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Twin cam head for the L6 from Derek at Datsunworks


Derek

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There was some corrosion in the hole.

 

85 lbs is the spec. on the kit. 70 lbs is the spec. for a 10mm 220,000 psi stud in their general torque value chart.

 

I'm leaning towards 65 lbs and calling it a day. It's a low compression NA motor.

Just for the hell of it, here's the old spec sheet from my head studs:

https://lh3.googleusercontent.com/-CQ13kNRteRo/SRQ7qAW99AI/AAAAAAAAAFQ/nsZu0nAGbho/s1024-Ic42/Arpspec.jpg

 

Can't imagine how anybody could be confused...  :mrgreen:

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^^^"Embedment" is the term. Generally from the head gasket compressing, but fretting of the soft metals can do it as well.

 

Some L-Heads frequently torn down will have hardened steel inserts under the head bolts. They are shrunk--pressed into the head and become a permanent part. Stops the embedment phenomenon cold. A properly sized diameter hardened washer under the bolt or nut head will similarly stop the phenomenon.

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Well if there is one thing we can all agree on ARP instructions suck at best and are destructive at worst.

 

I'm going to install the timesert and have another go. I'm going to take it to 65-70 lbs. I'll recheck it after it sits for a while and see how it feels. 

 

Re-torquing after heat cycling is a bitch because you have to pull the cam towers to get to the head bolts. 

 

Derek

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If in doubt, use the Nissan method, after warmup, back off half a turn, then retorque...

NEVER re-torque a head when it is warm. 

 

That is _not_ the Nissan method.

 

You only want to do this when the engine is stone cold, as in sat overnight without running.  You _should_ run the engine through a few heat cycles before re-torquing, but let it cool off completely before re-torquing.

Edited by TimZ
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NEVER re-torque a head when it is warm. 

 

That is _not_ the Nissan method.

 

You only want to do this when the engine is stone cold, as in sat overnight without running.  You _should_ run the engine through a few heat cycles before re-torquing, but let it cool off completely before re-torquing.

One could argue about how warm an engine is after a "few minutes".  You can see a possibility for mis-interpretation though.

post-8864-0-99331300-1449692134_thumb.png

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What else is the "few minutes" for exactly if not to warm it up?

 

Relax people...

The "few minutes" is to heat cycle the engine - see Tony's comments on embedment above.  The whole point of torquing the head is to achieve uniform clamping force across the entire gasket and head.  How you could possibly make that better by purposely putting the aluminum head into a thermally unstable condition while you are doing it is beyond my comprehension.

 

And people wonder why their Felpro head gaskets keep blowing...

Edited by TimZ
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Probably a good time to change the subject:)

 

Did the Timesert and got the head on and torqued to 65lbs.

 

20170707040804-b66c5fa4-me.jpg

 

 

This abomination is the water outlet. It's what I had to do in order to not have to make a separate timing cover pattern for this build. It's setup for the stock nissan outlet and when it's on it won't look too bad. The new design is completely different.

 

20170707040809-d52ef600-me.jpg

 

Upper timing gear went right on and my custom chain stop popped right out.  Ignore the grey silicone if you don't mind:)  The outlet is o-ringed against the head and is bolted directly to the head so I'm not worried about leaking. Obviously I'll have to rework the upper timing cover patten to clear the tensioner.

 

20170707040807-e7c816f2-me.jpg

 

 

February. There I said it.

Edited by Derek
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Wow, seeing it all assembled like that...that stock water outlet will be reeeeeeally close to the distributor (but above it slightly, right?)

That is close!

 

Also, there is a translation error in that head torquing procedure. The English equivalent of what the Japanese characters are roughly translated at best. There is a phrase in Japanese that means "The same, but different" and UNIVERSALLY is translated as "The Same"... Which, is NOT literally what it means. It should be translated into 'similar' but it's FAR more complex a meaning.

 

In all the time in Japan I witnessed the torquing done COLD, and after warmup and COOLDOWN. The torquing is to be done in an 'equalized state' and the kanas say to warm it up and retorque in equalized state. Meaning stone cold (or in the case of VW 122C which is Tuteonically precise but old VW Mechanics will chide you as being TOTALLY WRONG because the valve lash is way too tight compared to stone cold setting as called for originally and for about the first 40 or 50 years the engines were in production when the change came in (to accomodate Americans who were upset they couldn't drive in for a valve adjustment and were upset they had to leave their car overnight...)

 

But hey, they were perfectly willing to pay the 3 hour flat rate change for cooldown waiting on the service rate change... Imagine that, a German engineer with an MBA...

Edited by Tony D
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Wow, seeing it all assembled like that...that stock water outlet will be reeeeeeally close to the distributor (but above it slightly, right?)

That is close!

 

People still use distributers?

 

V2 water exit is behind the front face of the head so you luddites can run your Mallory dual points :)

 

I run EDIS so it's not an issue.

Edited by Derek
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Look what UPS just dropped off!

 

20170707040813-fee25a46-me.jpg

 

Very happy with the first pour. I had what's called a "short run" where the metal didn't flow all the way. It's right at the firing order.  The 1 and 5 are barely there. The metal made it it just didn't fill. There was a hole below it that they welded in for me.

 

20170707040816-eb254eb2-me.jpg

 

I'll sand the other numbers down to that level and see if I can make it work. Otherwise off they come.  I'll modify the pattern so that future castings won't have this issue.

 

The lettering is nice and crisp.

 

20170707040819-480ffa40-me.jpg

 

I'm going with Prismatic lite charcoal wrinkle with the lettering and ribs raw aluminum.

 

Yea!

Edited by Derek
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