Captain Obvious

Complete Misfire on Three Cylinders

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Oh, and all the exhaust studs also came out easy-peasy, so I was able to cut down the super long ones and even up the ends on all the rest as well. Most of them had burrs on the first threads on each end from the PO grinding them after using a hacksaw. The studs are all cleaned up now.

Here's the super long ones all out. Thankful for small steps that go well:
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I had mentioned my homebrew valve removal / installation fixture before, but didn't post any pics. Not sure I'll be ridiculed for the contraption, but here's what I made.

Here's all the bits and pieces. Some all--thread that I feed through the holes in the head where the head bolts go. The blue stuff is just masking tape on the threads so they don't cut into the soft aluminum of the head. And the black washers are nylon so I don't take the chance that I'll mar the surface where the head gasket seats:
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Feed the all-thread through the head with a nylon washer, metal washer, and nut on each side:
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Then I place a Delrin cup (that I made on the lathe) over the valve spring retainer:
P1150247.JPGP1150248.JPG

And then I use the pieces of steel plate in a configuration like this:
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Put on the other place and once everything is in place, I just tighten down the nuts until the spring is compressed enough to remove the retainers:
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I used tweezers:
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Once the retainers are out, just loosen up the nuts to decompress the spring and everything comes out:
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Yes, it's slow, but there's pretty much zero risk of springing a retainer across the shop. It's very low mental stress and I'm happy with that trade off for speed.

Re-assembly will be reverse of dis-assembly.

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LOL. It never stops. You just have to keep the voices at bay.

BTW - I did not use a milling machine to fabricate my valve contraption.   LOL

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I would use your "contraption" to.. but without the 4 nuts that hold the bolts in the head?  not really necessary ..?  And the ring made on the Lathe can be just a peace of (copper) tubing?

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You could try something like this without nuts on both sides of the head, but I don't think you would like the results. I think it would be unstable and fiddley.  I've called what I did a contraption, but in reality it's an extremely stable, predictable, and reliable system.

I poked a little fun at it because it's a little unusual, but it's actually quite viable.

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So here's a question for today... What do I want to use for exhaust manifold nuts?

I'm looking ahead and I want to use something better than the mix-n-match of nuts my PO used. Of the eleven nuts I took off the exhaust... Ten of them were 1/2 inch, and one (just one) was 9/16. In addition, two of them were stainless (really really bad idea to mix stainless on stainless) and the rest were carbon steel.

Anyone got a part number for something self locking? Distorted thread? I would really like something 12mm instead of the 1/2 inch nuts I took off.

I would really like a set of matched, 12mm wrench, self locking nuts.

And BTW, I discovered that my intake manifold is thicker than my header flange, so that might help explain all the exhaust leaks. Another thread popped up here:
https://www.classiczcars.com/forums/topic/62535-thick-manifold-washers-notched-wanted/?

I'm soliciting input along with the original poster over there.

 

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Here's my answer for today's question.  The one on the left came with my header but I didn't like them so I bought the bigger ones from Nissan.  The first and last holes on my N42 were wallered out so tapping to the bigger size was easy.  I have that invoice at home if you can't make out the p/ns.  

SDC10659.jpg

post-24724-14150819528287_thumb.jpg

Edited by siteunseen

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If you use self-locking nuts they'll probably pull the studs out on the next removal.  Nissan did not even use lock washers.  Actually, they didn't even use flat washers, where the yoke was used.  Stud, yoke, nut was all of it.

The mismatched flange thickness is the standard problem with headers.  John Coffey suggested cutting flat washers in half and tacking the pieces on to the header flange as a fix.  Requires a welder of course, but it was a simple and effective solution.

http://www.carpartsmanual.com/datsuns30/Datsun-Z-Index/Engine-280Z/Manifold-Egr/From-Aug-76

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I woulg with s30's suggestion.  Copper coated, no issue getting them off in the future

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Yeah, I know if I use self locking, it's likely that it will pull the studs out next time. Don't care. I'll deal with that next time.

Thanks guys. Two votes for copper.

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I bought a 280ZX engine and it had bolts instead of studs.  They looked factory.  

Seems like the basic question hasn't been defined.  What are you trying to accomplish by changing from the factory setup?  If you don't care about the studs getting pulled out why not just use thread locker?

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same here on the maxima head, all bolts, looked factory. I still like the after market studs with the hex head ends, but as ZH mentioned IIRC mine came with the 13mm  head and locking nuts, did not like those at all, ended up using regular nuts (12mm hex) on them.

Edited by Dave WM

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Yes, the stock system used bolts everywhere. I found that same thing on the 83 motor I'm working on in parallel with my blowed up one from my 77.

My PO already deviated from stock by installing stainless studs instead of the stock all bolt system. And ignoring the questionable length of the studs he had in there, it worked and I am (at this time) satisfied with that concept. I am NOT, however, satisfied with his choice of nuts that he used on the aforementioned studs.

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LOL.

So today I officially turned a corner and started on the reassembly. Here's the first two valves back in the head. Woot!! :
P1150418.JPG

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Everything went great. But this process does bring up a question for today... I'm using the Sealer Power valve seals. ST-2034:
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The seals went on great using the little condom that came in the box, but after installation, they don't seam very tight against the valve stem. I'm no engine rebuild expert, but in my limited experience the other valve seals I've messed with on other cars seemed to have a tighter grip on the valve stem. Anyone have any input about this?

Just for a point of reference... The weight of the valve itself is enough to pull the valve down even with the seal installed. My previous experience with other seals is that the grip of the seal on the stem would keep the valve in place against gravity. Of course, it would slide if you pushed it, but gravity alone wasn't enough.

Have I got an old dead box of seals, or is that normal?

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can you check the ID of the seal? I have some OE ones new in the bag I will check against those. Just to compare the resting diameter.

did you oil the seal before installing? Somewhere I read you should with reg engine oil.

Edited by Dave WM

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4 hours ago, Captain Obvious said:

The weight of the valve itself is enough to pull the valve down even with the seal installed.

Ow... Don't think thats normal.. maybe after a few years of wear.. not with fresh installed ones.. but.. what do i know.. last time i installed (Original nissan ones)  is 12 years ago.. 😮

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7 hours ago, Captain Obvious said:

Have I got an old dead box of seals, or is that normal?

That's not normal, as you said, the seal should be able to hold the weight of the valve.

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Crap. Well maybe I'll check one more valve to see if it's my imagination. If it's not imagination, I guess I'll stop with the reassembly and get a different brand of seals on order.

11 hours ago, Dave WM said:

can you check the ID of the seal? did you oil the seal before installing?

Dave, Checking the ID of the seal is pretty much impossible since it's bendable rubber. Can't get an accurate measurement. IMHO, the best way would be to place them on a gradually tapered dowel rod and see where they stop and then measure the diameter of the rod there. I don't think a direct measurement with calipers or something like that would work.

And yes, I used a little drop of motor oil on the seals.

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6 hours ago, dutchzcarguy said:

Ow... Don't think thats normal.. maybe after a few years of wear.. not with fresh installed ones

Yeah, that's what first struck me as odd. The brand new ones didn't feel any tighter than the old ones I pulled out.

OK... So probably a little step backwards today. Just when I thought I had a day of nothing but progress!   LOL 

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I got a barely perceivable drag at .028 using calipers.

I have a head on the bench right now. Later today I will check it out by installing the OE seal and see how much it takes to move the valve.

Edited by Dave WM

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