Dans55
Newbie
Posts: 46
Reg: 03-03-22
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09-22-24 06:43 AM - Post#2874075
On my 350 chevy engine I want to make sure I'm on tdc. Intake and distributor and valve covers removed. I have the engine on the compression stroke and the harmonic balancer timing mark is on the 0. Both #1 valves should be closed. My question is should the the two #1 rocker arms be loose as to be able to put a 0.02 feelers guage or just touching the valves. Or 
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bobb
Super Senior Member
Posts: 6790
Loc: paradise
Reg: 09-05-03
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09-22-24 10:22 AM - Post#2874081
In response to Dans55
why is tdc so important?
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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 Shepherd
Valued Contributor
Posts: 3536
Loc: Lake George, NY
Reg: 11-11-15
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09-22-24 10:41 AM - Post#2874082
In response to Dans55
Yes, but make sure the balancer is in good shape, and doesn't look like the outer ring has moved.
Edited by Shepherd on 09-22-24 10:48 AM. Reason for edit: No reason given.
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Dans55
Newbie
Posts: 46
Reg: 03-03-22
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09-22-24 04:12 PM - Post#2874091
In response to bobb
Since the engine is about 55 years old and it looks like the balancer hasn't been changed I want to know if it's defective and giving me the wrong timing mark. That's why I asked about the #1 cylinder valves.
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52_Belair
Senior Member
Posts: 276
Loc: Canby, Oregon
Reg: 03-25-03
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09-22-24 05:07 PM - Post#2874097
In response to Dans55
You're not going to be able to determine exact TDC with the valve adjustment, you need to actually see the piston to tell for sure. Some old timers used to set the valve lash with the engine running so I don't think the exact feel of how much friction on the feeler gauge matters.
Edited by 52_Belair on 09-22-24 05:12 PM. Reason for edit: No reason given.
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Shepherd
Valued Contributor
Posts: 3536
Loc: Lake George, NY
Reg: 11-11-15
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09-22-24 06:57 PM - Post#2874099
In response to Dans55
To find true TDC you can use the piston positive stop method, plenty of Utube videos on the method.
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Don57
"19th Year" Silver Supporting Member
Posts: 1441
Age: 74
Loc: Illinois
Reg: 04-28-00
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09-23-24 01:46 PM - Post#2874121
In response to Dans55
My question is should the the two #1 rocker arms be loose as to be able to put a 0.02 feelers guage or just touching the valves. Or
Unless you have a solid lifter cam, you should have zero clearance when the valves are closed. With hydraulic lifters, you actually should be preloading the lifters about 1/2 to 3/4 of a turn on the rocker adjustment.
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Shepherd
Valued Contributor
Posts: 3536
Loc: Lake George, NY
Reg: 11-11-15
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09-23-24 03:54 PM - Post#2874132
In response to Don57
Don, you are correct here, but it is possible the lifters can collapse some when the engine hasn't been run in a while, thus the .002 clearance.
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bobb
Super Senior Member
Posts: 6790
Loc: paradise
Reg: 09-05-03
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09-25-24 08:28 AM - Post#2874182
In response to Dans55
i just pull a plug bring it up to almost tdc, stick a screwdriver in it and rotate slowly feeling the piston travel. the timing marks are not so important. time it where it runs well.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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Don57
"19th Year" Silver Supporting Member
Posts: 1441
Age: 74
Loc: Illinois
Reg: 04-28-00
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09-25-24 08:33 AM - Post#2874185
In response to Shepherd
"Don, you are correct here, but it is possible the lifters can collapse some when the engine hasn't been run in a while, thus the .002 clearance."
No. Unless the lifter is defective, the spring inside the lifter will keep the pushrod seat up tight against the pushrod and rocker arm. Now if you are rotating the engine and find that clearance, wait a few minutes and it probably won't be there.
Here is a simple method for adjusting .......
Back off the rocker arm adjuster.
Wait a few minutes for the lifter to return to a neutral position.
The spring inside the lifter will move the pushrod seat up against the retaining lock.
Hold the intake pushrod with your fingers while tightening down the rocker arm.
When you just take the up and down movement out of the pushrod, you are at zero lash.
Turn the adjusting nut down 1/2 to 1 full turn from that point. Do not back off the adjusting nut.
Lock The Rocker Arm In Place.
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4dr 57
"11th Year" Silver Supporting Member
Posts: 4856
Loc: Texas Hill Country
Reg: 11-10-04
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09-29-24 04:31 PM - Post#2874297
In response to Dans55
Have you spun it over with the starter to make sure the rocker arms are getting oil? You should be able to loosen the rocker arms .002 to .010 for this if desired without a problem. If your nervous about it, check the ricker arms for looseness..try spinning the pushrod with your fingers as you bump the starter with a remote starter button with the ignition off.
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