Mounting heads - problem O-ring

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Bart Elsen
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Mounting heads - problem O-ring

#1 Post by Bart Elsen » Sat Jun 11, 2022 2:42 pm

Hi all

I mounted the heads today to the cilinders, torqued them at 25 ft lbs.......THEN....

.... I found out that all of the 4 (on each side) O-rings didn't seal the head:
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All nuts have the metal washer underneath (what initially was NOT with disassemble of the engine !).
I thought previous engine rebuilder forgot them???

Are there engine types that don't use the metal washers beneath the nuts?
Then they will go deeper into the heads and probably seal the heads, but they will damage the alu bottom areas were the nut toutches the head

Anyone have an explanation for this?

Grts
Bart

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David Jones
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Re: Mounting heads - problem O-ring

#2 Post by David Jones » Sat Jun 11, 2022 2:53 pm

The early heads do not require that washer but the later heads do. Remove them all and try again.
If I had known I would live this long I would have pushed the envelope a little harder.
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Re: Mounting heads - problem O-ring

#3 Post by Bart Elsen » Sat Jun 11, 2022 2:57 pm

If I just remove the matal washer on the longer nuts (lower row) would it be good to go?
And just leave the metal washers on the top (shorter nuts)

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Re: Mounting heads - problem O-ring

#4 Post by David Jones » Sat Jun 11, 2022 4:18 pm

No reason that will not work as the requirement is to compress the "O" rings to prevent all the oil leaking out of the valve compartment.
If I had known I would live this long I would have pushed the envelope a little harder.
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Re: Mounting heads - problem O-ring

#5 Post by DaveErickson » Sat Jun 11, 2022 5:35 pm

The later head nuts have a ring around them. They are shorter by the thickness of the head washer, provided you are using the original head washers and not generic washers from the hardware store.

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Re: Mounting heads - problem O-ring

#6 Post by Bill Lawless » Sun Jun 12, 2022 7:06 am

Bart Elsen wrote:
Sat Jun 11, 2022 2:42 pm

All nuts have the metal washer underneath (what initially was NOT with disassemble of the engine !).
Is it possible the original washers were there and just stuck in, then you doubled up?
I had them stuck in and it's hard to tell...
 Thanks,
Bill
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Re: Mounting heads - problem O-ring

#7 Post by C J Murray » Sun Jun 12, 2022 6:37 pm

When the heads are removed from the engine and you think the washers are removed then put your magnet on a stick down the hole to assure that a washer is not stuck in there. They often jam in position and they need to come out. If they are really stuck then use a tap to remove them.
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Re: Mounting heads - problem O-ring

#8 Post by Harlan Halsey » Mon Jun 13, 2022 5:50 am

With parts in like new condition, you can get away with mindlessly assembling. However, with used parts of unknown providence you need to know what needs to be done to return the assembly to functionality. Concentrating on the cylinder head hold down nuts using the aluminum rockers, you need to end up with about .030" (.75mm) compression on the sealing washers, and the rocker mounting surfaces of the three head nuts all at the same height. You achieve this automatically with like new parts. But if the nut seats in the head are worn, they need to be resurfaced flat, and replacement washers of the correct thickness made and installed. Occasionally the rocker box floor has been distorted by over-compressing the sealing ring and then further remediation needs to be undertaken.

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Re: Mounting heads - problem O-ring

#9 Post by Bart Elsen » Mon Jun 13, 2022 12:41 pm

Problem solved.
Removed the washers and now all o-rings are nice compressed.....lets hope they dont leak :-)

Now to continue I have to mount the cast iron valve rocker stands (they only have two 17mm bolts at each side).
I cant find the correct torque spec for these rocker stands

I know the maestro says 29ft/lbs but he has the aluminium version stands, and at a manual I even see 36ft/lb.....so quite some difference

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Re: Mounting heads - problem O-ring

#10 Post by Bill Oldham » Mon Jun 13, 2022 8:38 pm

Harlan, Not sure what you mean in the leveling advice. What is it that is compressed .030" and how is it measured?
To be honest, I never gave the base mounting surfaces of the rocker stand heights much thought, just installed em. Hope I was lucky
Is there an easy way to measure the height of the bolt surfaces surfaces to be sure they are in a plane?
Thanks,
Bill

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Re: Mounting heads - problem O-ring

#11 Post by Harlan Halsey » Tue Jun 14, 2022 3:30 am

Bill,
The sealing ring needs to be compressed to seal. Measure the o-ring thickness then measure the head to bolt gap.
A straight edge across all three bolts will do it. Link pin shims are the right size to get close enough if you are close to begin with. (Too much compression and the o-ring will break, resulting in a big oil leak which will probably be attributed to a leaking push rod tube.)
Porsche did it for you, but if your heads have suffered, then you need to re-create the geometry: A milling machine with a 19mm piloted end mill is a big help to clean up the head, and the thick washers are made on a lathe.

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Re: Mounting heads - problem O-ring

#12 Post by Bart Elsen » Tue Jun 14, 2022 5:31 am

Can anyone here confirm the torque spec for the cast iron valve rocker stands (they only have two 17mm bolts at each side).
I see values depending from 29 till 36 ft/lb.....so quite some difference

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Re: Mounting heads - problem O-ring

#13 Post by barbara skirmants » Tue Jun 14, 2022 7:28 am

36 is good for the iron stands.
Vic
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Re: Mounting heads - problem O-ring

#14 Post by Bart Elsen » Tue Jun 14, 2022 11:57 am

So that will then be ± 49 Nm that i will have to apply

(We here in Belgium work with Newton meter Nm)

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Re: Mounting heads - problem O-ring

#15 Post by Martin Benade » Tue Jun 21, 2022 10:08 am

For previous washer discussion the upper and lower nuts that need washers have a groove at their midpoint to identify them. The heads A-C are all cut to the same depth.
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