Finding TDC Compression stroke
11-25-2011, 11:12 AM
#1
Finding TDC Compression stroke Im trying to Find TDC for cylinder #1 on the compression stroke. I have the heads on timing cover on and the rockers off. I know how to find TDC (i have a piston stop) but i don't know weather i am on the compression stroke or the exhaust stroke. How do i figure out which stroke im on with the timing cover on and the rockers off?
11-25-2011, 11:27 AM
#2
If cam and valve train are in, ( you only mentioned rockers missing, I don't know if your lifters, pushrods and springs are installed) install those two rockers. #1 cyl of course, take out spark plug and put your finger in the spark plug hole. Spin until Air is being forced out. You're on the compression stroke.
Is it a big deal to put the two rockers back on? Question is in a nice tone, because I understand I don't know all the issues on your end.
Is it a big deal to put the two rockers back on? Question is in a nice tone, because I understand I don't know all the issues on your end.
11-25-2011, 11:35 AM
#3
If cam and valve train are in, ( you only mentioned rockers missing, I don't know if your lifters, pushrods and springs are installed) install those two rockers. #1 cyl of course, take out spark plug and put your finger in the spark plug hole. Spin until Air is being forced out. You're on the compression stroke.
Is it a big deal to put the two rockers back on? Question is in a nice tone, because I understand I don't know all the issues on your end.
Is it a big deal to put the two rockers back on? Question is in a nice tone, because I understand I don't know all the issues on your end.
no its no big deal at all to put them on... i was just under the impression in order to properly put the rockers on you have to be on the base circle for that lifter. so if im not on the base circle and just bolt the rockers on wouldn't that mess up my valve events (i.e. a valve hanging open)? I guess i could take off the dual springs and stick on some light weight checker springs to get around this issue, i just wanted to minimize the amount of effort spent. maybe im just thinking to much
11-25-2011, 12:08 PM
#4
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try to put rockers on @ TDC, if the springs start to compress (open the valves) stop tightening the rockers, back them off, and spin the engine to TDC again, this should put you on compression, really the only thing tightening the lifters off of base circle will do is make it difficult or impossible to accurately torque them and you cannot correctly check preload
11-25-2011, 12:25 PM
#5
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If you really want to make sure the lobe you're working on is on the base circle you can always just take a pushrod and push it down onto the lifter and spin the motor over. Once its down as far as you think it will go turn the motor over another half turn to make sure you're completely off the closing ramp just to be safe.
Last edited by JS01; 11-25-2011 at 12:30 PM.
11-25-2011, 01:15 PM
#6
If you really want to make sure the lobe you're working on is on the base circle you can always just take a pushrod and push it down onto the lifter and spin the motor over. Once its down as far as you think it will go turn the motor over another half turn to make sure you're completely off the closing ramp just to be safe.
11-25-2011, 04:04 PM
#7
You don't need to install the rocker arms. Just install the cyl #1 Intake pushrod, and turn the motor over by hand while monitoring the movement of the pushrod. As you turn the engine clockwise, the cyl #1 intake pushrod will move up and then down. After it has moved all the way down (ie, intake valve closed), then the piston is at the bottom of the intake stoke. Turning the crank another 180 deg from there will put you at TDC on the compression stroke.
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11-25-2011, 05:29 PM
#8
Doesn't anybody use toilet paper anymore? Some of the old school stuff still works. It helps to know the basics. Just because you have a scan tool doesn't necessarily mean it's time to throw the old dust covered vacuum gauge your dad bought 40 years ago away just yet. Never forget an engine is just and air pump so positive and negative air pressure is a good thing to be knowledgeable about. It's scary to realize some people get this far into their engines and don't understand the concept of how the 4 stroke cycle works. Good luck man. You're goin to need it.
11-25-2011, 05:53 PM
#9
Doesn't anybody use toilet paper anymore? Some of the old school stuff still works. It helps to know the basics. Just because you have a scan tool doesn't necessarily mean it's time to throw the old dust covered vacuum gauge your dad bought 40 years ago away just yet. Never forget an engine is just and air pump so positive and negative air pressure is a good thing to be knowledgeable about. It's scary to realize some people get this far into their engines and don't understand the concept of how the 4 stroke cycle works. Good luck man. You're goin to need it.
also when did i say anything about a scan tool, your way the **** off topic on that one bubs. keep your negativity to yourself or just dont reply to any of my threads. believe me i wont reply negatively to yours. p.s. thanks to the above posters besides eallanboggs (got it figured out way before you chimed in)
