z99ls1

iTrader: (12)

Ok so on the GM procedure it looks like they say you are on #1 tdc on compression stroke when your camshaft dot is at the 12-oclock position and the crankshaft dot is at the 12-oclock position so you can adjust both valves at that time. Or are you saposed to have the camshaft dot at 6-oclock and the crank dot at 12-oclock?

z99ls1

iTrader: (12)

vettenuts

iTrader: (4)

Put a pushrod in the intake of cylinder #1 and keep a little finger pressure on it. Rotate the motor until the pushrod goes up and then down (valve closes). Then rotate until the dots align, which should be approximately 1/3 turn from closure. You have to keep a finger on the pushrod to ensure the lifter doesn't hang in the lifter tray.

z99ls1

iTrader: (12)

thanks I was planning on doing that, but do you know when #1 tdc is? I keep seeing people say it differently. Is it when the camshaft dot is at 6 and the crank is at 12 or when they are both at 12?

Pocket

iTrader: (22)

Using the stock rockers it makes no difference what the engine position is

TQ to 24lb/ft, rotate crank 180* and test TQ again, button it up and call it a day

flintwrench69

iTrader: (11)

Yes camshaft dot at 6 & crankshaft dot at 12, or dot to dot lined up with each other is #1 tdc. With them both in the 12 o clock position the #6 cyl is at tdc.

z99ls1

iTrader: (12)

Sorry that is false.

z99ls1

iTrader: (12)

Lol your camshaft at 6 and crank at 12 is the same as them being dot to dot lined up. Do you mean with them both cosest to eachother #6 is on tdc or are you mean when they are 12 and 12 (furthest apart) they are on #6 tdc?

flintwrench69

iTrader: (11)

yea

yea

z99ls1

iTrader: (12)

LOL yea what. I asked 2 different questions. Now im more confused more than ever. Shouldn't be this hard. I'll just find out when I get into the dam motor lol

01ssreda4

iTrader: (96)

Wow

OP, TDC has nothing to do with the cam. NOTHING. Only the crank position matters. If it is at 12, you are at #1 TDC. Period.

z99ls1

iTrader: (12)

Wtf are you talking about lol? Tdc has nothing to do with the cam lol? It really does. When your on compression tdc for a cylinder both the lifters on that cylinder are on base lobe and can be adjusted. Your the one not getting it. Yes number 12 on the crank you are at tdc. DUH! The camshaft turns at half the speed of your crank. You can turn the crank over twice and the camshaft will be in a different postion each time. Just because your on tdc for a cylinder does not mean you can adjust the valves on that cylinder. Your cam also has to be in the right spot so you "set" the valves at the right spot. My question is does the camshaft dot need to be at 6 oclock or 12 oclock. Yes I know 12 oclock always on the crank dot. It takes 720 degrees to complete you four strokes. Im needing to know when #1 will be on the compression stroke at tdc! No need to answer anymore though. This post is useless unless I get somone in here that knows what im saying. It will be easy to figure out where it needs to be when I tear it down and I can watch the valves move. WOW

01ssreda4

iTrader: (96)

So you can't find TDC with no cam in the engine?......Thought so.

flintwrench69

iTrader: (11)

Sounds like the OP is trying to figure out how to get #1 tdc compression.

Both of the questions you asked are correct.
No it shouldnt be nearly as hard to understand as youre making it seem. What does your service manual say about replacing a timing chain? Have you figured out why the marks are on the timing gears?
Wow you havent even got it apart yet? Better get movin then.

MrEddie

If you have #1 spark plug removed, then put your finger over the hole and rotate engine until you feel pressure (both valves closed). Then put a straw in the hole and keep going until it reaches its max height = tdc.

01ssreda4

iTrader: (96)

BTW, valves on these motors don't need to be "set" or whatever it is you are trying to do. You have a service manual that is telling you which one of the 2 TDCs you need and you think you will get better answers here then a service manual??? Service manuals are gonna be correct 99.9% of the time. With some of the threads I have seen lately, you might get like 50-60% correct answers around here. Maybe less.

nocooler

iTrader: (5)

Find TDC - doesn't matter if it's intake or exhaust stroke.

Push down on the pushrods - if they go down then torque the rocker, spin the engine 180* and tight the other half of the rockers.

Not rocket science - you just want the lifter on the cam base circle before torquing the rocker.

farmington

iTrader: (14)

TDC with #1 firing is both dots at 12. Period.

flintwrench69

iTrader: (11)

Depends on what youre trying to accomplish. If checking for proper pushrod length or degreeing a cam then it matters what TDC stroke the crank is on in relation to the cam lobes. If just reinstalling some stock rocker arms then it doesnt matter at all. That info that the OP posted is straight from the GM SI but their procedure is unnecessary & their pic of the timing chain is actually #6 cyl TDC compression stroke.

ZeeOSix

So you're saying that step 6 in the Service Manual page in Post #2 is wrong? It's saying that the dots on both the cam and crank sprockets should be at 12 o'clock when Cyl #1 is on compression stroke TDC.