| Author |
Message |
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
 Posted: Tue May 14, 2013 7:18 pm Post subject: Indexing camshaft in the case |
 |
|
I am wondering if there is some way to check the indexing of the camshaft without cracking the case.
I am cleaning and rebuilding my engine as much as I can afford right now, which means I've cleaned up the heads and cylinders and pistons, and I am about to reinstall them.
I was fiddling around trying to get to know my engine's guts a little better, when I was trying to re-install my distributor using the cylinder #1 TDC mark on the distributor housing. So as I was rotating my crank (pistons and cylinders off), I noticed that at TDC for cylinder #1 the cam lobe is not in the optimum position for pushing against the lifter and raising the valve (Intake, I think). I need to rotate it a little more for the full height of the lobe to push against the lifter, and at that position the piston would no longer be at the top of the cylinder.
Is this normal, or is my camshaft not indexed correctly?
It would not surprise me if it was not indexed correctly. The shop who did my last rebuild in 2006 really screwed-up a lot of stuff. I am trying to correct as much as I can now. But I don't want to crack the case right now. I want to get it rolling!!
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
 |
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
| Posted: Tue May 14, 2013 7:54 pm Post subject: |
|
|
Depending on your cam the valves may open and close at some point that isn't all that close to TDC or BDC.
If your cam gear were off by a tooth your engine would run horribly. |
|
| Back to top |
|
|
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Tue May 14, 2013 7:55 pm Post subject: |
|
|
Doesn't sound odd to me, just like spark timing valves need to start opening or closing ahead of the actual event due to inertia in the charge or spent gasses. If you really want to know find someone with a professional quality bore scope or pull the oil pump and peek with a mirror.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:10 pm Post subject: |
|
|
THanks guy!
Also, the #1 piston is, of course, at its highest point twice in the revolution of the cam. Is the way to determine which of these piston high points is TDC when the cam lobe is closest to the lifter?
when the piston is again at its height (180 from TDC, I believe), the lobe is on the opposite side.
Distributor question: indexing the TDC point on my distributor and aligning it with cyl.#1 TDC puts the distributor in a position that the vacuum advance thing on the side of the distributor is down by the oil cooler and I think it will be a problem when I start putting the engine tin back on. (I'll try to snap a pic to show its placement...)
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:16 pm Post subject: |
|
|
vacuum advance placement on the distributor: clearance problems?
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
| Posted: Tue May 14, 2013 8:18 pm Post subject: |
|
|
At TDC compression for the #1 cylinder the valves and rockers will not move as you rock the engine back and forth to 90° either side of the timing mark.
How was your distributor aligned before you removed it? If you haven't mess with the drive it should go back into the same orientation. |
|
| Back to top |
|
|
musktchup
Samba Member
Joined: November 30, 2004
Posts: 207
Location: Wilm. NC
|
| Posted: Tue May 14, 2013 8:19 pm Post subject: |
|
|
you are off 180 degrees.
intake and exhaust should be fully closed at TDC no matter what cam you are running. |
|
| Back to top |
|
|
busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
|
| Posted: Tue May 14, 2013 8:19 pm Post subject: |
|
|
| BusBerd wrote: |
| clearance problems? |
Yes, swap it 180 degrees.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:23 pm Post subject: |
|
|
Interesting: here is a pic of the distributor placement before I took the engine out last fall. It looks to be a complete 180 from TDC indexing point!
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:25 pm Post subject: |
|
|
| Wildthings wrote: |
At TDC compression for the #1 cylinder the valves and rockers will not move as you rock the engine back and forth to 90° either side of the timing mark.
How was your distributor aligned before you removed it? If you haven't mess with the drive it should go back into the same orientation. |
oh, ok.
phew.
thanks!!
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
| Posted: Tue May 14, 2013 8:27 pm Post subject: |
|
|
Unless you have split the case or messed with the drive you most likely have your engine sitting at TDC compression for #3 and not #1. If you have had the drive cog off the bottom of the dizzy shaft, you may have installed that 180° off as well.
You wires look to be on in the wrong position in your early photo, which could be the problem as well. |
|
| Back to top |
|
|
musktchup
Samba Member
Joined: November 30, 2004
Posts: 207
Location: Wilm. NC
|
| Posted: Tue May 14, 2013 8:27 pm Post subject: |
|
|
| you had it at tdc for #3. Glad you got it straighten out. |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:28 pm Post subject: |
|
|
and for my 700th post. I'll just say "thank you thesamba.com!" 
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
BusBerd
Samba Member
Joined: November 19, 2005
Posts: 834
Location: Minneapolis, MN
|
| Posted: Tue May 14, 2013 8:37 pm Post subject: |
|
|
| Wildthings wrote: |
| Unless you have split the case or messed with the drive you most likely have your engine sitting at TDC compression for #3 and not #1. If you have had the drive cog off the bottom of the dizzy shaft, you may have installed that 180° off as well. |
I assume you are talking about the blurry photo that I tried to take just now and not the clear photo that I took last fall. Then yes, I understand. I thought TDC would be when the cam lobe was pushing against the lifter, but now that I think about it, of course it wouldn't be. So right now (tonight) my distributor is sitting with TDC on #3 not #1. I'll just have to spin the distributor housing around to match the photo I took in the fall and match up TDC of #1 with the little mark on the distributor housing.
| Wildthings wrote: |
| You wires look to be on in the wrong position in your early photo, which could be the problem as well. |
you mean the spark plug wires in the clear photo from last fall?? how so? 1,4,3,2, I think, right?
| musktchup wrote: |
| you had it at tdc for #3. Glad you got it straighten out. |
yes! much better clearance.
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission |
|
| Back to top |
|
|
SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
|
| Posted: Tue May 14, 2013 10:51 pm Post subject: |
|
|
You probably don't want something this detailed but you can get very precise on TDC if you want to. On a T4 it should be done with the heads off but on a T1 it can be done with the heads on because the plug angles are so different.
| SGKent wrote: |
Bus type 4 motors are different than type 1 motors in that we rely on a bolt on timing scale. Often the timing scale is broken or bent. If that scale is wrong, your timing will be too and the results of setting the timing wrong on a bus type 4 engine can be disasterous because we carry weight and wind resistance that other VW's don't encounter. Additionally we are geared different and the overall affect is to create greater heat on a bus engine than any other VW. You need to know where TDC is on a bus type 4 engine, especially when you have just spent a ton of money rebuilding it as compared to what a stock Bug, Split or T1 bus owner might spend.
This thread is for anyone wondering how to find exactly where TDC is on a bay bus type 4 engine when assembling it or when the heads are off. You can then compare your TDC mark to the bolt on scale because if the timing scale is off by just a few degrees, your engine timing will be too.
Bolt the flywheel on. Bolt the cylinders down firmly so they can't move. Set your dial indicator up in some fashion where it is secure. Run the #1 piston to as close to TDC as you can and zero the indicator.
Turn the crankshaft until the indicator reads .020" of fall. You can use .050" if you prefer. I use .020".
Lightly mark the flywheel with a fine line at the case split. I use a sharpie and a scribe.
Run the flywheel in the oppisite direction until it reads .020" fall (or whatever number you used in the last step. Scribe a line.
Measure between the two and divide by 2. Make a mark at that distance. It will be TDC. I usually then run it up to .050" and make a second set of marks. They should appear equal distance from the TDC line you drew. When the engine is assembled, you can place the flywheel on this line and compare it to the bolt on scale.
I might add, if you measure the circumference of the flywheel accurately and divide by 360 it will give you the measurement per degree. You can then multiple the per degree number X 7.5 and that will give you a distance to 7.5 degrees where you can draw a second mark to static time it while you are assembling the motor. These lines will not be visible once the engine is in the car, and they are for reference only when assembling the engine. |
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
|
| Back to top |
|
|
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
|
| Posted: Wed May 15, 2013 5:41 am Post subject: |
|
|
| BusBerd wrote: |
| Wildthings wrote: |
| You wires look to be on in the wrong position in your early photo, which could be the problem as well. |
you mean the spark plug wires in the clear photo from last fall?? how so? 1,4,3,2, I think, right? |
The wire order is right but the clocking of the wires is wrong by the book, which would indicate that your distributor drive or drive cog is also in wrong. It will run fine this way just put the wires back as they are in the photo, this is a case where two wrongs make a right. |
|
| Back to top |
|
|
nathansnathan
Samba Member
Joined: April 14, 2008
Posts: 1671
|
| Posted: Wed May 15, 2013 6:12 am Post subject: |
|
|
This may not actually help,  but here is the webcam article on how to degree a cam.
http://www.webcamshafts.com/index_blank.html?pages/degreeing.html
You can do it with the motor in the car. You need a dial indicator and base. It helps to have a metric magnetic base - you can unscrew the the magnetic base and the pole has an 8mm thread so you can screw it right onto the motor. You measure at the valve spring retainer as valve lift, not cam lift, is what cam manufacturers will give. When I did this I taped a printout of a degree wheel to my fan pulley.
It is a little tricky as the measurements are actually something like when will it open when the valve lash is at .050" - so if you set them at zero lash it should reach .050" at the indicated degree. Just about any type 4 bus would have the djet cam even carb'd buses, I think. So the numbers should be as follows for a stock cam
IO: 12 BTDC
IC: 42 ABDC
EO: 43 BBDC
EC: 4 ATDC |
|
| Back to top |
|
|
SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
|
| Posted: Wed May 15, 2013 8:12 am Post subject: |
|
|
| nathansnathan wrote: |
This may not actually help, but here is the webcam article on how to degree a cam.
http://www.webcamshafts.com/index_blank.html?pages/degreeing.html
You can do it with the motor in the car. You need a dial indicator and base. It helps to have a metric magnetic base - you can unscrew the the magnetic base and the pole has an 8mm thread so you can screw it right onto the motor. You measure at the valve spring retainer as valve lift, not cam lift, is what cam manufacturers will give. When I did this I taped a printout of a degree wheel to my fan pulley.
It is a little tricky as the measurements are actually something like when will it open when the valve lash is at .050" - so if you set them at zero lash it should reach .050" at the indicated degree. Just about any type 4 bus would have the djet cam even carb'd buses, I think. So the numbers should be as follows for a stock cam
IO: 12 BTDC
IC: 42 ABDC
EO: 43 BBDC
EC: 4 ATDC |
hi Nathan - the valve lift can be measured on any of the parts that move if all one is doing is the timing. what one is looking for is somewhere between .020 and .050 lift just to make it the same on all the cylinders. When Steve at Webcam measures a cam, he has a special very expensive cambuilder's tool that rides on the lobes. He degreed a cam for me a few years ago and literally his machine reads down to fractions of a degree. In general AC VW camshaft timing is not adjustable as easy as some other cars. To make an adjustment one must split the case. So what you get in a VW is generally what you get. However true TDC is good to know on a T4 engine so one can compare the timing scale to the actual TDC. My scale was off maybe three or four degrees. Right now my TDC on the scale is exactly TDC. Engine timing isn't critical on most engines within 2 or 3 degrees however on the bus I can see the difference in head temps between 28 degrees BTDC and 30 degrees BTDC.
Below is an example of a belt driven set of adjustable timing gears. They are slotted and can be locked to give you the exact advance or retard that you want on the camshaft. T1 adjustable gears exist that use an eccentric to advance or retard the bolt holes which changes the camshaft. FWIW, when I built my T4, I degreed the webcam that Steve and his staff at Webcam sold me and it was exactly on their specs. Not a degree off. That is impressive. The really good thing about the OP here in this thread is that he is trying to do precise work. So are you.That becomes so important over the long run with any mechanical work. It literally becomes the difference between a mechanic -whether hobby or pro - who takes the time to get it right and understand why it is right. When people develop the skills of doing it right they cringe when the see someone tossing together something substandard.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
|
| Back to top |
|
|
nathansnathan
Samba Member
Joined: April 14, 2008
Posts: 1671
|
| Posted: Wed May 15, 2013 9:00 am Post subject: |
|
|
| SGKent wrote: |
hi Nathan - the valve lift can be measured on any of the parts that move if all one is doing is the timing. what one is looking for is somewhere between .020 and .050 lift just to make it the same on all the cylinders. When Steve at Webcam measures a cam, he has a special very expensive cambuilder's tool that rides on the lobes. He degreed a cam for me a few years ago and literally his machine reads down to fractions of a degree. |
The .050" thing is a standard that is often used. There is actually something different about how vw lists the figures, but I forget now. It should be, like you say, about the same, just a way of standardizing it.
If you try measuring anywhere on the rocker, you will find that the surface you are measuring from will start angling down with the arc of its movement, throwing off your reading. Also, any part of the rocker will have moved off the axis of the indicator, that axis being lined up with the valve stem. You will find the spring retainer is the only place to take the reading.
The machine Web Cam has is called a Cam Doctor. I am thinking of going up there, they said they would put some stock cams that I want to figure out on their machine. -I'd really like to compare the figures between their 'stock' cam and a real stock cam, or several actually
| SGKent wrote: |
In general AC VW camshaft timing is not adjustable as easy as some other cars. To make an adjustment one must split the case. So what you get in a VW is generally what you get.
|
Having once installed the cam a few teeth off (don't ask me how that happened I don't really know  ), I have learned this the hard way. I could have indexed the cam then to figure out what I had done. I took it to a shop, and they confirmed it through process of elimination, got fuel, spark, spark timing, but won't start without the cam closing the valves at the right time. They told me they'd fix it for $7000. It was real painful to have to split that case again, but not $7000 painful |
|
| Back to top |
|
|
SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
|
| Posted: Wed May 15, 2013 9:20 am Post subject: |
|
|
| nathansnathan wrote: |
| SGKent wrote: |
hi Nathan - the valve lift can be measured on any of the parts that move if all one is doing is the timing. what one is looking for is somewhere between .020 and .050 lift just to make it the same on all the cylinders. When Steve at Webcam measures a cam, he has a special very expensive cambuilder's tool that rides on the lobes. He degreed a cam for me a few years ago and literally his machine reads down to fractions of a degree. |
The .050" thing is a standard that is often used. There is actually something different about how vw lists the figures, but I forget now. It should be, like you say, about the same, just a way of standardizing it.
If you try measuring anywhere on the rocker, you will find that the surface you are measuring from will start angling down with the arc of its movement, throwing off your reading. Also, any part of the rocker will have moved off the axis of the indicator, that axis being lined up with the valve stem. You will find the spring retainer is the only place to take the reading.
The machine Web Cam has is called a Cam Doctor. I am thinking of going up there, they said they would put some stock cams that I want to figure out on their machine. -I'd really like to compare the figures between their 'stock' cam and a real stock cam, or several actually
| SGKent wrote: |
In general AC VW camshaft timing is not adjustable as easy as some other cars. To make an adjustment one must split the case. So what you get in a VW is generally what you get.
|
Having once installed the cam a few teeth off (don't ask me how that happened I don't really know ), I have learned this the hard way. I could have indexed the cam then to figure out what I had done. I took it to a shop, and they confirmed it through process of elimination, got fuel, spark, spark timing, but won't start without the cam closing the valves at the right time. They told me they'd fix it for $7000. It was real painful to have to split that case again, but not $7000 painful |
The stock web142 grind for a T4 is based on the GA camshaft used in the 2L GA porsche 914. It is more radical than the stock bus cams. I offered them six to eight cam cores free and they just put them in the scrap heap. Once the gears are off they don't reuse a cam. It is easier to grind a new one from a blank.
I thought the Cam Doctor was computerized. This is a non-computer device made probably in the 60's.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
|
| Back to top |
|
|
|
