TDC Again. I can't figure it out.
01-20-10, 08:13 PM
#1
TDC Again. I can't figure it out.
As far as I know you can take the pulley boss keyway and point 90 degrees left and this will be TDC and that I should be able to pick the pulley . (IE towards the intake and exhaust ports.)
Now here is the pictures I took with the keyway 90 degrees and what the pointer on the oil cover should point to TDC.
First picture is sitting on a blown motor. Pen shows Leading 5 degress yellow mark and you can see the bottom pulley yellow mark. This is with the key way 90 degrees to the left. (Facing the intake and exhaust ports)
Second picture you can see it on a rebuilt engine with the keyway pointing 90 degrees to the left.
Third picture is just another pulley boss assemble sitting on the keyway for comparision. (This pulley was in one piece)
I thought that putting the keyway at 90 degrees I should see the yellow mark 5 degrees on the right of the timing pin.
How can I make something so simple so complicated......
some ref http://www.teamfc3s.org/info/articles/demystifying.html
Now here is the pictures I took with the keyway 90 degrees and what the pointer on the oil cover should point to TDC.
First picture is sitting on a blown motor. Pen shows Leading 5 degress yellow mark and you can see the bottom pulley yellow mark. This is with the key way 90 degrees to the left. (Facing the intake and exhaust ports)
Second picture you can see it on a rebuilt engine with the keyway pointing 90 degrees to the left.
Third picture is just another pulley boss assemble sitting on the keyway for comparision. (This pulley was in one piece)
I thought that putting the keyway at 90 degrees I should see the yellow mark 5 degrees on the right of the timing pin.
How can I make something so simple so complicated......
some ref http://www.teamfc3s.org/info/articles/demystifying.html
01-21-10, 06:43 AM
#2
I may be missing something here, but this should be impossible to get wrong. The timing chain on these engines is put on with the keyway as well, so that can't be out. The front pulley goes on only one way due to the oblonged holes on the hub.
Now heres speculation, isn't the timing slightly different on a s4 to a s5 engine? I just remember hearing that?
Now heres speculation, isn't the timing slightly different on a s4 to a s5 engine? I just remember hearing that?
01-21-10, 08:12 AM
#3
Not sure what you're dealing with but...
- When the engine is at true TDC the timing marks should NOT align with the pin. The red timing mark is at 5* ATDC so the crank will need to be at 5* ATDC for the mark to align with the pin. Just using your eyeball you're going to have a pretty tough time seeing 5*.
- Hubs and pulley are drilled and tapped for the bolts as a set. If you swap pulleys between different hubs you're probably going to have a timing issue.
- The best way to check a pulley is to have a known good, single piece aftermarket pulley like an RB for a reference. Tear down your blown engine and use a dial indicator to find true TDC. I used a scrap plate to find a reference point to mount the dial indicator. If the indicator isn't in the right spot you're not going to find true TDC. Check the aftermarket pulley for accuracy (I've found some to be innaccurate) and then keep that pulley as a reference for future use. If you don't want to spec the money you can also check a stock pulley in the same way. Keep in mind when you're marking this reference pulley that if you place the crank at TDC and make a mark on the pulley that aligns with the indicator pin on the front cover that mark represents TDC and not the factory mark of 5* ATDC (related to point #1 above).
- When the engine is at true TDC the timing marks should NOT align with the pin. The red timing mark is at 5* ATDC so the crank will need to be at 5* ATDC for the mark to align with the pin. Just using your eyeball you're going to have a pretty tough time seeing 5*.
- Hubs and pulley are drilled and tapped for the bolts as a set. If you swap pulleys between different hubs you're probably going to have a timing issue.
- The best way to check a pulley is to have a known good, single piece aftermarket pulley like an RB for a reference. Tear down your blown engine and use a dial indicator to find true TDC. I used a scrap plate to find a reference point to mount the dial indicator. If the indicator isn't in the right spot you're not going to find true TDC. Check the aftermarket pulley for accuracy (I've found some to be innaccurate) and then keep that pulley as a reference for future use. If you don't want to spec the money you can also check a stock pulley in the same way. Keep in mind when you're marking this reference pulley that if you place the crank at TDC and make a mark on the pulley that aligns with the indicator pin on the front cover that mark represents TDC and not the factory mark of 5* ATDC (related to point #1 above).
Last edited by C. Ludwig; 01-21-10 at 08:18 AM.
01-21-10, 08:45 AM
#4
Also Ian, something I've found helps. When you're using the keyway @ 9 oclock method, take a spare key and stand it in the keyway perpendicular to the shaft Ie. like the hands of a clock.
It can LOOK to be @ 9 oclock, but may actually be off a bit. having a pointer on it makes aligning it much easier. with the keyway standing on the shaft you can measure between each end of the pointer and the flange for the oil pan to make sure its exactly @ 9 oclock.
check your email in an hour too buddy
It can LOOK to be @ 9 oclock, but may actually be off a bit. having a pointer on it makes aligning it much easier. with the keyway standing on the shaft you can measure between each end of the pointer and the flange for the oil pan to make sure its exactly @ 9 oclock.
check your email in an hour too buddy
01-21-10, 04:58 PM
#7
I may be missing something here, but this should be impossible to get wrong. The timing chain on these engines is put on with the keyway as well, so that can't be out. The front pulley goes on only one way due to the oblonged holes on the hub.
Now heres speculation, isn't the timing slightly different on a s4 to a s5 engine? I just remember hearing that?
Now heres speculation, isn't the timing slightly different on a s4 to a s5 engine? I just remember hearing that?
I printed a timing wheel and will just rest the timing wheel on the engine with the keyway at 90 degrees. Then I will rotate the engine 5 degrees clockwise and just match up the marks. Worst case I will just get a set.
I have the racing beat pulley installed on my race engine. This was done professionally. I also have my running engine from my 10th ae sitting beside the S5 so I can use that as a comparision.
I think I just have a mixture of s5 and s4 pulleys and bosses.....
Thanks for your help guys.
O and classicauto there was nothing in my email account? Work or home.....
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