.
PS: when we see a disparity between the "7 links" and the "profile tool" methods for camshaft phasing, we have learned to go by the profile tool. The difference was significant on the engine dyno, we have tried it both ways. Believe what the profile tool is telling you.
I'm going to leave it I guess. Thanks.
11-28-2016, 06:28 PM
#23
Developer
Chris,
I went back and looked at your original post and pictures.
1) you are not using our tool. That one in the pictures is not our product, so I cant vouch for it.
2) I'm guessing here (because thats not our tool) but that looks like the presentation of "half a link off"
To confirm before you tear it apart: run a compression check. If you get similar compression numbers on all 8 cylinders, your good. If the banks do not match, one set of 4 cylinders is consistently lower than the other bank, then it isn't right on the bank with the low compression.
I went back and looked at your original post and pictures.
1) you are not using our tool. That one in the pictures is not our product, so I cant vouch for it.
2) I'm guessing here (because thats not our tool) but that looks like the presentation of "half a link off"
To confirm before you tear it apart: run a compression check. If you get similar compression numbers on all 8 cylinders, your good. If the banks do not match, one set of 4 cylinders is consistently lower than the other bank, then it isn't right on the bank with the low compression.
11-28-2016, 08:10 PM
#24
Rennlist
Basic Site Sponsor
Basic Site Sponsor
The 5-8 side is so easy....everything is always by the book.
The 1-4 side is a horror story.
The cam tools supplied by Porsche work great on the '85/'86 cams, but are all but worthless on most of the other model engines (the GT cams will be the closest, because of the similar lobe centers to the '85/'86 camshafts, but the lobe centers are so far off on the S4 cams, they are not close enough to be of any use.)
Some clues....
First of all, it is very rare to "achieve" 113mm on 1-4 side of the '87 and later engines, with any of the factory cams. I've had engines as low as 110mm, with the cam timing spot on.
Secondly, there are cams that were incorrectly indexed when they were ground...and the lobe location is not correct. Everything seems correct, until the cam timing is actually measured.
The camshaft specifications are clearly stated in the Workshop Manual....with exact opening and closing events at a universal (German universal) 1mm of travel.
The ONLY way to do this job is to buy a degree wheel (or one of my front dampers that has degrees marked on it), figure out exactly where TDC is, and "degree in" the camshafts. Compare what your results are to what the cam timing should be....correct as required
The 1-4 side is a horror story.
The cam tools supplied by Porsche work great on the '85/'86 cams, but are all but worthless on most of the other model engines (the GT cams will be the closest, because of the similar lobe centers to the '85/'86 camshafts, but the lobe centers are so far off on the S4 cams, they are not close enough to be of any use.)
Some clues....
First of all, it is very rare to "achieve" 113mm on 1-4 side of the '87 and later engines, with any of the factory cams. I've had engines as low as 110mm, with the cam timing spot on.
Secondly, there are cams that were incorrectly indexed when they were ground...and the lobe location is not correct. Everything seems correct, until the cam timing is actually measured.
The camshaft specifications are clearly stated in the Workshop Manual....with exact opening and closing events at a universal (German universal) 1mm of travel.
The ONLY way to do this job is to buy a degree wheel (or one of my front dampers that has degrees marked on it), figure out exactly where TDC is, and "degree in" the camshafts. Compare what your results are to what the cam timing should be....correct as required
11-28-2016, 08:48 PM
#25
Rennlist Member
Way back in the misty dim I retimed my 1978 Honda 750 that way.
Used an aluminum rod bent with a notch cut in it to catch the edge of the cylinder. I placed the rod in the #1 cylinder placed a degree wheel on the crank.
I spun the crank one way until it stopped and wrote down the degree. Then I spun the crank the other way and wrote down the degree.
Top determine TDC I divided the number of degrees different by half, add it back to one of the findings and that number was true TDC. Used a modified camshaft gear to dial it in.
The gain in performance was impressive. It was known that Honda did not dial in the cams - after all we are talking about an assembly line.
11-28-2016, 09:13 PM
#26
Captain Obvious
Super User
Super User
That brings back memories...
Way back in the misty dim I retimed my 1978 Honda 750 that way.
Used an aluminum rod bent with a notch cut in it to catch the edge of the cylinder. I placed the rod in the #1 cylinder placed a degree wheel on the crank.
I spun the crank one way until it stopped and wrote down the degree. Then I spun the crank the other way and wrote down the degree.
Top determine TDC I divided the number of degrees different by half, add it back to one of the findings and that number was true TDC. Used a modified camshaft gear to dial it in.
The gain in performance was impressive. It was known that Honda did not dial in the cams - after all we are talking about an assembly line.
Way back in the misty dim I retimed my 1978 Honda 750 that way.
Used an aluminum rod bent with a notch cut in it to catch the edge of the cylinder. I placed the rod in the #1 cylinder placed a degree wheel on the crank.
I spun the crank one way until it stopped and wrote down the degree. Then I spun the crank the other way and wrote down the degree.
Top determine TDC I divided the number of degrees different by half, add it back to one of the findings and that number was true TDC. Used a modified camshaft gear to dial it in.
The gain in performance was impressive. It was known that Honda did not dial in the cams - after all we are talking about an assembly line.