View Full Version : Tdc??????
SRpetey
08-20-2009, 08:11 PM
could your cam dowel be at 10 and 12 and your crank pully at the second mark from the left (TDC) and still not at TDC?
zylvia213
08-20-2009, 10:40 PM
what are you doing that you have to find TDC?
SRpetey
08-20-2009, 11:51 PM
I'm installing cams. Its just that I remember reading somewhere that having the cam dowel at 10 n 12 and the crank pully t the second mark from the left doesn't mean its at TDC. Is that true?
cotbu
08-21-2009, 01:13 AM
TDC refers to the pistons' position in it's traveling range. So measure that! The easiest way is to stick a long screwdriver, dowel or something in the #1 spark plug hole....! As you turn the crank pulley to align the mark with 0 deg too match the cams at 10 n 12 look at the screwdriver it should stop moving up! Compression stroke!
OH yeah your question!
I'm installing cams. Its just that I remember reading somewhere that having the cam dowel at 10 n 12 and the crank pully t the second mark from the left doesn't mean its at TDC. Is that true?
Yes!
SRpetey
08-21-2009, 02:25 PM
okey ia have another question. My time is at 15* at 1100rpm but the rpm sometims drops to 800rpm and the timing drops to 5*. Is that normal? Does my idle have to be at 800rmp and timing at 15*? if so how do i make my idle be at 800rpm and timing at 15* at the same time.
cotbu
08-21-2009, 03:36 PM
I know what method you're using and it's a work-around method. Use the standard method of putting the car in timing mode, then set the idle rpm to 750 +/- 50rpm. then check timing with a light adjust to 15deg lock it down and in. plug the TPS back in and you should be @800-/+ 50rpm with timing at a solid 15degs. if your idle fluctuates (vacuum change) then the timing will change. it's normal. The work-around works it's just not ideal for setting idle below 900rpm.
steve shadows
08-21-2009, 04:44 PM
okey ia have another question. My time is at 15* at 1100rpm but the rpm sometims drops to 800rpm and the timing drops to 5*. Is that normal? Does my idle have to be at 800rmp and timing at 15*? if so how do i make my idle be at 800rpm and timing at 15* at the same time.
Remove your TPS plug, then check your Timing by using the diagnostic loop at the back of the wiring harness.
Thankyou
ps. sorry just saw above post, what he menitons is also true.
You need to set Comp into timing mode by unplugging the TPS
Veracity84
08-21-2009, 04:52 PM
Ideally your timing is on 20* degrees BTDC +/-2. You need to get it idling at 750 rpm +/- as indicated in the other gentlemen's post.
Now how can you get the idle down to 750rpm?
1. If you never cleaned the Idle Air Control Valve (IACV) unit, then remove it from the back of the intake manifold and clean it. Take carb cleaner and totally disassemble it, remove the springs, idle adjust screw, etc, and clean them all.
Put it back it and set the idle adjust screw fully out, so that if the car idles high, you can tighten the screw and lower the idle. If this doesn't work, then you have too much air and or other components are not working properly.
Your cams must line up to the marks on the chain.
Are you installing Aftermarket cams? If so, you will need to read about the correct timing settings.
Veracity84
08-21-2009, 04:53 PM
Are we talking about SR? RB? SOHC? DOHC?
Something we should know first before giving tech tips.~
SRpetey
08-21-2009, 08:08 PM
its an sr and the cams were s3 jwt evrything is lines up too. so for timing mode i just diconect the tps and rev past 3k 3 times then adjust rpm to 750 +- then set timing to 15* then once evrything is set rev to 3k 3 times to lock it in then connect tps back in.
SRpetey
08-26-2009, 11:40 AM
okey I'm having trouble setting my idle and timing. If I get it to idle at 750rpm when I give it some throttle the rpm stops at like 1300rpm. it idles at 1300rpm for a while and then it drops back to 750rpm. and this is with the tps unplug but this also happens when I'm on the road at a stop. what's causing this and do I set the timing to 15* when its at 750rpm?
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