Adjusting Valves

smithrock

Petty Officer 1st Class
Joined
Jun 11, 2007
Messages
399
'85 Mercruiser V6 4.3l
Anyone know a idiot proof way to adjust the valves or have a link on how to? I would like to do it with the engine off if possible
 

mkast

Lieutenant Commander
Joined
Nov 6, 2002
Messages
1,934
Re: Adjusting Valves

Have you looked in the maintenance manual?
You can find it in the adults only thread at the top of the page.
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
Messages
62,321
Re: Adjusting Valves

If you are using the engine off method. When you tighten down the rocker arms to remove the play in the pushrod. Just roll the lifter back and forth between your fingers. The second it stops turning while you are tightening the lifter. STOP. That is zero lash. It will loosen up but DO NOT tighten anymore to stop the lash. DO it one time and one time only. Then go your 3/4 to 1 full turn on the lifter and call it good for that lifter and move on to the next.
 

505callyourball

Seaman Apprentice
Joined
Jul 7, 2009
Messages
47
Re: Adjusting Valves

Here is a paste from another site. It states one full turn and that I may not agree with, 3/4 may be better. I've used this method before, seems to work fine for me on my race car which is also a chevy product.

Here is the valve adjustment procedure:

Remove rocker arm cover.
Rotate engine until mark on torsional damper is aligned with "0" mark on timing tab fastened to crankcase front cover. To ensure engine is at No. 1 cylinder firing position, place fingers on No. 1 cylinder valves as the mark on damper approaches the "0" mark on timing tab. If valves are not moving, engine is in the No. 1 cylinder firing position. If valves are moving, engine is in the No. 4 cylinder firing position and should be rotated one revolution.
With engine in No. 1 cylinder firing position, adjust the following valves:

Exhaust valves 1, 5 and 6.
Intake valves 1, 2 and 3.
NOTE: Even numbered cylinders are in the left bank and odd numbered cylinders are in the right bank, when viewed from front of the engine.

Back off adjusting nut until lash is felt at pushrod, then tighten nut until all lash is removed. This can be determined by rotating pushrod while turning adjusting nut. When all lash is removed, tighten adjusting nut one full additional turn to center lifter plunger.
Crank engine one full revolution until mark on torsional damper and "0" mark on timing tab are again in alignment. This is the No. 4 cylinder firing position. With engine in this position, adjust the following valves:

Exhaust valves 2, 3 and 4.
Intake valves 4, 5 and 6.
Install valve covers and related components, then start engine and check timing and idle speed.
 

smithrock

Petty Officer 1st Class
Joined
Jun 11, 2007
Messages
399
Re: Adjusting Valves

Ok. thanks guys. I'll give it a go this week.
 

smithrock

Petty Officer 1st Class
Joined
Jun 11, 2007
Messages
399
Re: Adjusting Valves

If you are using the engine off method. When you tighten down the rocker arms to remove the play in the pushrod. Just roll the lifter back and forth between your fingers. The second it stops turning while you are tightening the lifter. STOP. That is zero lash. It will loosen up but DO NOT tighten anymore to stop the lash. DO it one time and one time only. Then go your 3/4 to 1 full turn on the lifter and call it good for that lifter and move on to the next.

Don,
I already have the intake manifold back on, so no chance at getting to the lifters. Can I use your method with just removing play in the pushrods?
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: Adjusting Valves

Don is referring to the push rods that you see under the valve cover.
Intake has nothing to do with it.
 

505callyourball

Seaman Apprentice
Joined
Jul 7, 2009
Messages
47
Re: Adjusting Valves

yep certain order so you're adjusting each valve when it's normally closed
 

smithrock

Petty Officer 1st Class
Joined
Jun 11, 2007
Messages
399
Re: Adjusting Valves

As no one mentioned it, only adjust the valves on an engine that is completely warmed up.

How am I suppose to do that if I had everything apart and the valves aren't adjusted from removing the heads? The last thing I want is to put a rod through a piston or cause damage to something!
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Adjusting Valves

You do not have to warm an engine to adjust the valves statically.
 

smithrock

Petty Officer 1st Class
Joined
Jun 11, 2007
Messages
399
Re: Adjusting Valves

You do not have to warm an engine to adjust the valves statically.

Ok. Should I re-adjust them though after the engine is warm? I hope to get it done this week. Too damn hot out to work in the boat right now!
 

drpboston

Cadet
Joined
Jul 12, 2008
Messages
22
Re: Adjusting Valves

With engine in No. 1 cylinder firing position, adjust the following valves:

Exhaust valves 1, 5 and 6.
Intake valves 1, 2 and 3.
NOTE: Even numbered cylinders are in the left bank and odd numbered cylinders are in the right bank, when viewed from front of the engine.
.

Just curious, when you're doing this, how do you know which is intake valve and which is exhaust valve? Are there visibly different?
 

bustermin

Banned
Joined
Apr 13, 2009
Messages
315
Re: Adjusting Valves

Easiest way is look at the exhaust port on the head, whichever valve is aligned with it is the exhaust valve. if you have the ehhaust manifold installed, the port will be between the bolts.
 

Don S

Honorary Moderator Emeritus
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Messages
62,321
Re: Adjusting Valves

attachment.php
 

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captmello

Captain
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Jun 30, 2008
Messages
3,826
Re: Adjusting Valves

Why don't you want to do it with the engine running? You could have it done in no time. Much easier IMO.
 
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