| got my heads back and straight edge across the springs reveal... [message #226273] |
Sun, 20 October 2013 10:24  |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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I have a question about the height of the spring assembly and if slight deviations across the top of the lifter assembly will hurt me. The heads have been passed by magna flux and the valve seats proved ok. Shall I be concerned about 1/16" or less on all the valve tops? The valve seats look equal. Thanks people!
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: [GMCnet] got my heads back and straight edge across the springsreveal... [message #226275 is a reply to message #226273] |
Sun, 20 October 2013 11:12  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Lawrence,
Reference Maintenance Manual X-7525 Page 6A-
Measuring Valve Stem Height
Whenever a new valve is installed, or after grinding valves, it will be necessary to measure valve stem height. Install Gauge
BT-6428. There should be at least .015" clearance on all valves between gauge surface and end of valve stem. (Valve stem can be
gauged with or without the valve rotator on the valve). If clearance is less than .015", remove valve and grind tip of valve stems
as required on a valve tachment to insure a smooth 90° end. Also be certain to break sharp edge on ground valve tip. Observe an
original valve to determine chamfer. After all valve keys have been installed on valves, tap each valve stem end with a hammer to
seat valve rotators and keys. Re-gauge all valves between valve stem and gauge (.015" minimum) and valve rotator and gauge (.030"
minimum). If any valve stem end is less than .005" above rotator, the valve is too short and a new valve must be installed. NOTE:
There must be a minimum of .030" clearance between valve rotator and gauge. Failure to maintain this clearance will cause rocker arm
and valve rotator interference. Example:
Valve Rotator to Gauge Clearance: .038"
Minus Valve Stem to Gauge Clearance: -.035"
.003"
This is less than .005" and a new valve should be installed
NOTE: the GMCnet may mess up the alignment of the above so: (0.038 - 0.035 = 0.003)
Below is a Joe Mondello tool to check the valve stem height that JimK sells:
http://www.appliedgmc.com/prod.itml/icOid/980
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Lawrence Harrison
I have a question about the height of the spring assembly and if slight deviations across the top of the lifter assembly will hurt
me. The heads have been passed by magna flux and the valve seats proved ok. Shall I be concerned about 1/16" or less on all the
valve tops? The valve seats look equal. Thanks people!
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] got my heads back and straight edge across thespringsreveal... [message #226501 is a reply to message #226372] |
Mon, 21 October 2013 22:58 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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What I was saying is when the tool is used as it was designed and a feeler gauge inserted to check the clearance the reading on one side of the stem was quite a bit different then the opposing side of the. Stem, meaning the tool was not machined square so the readings are not accurate only general somewhat ballpark depending what side. Of the valve stem you put the fealergauge.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] got my heads back and straight edge acrossthespringsreveal... [message #226510 is a reply to message #226501] |
Tue, 22 October 2013 00:09 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Roy,
OK got it.
It seems to me that if the tool was made correctly you would use it to check that all the valve stems were at the same height, what
do you reckon?
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of roy@gmcnet.org
Sent: Monday, October 21, 2013 10:59 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] got my heads back and straight edge acrossthespringsreveal...
What I was saying is when the tool is used as it was designed and a feeler gauge inserted to check the clearance the reading on one
side of the stem was quite a bit different then the opposing side of the. Stem, meaning the tool was not machined square so the
readings are not accurate only general somewhat ballpark depending what side. Of the valve stem you put the fealergauge.
--
Roy
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] got my heads back and straight edge acrossthespringsreveal... [message #226514 is a reply to message #226510] |
Tue, 22 October 2013 00:31 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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That is correct . I don't remember what the tolerance was for each stem but say it was .005 to .015 and with the lousy machine work of the tool one part of the stem measures .009 and the other corner of the same stem measures .020 ? It's close but kind of a guesstimate as to is it good enough? I just made sure I set the lifter preload on all the lifters . Checking the stem height from the head to the top of the stem does not give the same results s using the stem height tool assuming you have an accurate tool.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] got my heads back and straight edge acrossthespringsreveal... [message #226518 is a reply to message #226513] |
Tue, 22 October 2013 00:38 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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| jim kanomata wrote on Mon, 21 October 2013 22:30 |
We sell that tool and know its value.
If the heads were not done right, you'll know.
By the way Joe Mondello and I became very good friends till he passed away over year and half ago.
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I know joe is no longer with us. I'm just saying the tool I have is not square the current ones may be ok but I wasn't lucky with the one they sent me ( you weren't selling the tool when I bought. It or I would have bought it from you).
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] got my heads back and straight edgeacrossthespringsreveal... [message #226673 is a reply to message #226536] |
Wed, 23 October 2013 00:57 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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| Robert Mueller wrote on Tue, 22 October 2013 06:39 |
Roy,
Below you note: "I just made sure I set the lifter preload on all the lifters."
Which I interpret to mean the distance the rocker arm pushed the piston down in the lifter body was the same for all eight
cylinders.
I just checked MM X-7525 and found this:
ROCKER ARM ASSEMBLIES
INSTALLATION
1 . Position a set of rocker arms (for one cylinder) in the proper location.
2 . Lubricate wear points with 1050169 Lubricant or equivalent and install the pivots.
3. Install the hardened flanged bolts and tighten alternately. Torque bolts to 25 ft . lbs.
Since the rocker arms are not adjustable how did do you set the lifter preload?
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of roy@gmcnet.org
Sent: Tuesday, October 22, 2013 12:32 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] got my heads back and straight edgeacrossthespringsreveal...
That is correct . I don't remember what the tolerance was for each stem but say it was .005 to .015 and with the lousy machine work
of the tool one part of the stem measures .009 and the other corner of the same stem measures .020 ? It's close but kind of a
guesstimate as to is it good enough? I just made sure I set the lifter preload on all the lifters . Checking the stem height from
the head to the top of the stem does not give the same results s using the stem height tool assuming you have an accurate tool.
--
Roy
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. I added a small shim under each assembly to put it within the recommended tolerance. A magnetic dial indicator gave me readings to get them all within tolerance. The specs probably came with the comp cam instructions.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: got my heads back and straight edge across the springs reveal... [message #226773 is a reply to message #226273] |
Wed, 23 October 2013 19:04 |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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Thanks gentlemen, I will double check with machine shop and find out if they checked them as they stated. I don't have the tools mentioned and don't know what a preload or how to preload... I will double check the manual. Thanks
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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