Steam Powered Z???

[rossiz]

well gang, once again the savvy members of this forum are correct.

first thing i did today was pull the plugs, clean them (they were still wet) and pull the valve cover - i had a nagging doubt that i had somehow screwed something up with the timing chain tensioner and was worried that the chain had jumped a tooth. to my delight, the cam was still perfectly timed and the chain was nice and snug.

there was also a plenty of oil up there, so i believe the system was doing its job. jumped the starter and spun it over to see if the spray bars were working and was appalled at how weak the flow was - it really just burbled out onto the rocker pivots. took the spray bar off and discovered that the center cam tower oil journal wasn't blocked with a gasket, so it was leaking pressure (the spray bar is in two halves, with the two end cam towers providing all the oil and a blank mounting plate in the center). made a gasket for that and it seemed to help, but i believe the force needed to actually spray the cam lobes only comes when the motor is spinning faster. glad i sprung for a quart of zinc additive, hope it performs as advertised. scary how dry things must be after a motor has sat for a few months and then gets started up...

put her back together, pulled the plugs from the thermotime and coolant temp sensor and switched them (thanks s30driver!). gave the key a poke and after a few grumpy blubbers she fired up and as the plugs burned off she ran better and better. loud as all hell with the straight header, but music to my ears :classic: followed blue's advice and ran her for 20 min. w/the throttle linkage pinned to 2K rpms to break in the cam. then shut her off, pulled the valve cover and did a hot lash adjustment - 5 out of 12 needed some attention. will do another check after a few hundred miles when i change the oil out.

couldn't resist taking her up the street to see if i might set off a few alarms or shatter someones windows with the ruckus - too much fun. yeah, i'm THAT guy on the block.

grabbed the bits of oem exhaust i had laying around and hacked off a piece that had a flange on it (from the mid-muffler back), and stuffed it into the old fart-can that used to hang off the back, bolted it up to the header and hung it from the e-brake pivot with a piece of bailing wire to create a surprisingly functional hillbilly exhaust. shocking how quiet it got with less than 6' of junk hung on the header... took her for a longer drive around the neighborhood (raised no eyebrows on this run) and she runs really smoothly. nice idle, smooth revs. i think i need to fiddle with ignition timing and afr a little as it seems a bit rich, but i didn't want to push it for a bit just to let the top end settle in.

btw - getting the cam gear on took some leverage, wound up using a large open end wrench to pry it up against the cam tower till it was lined up w/the cam nose:

smooth running after valve adjust and sensor re-wire:

the rossiz hillbilly exhaust:

running smooth AND quiet:

[240260280z]

and they lived happily ever after

[S30Driver]

Nice work!

Must have been a great feeling on that first test drive.

Headers look great, & the bailing wire just adds the finishing touch to the underside.

Again, good job!

[Captain Obvious]

Awesome. Glad it's coming back together!

I'm surprised you got a spray bar. Aren't you running an internally oiled cam?

[S30Driver]

He purchased a reconditioned N42 instead of reworking his N47.

[Zed Head]

In the big general scheme of things this is how a head swap should go, minus a few hiccups. More power to Datsunparts LLC if he's listening to the customers and fixing his issues. Looks like he almost got everything right on yours. MSA also for the easy header exchange.

Hope I'm not jinxing you. Good luck with it.

Edited July 25, 2014 by Zed Head
Too wordy

[rossiz]

thanks for all the kind words - you folks kept me going during the dark days on this one.

all in all, it was pretty straightforward. in hindsight, with all the parts on hand and having done it once, the whole thing could've been a big single weekend project (minus all the re-conditioning of the intake manifold) and i'm pleased with the results.

yes, the n42 head from datsunparts llc appears to be well done as far as cleaning, machining, assembly, valve job, cam condition, packing, shipping and price. the valve lash was also spot on (for cold adjustment) right out of the box. the only thing that was a pain was all the stripped/knackered threads - most of them on the valve cover bolts, one exhaust manifold stud and one of the intake bolt threads. while these only presented a mild inconvenience to me, i can see how this could be a major issue for someone who was looking for a truly "bolt-up" part. i didn't mind, because the price was great and i got it in a week, shipped to my door, all clean vs. having to deal with a used swap or expensive re-build. fortunately the spark plug threads are all perfect - a much more important bit for me.

i've been doing little around-town drives, got almost 20 miles on it, keeping it under 4K rpm for the first 100 miles or so just to baby the cam a little. hope to get the final exhaust made/installed in the next couple of weeks and looking forward to seeing how it runs/sounds when done. the hillbilly setup is innocuous, with a twinge of "junkyard" burble, but it'll keep me going for now...

[bpilati]

Look at your plugs.

Also crank the motor with the plugs out and EFI depowered. See if coolant comes out.

Check compression cold and also hot.

Could be a cracked head. N47's like to do this...... what's the line on that ZX engine?

http://atlanticz.ca/zclub/techtips/head/crackedhead/index.htm

And here I thought someone was trying something new.