Finding Tdc
04-11-2005, 11:59 PM
#1
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Thread Starter
Join Date: Apr 2003
Posts: 32
Searching turned up this: http://www.teamfc3s.org/info/article...fying.html#TDC for finding TDC
so I gave it a try and my "TDC" came out about 20 deg off (retarded) from
what it should have been, so... is the procedure correct? has anybody tried the above and gotten correct results using it?
-Henrik
so I gave it a try and my "TDC" came out about 20 deg off (retarded) from
what it should have been, so... is the procedure correct? has anybody tried the above and gotten correct results using it?
-Henrik
04-12-2005, 01:28 AM
#2
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Join Date: Oct 2002
Location: Phoenix, AZ
Posts: 296
Finding true TDC is a toughy because are not really any good timing markings boss bolt or crank pulley. So even if you have the red and yelllow marks on the pulley( most of them just go away with age) its the timing for the engine at ide at different degrees of timing.
So you its still super critical that you need it dead on ( for some type of computor magnetic pick up system) you will have to remove the main boos retainer (bolt) fab up a degress wheel so you can use the e-shaft fron front key as a guide. you should get it right one with no problem.
but removing of the boss pulley does come at some risk as it may let the thrust washer and bearings behind the bearing plate come loose and slip off the e-shaft. so when you retighen the pulley you might crunch the bearing and the thrust washer and not even know it.
but if it not that critical just move the apex seal mid way between the tailing and leading spark plug on one rotor and the other rotor will be close to TDC. I think this method you can get within 10-4 degress of the true TDC.
good luck
So you its still super critical that you need it dead on ( for some type of computor magnetic pick up system) you will have to remove the main boos retainer (bolt) fab up a degress wheel so you can use the e-shaft fron front key as a guide. you should get it right one with no problem.
but removing of the boss pulley does come at some risk as it may let the thrust washer and bearings behind the bearing plate come loose and slip off the e-shaft. so when you retighen the pulley you might crunch the bearing and the thrust washer and not even know it.
but if it not that critical just move the apex seal mid way between the tailing and leading spark plug on one rotor and the other rotor will be close to TDC. I think this method you can get within 10-4 degress of the true TDC.
good luck
04-12-2005, 10:29 PM
#3
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Join Date: Apr 2003
Posts: 32
See that's the thing, I am looking for true TDC (I'm doing some ECU mods)
which is what the article in the link describes finding (using the apex seal half
way between the lead/trail spark plug holes method). My yellow/red paint
marks are still quite visible so no problems there but I was expecting it to
be much closer than the 20 deg off that I found, I mean 20 deg is huge!
Is it possible that the rotors are a tooth off? or do the mechanics of the
motor prevent this from even being possible?
-Henrik
which is what the article in the link describes finding (using the apex seal half
way between the lead/trail spark plug holes method). My yellow/red paint
marks are still quite visible so no problems there but I was expecting it to
be much closer than the 20 deg off that I found, I mean 20 deg is huge!
Is it possible that the rotors are a tooth off? or do the mechanics of the
motor prevent this from even being possible?
-Henrik
04-12-2005, 10:56 PM
#4
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Join Date: May 2002
Location: California
Posts: 22,465
its not possible for the engine to be off a tooth, theres no way to assemble it like that.
theres a picture floating around here, the keyway on the front of the eshaft points to 9 o clock @ tdc, if you're looking at the front of the motor
theres a picture floating around here, the keyway on the front of the eshaft points to 9 o clock @ tdc, if you're looking at the front of the motor
04-13-2005, 10:47 AM
#6
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Join Date: Aug 2004
Location: San Diego
Posts: 186
[quote name='Henrik' date='Apr 12 2005, 11:14 PM']Yeah that's what I was thinking but since I have not had one apart (at
least yet!) had to ask... popping the front hub off isn't easy for me -
no air tools
so I was hoping for an easier way...
-Henrik
[/quote]
Don't need to pull the front hub off. If your motor is stock and has never been out spin the motor until the the yellow marker lines up with the pointer, this should be the first mark and is leading, it is 5 degrees ATDC. Unbolt the pulley it should be 4 10mm bolts it will come off the hub. Now get a cloth measuring tape like the ones you find in a sewing kit or a steel one that you don't mind bending. Mark 5mm to the right of the leading yellow mark, that would be clockwise, that would put you dead on zero. How do you say well the stock pulley happens to be 360mm around so each 1mm equals 1degree so you move from the 5 degree mark 5mm and you are at 0 degrees TDC. Hope this helps you out.
least yet!) had to ask... popping the front hub off isn't easy for me -
no air tools
so I was hoping for an easier way...-Henrik
[snapback]699088[/snapback]
[/quote]
Don't need to pull the front hub off. If your motor is stock and has never been out spin the motor until the the yellow marker lines up with the pointer, this should be the first mark and is leading, it is 5 degrees ATDC. Unbolt the pulley it should be 4 10mm bolts it will come off the hub. Now get a cloth measuring tape like the ones you find in a sewing kit or a steel one that you don't mind bending. Mark 5mm to the right of the leading yellow mark, that would be clockwise, that would put you dead on zero. How do you say well the stock pulley happens to be 360mm around so each 1mm equals 1degree so you move from the 5 degree mark 5mm and you are at 0 degrees TDC. Hope this helps you out.
04-13-2005, 10:48 PM
#7
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Join Date: Apr 2003
Posts: 32
Yep the logic is good. Motor has been out/apart once (previous owner had
the injectors serviced at a dealer and they dropped one of the grommets
into the engine - re&re the engine to get it out...) From looking at the FSM
etc. everything is keyed, but is there anyway it could be assembled wrong
(and hence timing is off)
-Henrik
the injectors serviced at a dealer and they dropped one of the grommets
into the engine - re&re the engine to get it out...) From looking at the FSM
etc. everything is keyed, but is there anyway it could be assembled wrong
(and hence timing is off)
-Henrik
04-14-2005, 10:01 AM
#8
Senior Member
Join Date: Aug 2004
Location: San Diego
Posts: 186
[quote name='Henrik' date='Apr 13 2005, 08:48 PM']Yep the logic is good. Motor has been out/apart once (previous owner had
the injectors serviced at a dealer and they dropped one of the grommets
into the engine - re&re the engine to get it out...) From looking at the FSM
etc. everything is keyed, but is there anyway it could be assembled wrong
(and hence timing is off)
-Henrik
[/quote]
Nope motor can't be assembled wrong it only goes together one way but the pulley could be positioned incorrectly on the hub that can happen.
the injectors serviced at a dealer and they dropped one of the grommets
into the engine - re&re the engine to get it out...) From looking at the FSM
etc. everything is keyed, but is there anyway it could be assembled wrong
(and hence timing is off)
-Henrik
[snapback]699522[/snapback]
[/quote]
Nope motor can't be assembled wrong it only goes together one way but the pulley could be positioned incorrectly on the hub that can happen.
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