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'72 240Z Rebuild

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are you notching for clearance due to high-lift cam, or just to de-shroud for flow?

I've got an E31 with exhaust valves for a N head, which are larger and just barely hit the edge of the bore.

 

From zhome.com

E31 HEAD '70-71 240Z

 

This head has a 9:1 compression ratio. The quench area is the best of the Z heads with the exception of the P79. As stated before 280 valves are an easy installation and recommended. A note of caution here , however, if the 280 valves are used with a stock 240 or 260 bore ( they're the same) you will need to notch the block for the intakes. They JUST touch and make a hell of a noise ( take my word on this I know). If an oversize bore is used here then clearance is not a factor ( even a .010" overbore will do). This is considered by many to be the "best" head because of the "better" quench area and higher compression.

 

100_7364-800_thumb.jpg    L26%20block%20relief_thumb.JPG

 

I can't decide which to do here.  Please advise me somebody (named Steve).  :)

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Holy guacamole!  I've been focusing on the exhaust valves but it's actually the intakes that will hit.  Thank goodness I did that to a spare block.  I'll get the intakes out and see where they hit.

 

I almost stepped in a big ole pile of doo doo.  :o

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Wow. Glad you caught that one before it was too late! I don't remember the last time I had that sick to the pit of your stomach feeling when you realize that you just screwed up royal and it's irreparable.

 

No no no no no no no nobody's fault but mine!

 

I think the last time I did that was when it was already midnight, the car show was the next morning, and I had just realized that I forgot to slide the flare nut up the brake line before I put the flare on the end. It was already too short... "I did NOT just do that."  :angry:

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That's my favorite Led Zeppelin song!  EDIT!  One of my favorites, The Ocean's pretty good too, it be easier to name their bad ones than the good.  I can't even think of one right now but I'm about to crank up Nobody's Fault RIGHT NOW.  My neighbors are at work, work's for suckers. 

 

Na na na na na nobody's fault but my-eeeine

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good to see more happening - i'm watching & learning...

 

and thanks for the tip on head bolts, i picked up a set of turbo bolts from courtesy nissan for $60 as well - a $40 savings over the last set i bought from dpllc, and those were the NA bolts...

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My daughter has it now.

My wife came down with it when we were in NJ

I had it over Christmas.

Join the club.

2 hot showers strategically spread over the night helped.

Also the day time and night time combo's of Tylenol Cold-and-Flu (or WalMart Generic) did wonders.

Edited by Blue
  • Like 1

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My daughter has it now.

My wife came down with it when we were in NJ

I had it over Christmas.

Join the club.

2 hot showers strategically spread over the night helped.

Also the day time and night time combo's of Tylenol Cold-and-Flu (or WalMart Generic) did wonders.

I didn't understand why I should take hot showers in the middle of the night but I do now!  My shower will need Rotor-Rootering now for all the phlegm.  You're advice is spot on, as usual.  :)

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Still feeling like crap but this made me feel a little better.  We've had some bad weather so UPS has been 2 days behind but Saturday around lunch I got my regrind and the components that go with it.  I must say they ground it down to nothing!

$400 for everything, regrind, springs and retainers and .190" lash pads.

 

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Rebelo doesn't give you the specs of the cam though do they?   I might have to go that route.  They know what they are doing and it seems pretty reasonably priced!

Edited by HuD 91gt

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looks cool - let us know how the geometry works out w/those lash pads and the rockers you're using. based on my recent experience, i'll be interested to see how a "one size fits all" set works out.

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I decided to take apart my E31 before I give it to the machinest, trying to save him some time.  Well there was a couple of surprises.  It looks like someone has already ground the area around the valve guides and they are steel, checked with a magnet.  The intake valve seats are brass and the exhaust are steel.  It had the shorter Ford valve seals which I ruined when I removed them, I'll get a new set.  I've got a Felpro beside the Viton for height comparison.

 

Should I get steel intake seats or leave the brass?  I'm not going to the racetrack and when I run it up it'll only be quick and short.  The police know me and where I live with my orange 240, small town.

 

Thanks for any advice,

Cliff.

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It looks like the steel valve has sunken into the bronze seat already.

You can see the ridge left by it.

It would be good to change the intake seats.

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Definitely change the bronze to steel........and get the new low profile Felpro Ford seals.....you'll be lucky if the .190's work correctly for all twelve valves. The head looks good....nice water jackets.

Edited by Diseazd

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I figured that would be the answer to my question, thank you both.  So that means the head has had the bigger valves for awhile.  The intake seats do have a little magnetic pull though but nothing like the exhaust side.  I guess beryllium bronze has enough tin in it to attract the magnet.  Oh well, at least the steel seats are cheap but my machinist is gonna get sick of me quick.  I've been smoothing all the sharp edges in the combustion chambers and I tried my hand at unshrouding the valves.  Am I trashing an E31?  I sure hope not.

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I assume you are using the Hg as a guide-though I see no guide lines marked on the head. Don't get under the fire ring of the HG, just the edge. Don't forget to do those nasty spark plug threads in the chamber. Smooth out any threads no being used. 

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Edited by madkaw

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I used a scribe to scratch the outline of the HG.  You can see it, barely.  Do you think soda blasting the bare head would be okay?  I'd like to clean the outside, not getting near the combustion chambers.

 

Thanks Steve.

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