Bad Air Pump Valve?

[Richie G]

As I march towards first road test I've come across a few unexpected things I'm dealing with, one I think is a too rich mixture.  I say that because I changed the plugs and man they were sooted black as coal.  This engine was rebuilt by the PO about 3 years / 2500 miles ago so I'm going to give some leeway here as I am trusting it was done right.  I know what they say about assuming lol, but its a starting point.  I've read a bunch of material on how to balance / tune the carbs and most people say start with the emissions before attempting to balance the mixture.  So I changed the pcv valve (the old was barely working i see after it was off) and was attempting to change the air pump valve but man its on tighter than Ive ever experienced.  Ive tried pb blaster and still nothing seems to want to unfreeze this thing.  I'm scared to wrench on it too hard for fear of cracking or bending the air galley.  So i figured well lets test the 50 year old valve and see what we got.  I connected a hose and can't blow into it at all which is where my questions lies.  With it attached should I be able to blow into it or is there some back pressure in the air galley that would force it closed when the car is off?  i can easily blow through a new valve but its in hand not attached to the car.  My other question is if it is seized shut and the valve doesnt work at all, what does that do to the performance if the pump is basically useless and cant get any aux air into the galley?  Could it be a source of the mixture issue?  Sorry if these questions are newbie but its a specific topic I can't seem to find an answer to here.

[KenFirch]

On mine a 1" wrench fits on the air galley fitting to hold while breaking loose the valve.  Maybe try some heat too, and a second pair of hands.

I tried for a few years to keep my 73 Z stock, working smog pump, new check valve, exhaust manifold, etc.  Never could get it to run good until I plugged the air galley intake, it ran so much better.  I removed and boxed all the smog stuff up, eventually went with a header a few years later.

[Captain Obvious]

On 8/13/2024 at 10:09 PM, Richie G said:

  I connected a hose and can't blow into it at all.  With it attached should I be able to blow into it or is there some back pressure in the air galley that would force it closed when the car is off?  i can easily blow through a new valve but its in hand not attached to the car.

My other question is if it is seized shut and the valve doesnt work at all, what does that do to the performance if the pump is basically useless and cant get any aux air into the galley?  Could it be a source of the mixture issue?

On your first question - The old valve should operate like the new one. You should be able to blow through it towards the exhaust galley, but not in the other direction towards the air pump. Your old valve is presumably stuck shut.

Second question - There should be no link between the operation of that valve and mixture. The pump is supposed to push fresh clean air into the exhaust stream downstream of the cylinder. The cylinder already fired and pushed the spent charge out on the cylinder by the point where the pumped air is injected. Anything injected into the exhaust stream at that point shouldn't affect mixture (or drivability).

[Richie G]

Thank you both for the help.  I'm in a bit of a panic mode because after giving up on replacing this valve due to its welded on locked tight strength, I put everything back together.  I started it up and now I have this major knocking which I'm hoping is just the valve itself.  I can't imagine it being an engine knock from what I've done, it was running very well with zero sound at all prior to me attempting to do this.  The pitch of this seems too high to me to be the engine itself, anyone have an opinion?  Could I have done something by wrenching on the valve that somehow damaged the air galley in a way that this happened?  The valve may have been punctured when I was trying to see if it was operable.  

 

[KenFirch]

Yeah, I’m guessing an exhaust leak somewhere on the air galley.  Dang!  That sucks.  From your video it looks like you’re going for the factory look.  You may want to start soaking the six fittings above each exhaust port in case you need to remove it for repair.  I’m not sure how successful others have been removing the air galley,  I’ve found them tough to get the fittings loose. I’m not sure what year your Z is, but I’ve got a 73 manifold with usable galley hanging on my wall just down the road from you in Elk Grove.

[Richie G]

Well, worst possible scenario.  Cracked the tube off the fitting on cylinder 1 😞  SOOOOO effing mad at myself!  Why Why Why!  I'm sick to my stomach, a year of work, a seat install away from driving it and I do this!!!!!  

OK, rant over and I've got to start assessing my options.  @KenFirch yes initially I was going for the stock look slowly doing this and that, but this may change my whole approach.  I've come to realize this will never without a significant amount of money be a concourse car.  I'm also not looking to race it anytime soon so I need something in between the extremes.  I think i have four options:

1.  Source a new galley and attempt to replace just that.  From what I've seen, its very difficult to find and B its nearly impossible to remove those nuts.  This would require pretty much everything taken off the engine except the exhaust manifold and associated pipes.   Not a great option unless by miracle the nuts come off.  Since the galley is already kaput, breaking another nut in the manifold wouldn't be the end of things.

2.  Source an appropriate manifold and galley already in good working order.  Still have to take everything off but in addition I have to take off the manifold and deal with that and the pipes reassembly.  This is probably a little more work than option 1 because I have to disassemble and reassemble the pipes.  Pro I get the stock look back, con I guess is it basically gets the car back to where it was without any benefit.  I think the mani coming off would be easier than the galley out the manny cause I canb guarantee after seeing the previous owner work he didn't take the two apart when he had the engine rebuilt.  So hopefully mani bolts will be relatively easy to deal with.

3.  Same as 2, take it all off including the exhaust mani but replace it with a plugged mani.  Allows me to eliminate the smog equipment, somewhat resembles stock for non us cars, ties back up to existing pipes.  Benefit or dropping the smog, cleaning up the engine.

4, Go balls deep and tear it all off and get headers as @KenFirch did.  The heck with stock, gets some new shiny stuff to play with, but lots of extra work in dealing with new pipes probably all the way to the tip.

I havent really decided yet and I think the level of effort will determine what i choose, or maybe i start down 1 path and eventually go all the way to headers if I run into trouble. Some of my obstacles will be, I'm really not a mechanic but getting better, have no lift other than a couple of rhino ramps, can't weld if I have to fab something or deal with that type of thing for a better pipe fit, and have never done this before.  I'm definitely not as intimated as I was but still something like this isn't like painting a glove box or even restoring a radiator.

@KenFirch I have a 71 and that offer is super nice of you.  Not sure it fits though?  Question, what type of headers did you get?  What about pipes and the rest of the exhaust?  I did a quick search today and saw MSA has a few sets that are way reasonable and I like that they are flange type without the need for any welding all the way through the tip.  Thats probably something i could piece together from end to end myself, but I saw some complaints about not hanging high enough / limited hanging and at least one person had to go to a shop to have some cutting and welding done to make it fit.  I need something that can bolt to the enghine and just match up and hang / bolt all the way to the tip so its just me and my wrenches 🙂

If anyone reading this could weigh in on my thinking, the four options, offer some others I'm missing or encouraging words that would be super appreciated.  I'll continue to read and think about it along the way.  Is there some type of simple way to plug that hole in the temporary maybe?  Its already cracked off and more than likely I'll never get the tube out of it anyway, whats the harm in drizzling something over the hole lol.

Oh and back to the newbie side for a moment.  I only ran the car twice for maybe two to 5 mins each time once I heard all that knocking.  Did I do anything to the internals at all in that cylinder?  Did I make more of a mess of this than I already have to deal with?  And if I did decide to have to take this to someone because I just couldn't handle the repair myself, is it even drivable for short say 20-30 mile distance?  Or am i really pressing luck and looking for trouble?

 

[Richie G]

OK, kept thinking and maybe I have a hail mary option #5.  What about using JB Weld Extreme Heat to plug the crack? 

https://knowhow.napaonline.com/how-to-use-jb-weld-extremeheat/

Seems like I can easily get to where the cracked air pipe is by just popping the distributor cap off, might not even need to touch the thermostat housing.  I know this is far from the right thing to do, but for someone like me who's not really excited about tearing everything down to the block, even for the replace it with another manifold option, maybe its good enough for now?  My check valve is frozen dead shut.  That smog pump isn't doing anything other than maybe feed fresh air to the backfire valve when needed but I'd probably leave it for now since I can't get the check valve off anyway to properly plug it.  None of the other exhaust ports are getting any fresh air, would plugging this one really make anything worse?  It certainly won't make anything better, but I was about to drive the car like this without even knowing the check valve was dead and was blissfully ignorant lol.  I'll take what miles I can out of it and deal with it down the road (yeah that's what they all say lol).

@KenFirch i think i saw your post from 22 in the exhaust section, looks like you were happy with how it turned out.  maybe I go that route eventually.  Is that shop still around?

[Patcon]

Options:

You could source another manifold and galley - not too hard to install

Replacing the galley is very difficult unless you have an oxy/acetylene setup. They basically weld themselves into the exhaust manifold over time

Remove the manifold and cut the galley and seal up the holes. I did this 30 years ago with mixed results

Or you could go all bling and order one of Sean's stainless exhaust systems. Header all the way out...

You shouldn't damage the motor with the exhaust leak but you can melt stuff from the heat of the leak blowing on things under the hood.

[KenFirch]

Found a new air galley for you: https://jdm-car-parts.com/products/air-galley-for-datsun-240z

Kidding!  Unless it's a must have for a concours Z.

You might try the simple and cheapest #5 option first.  I would try to jam a short 1/2" long piece of tubing (or bolt shank) that tightly fits in both ends of the broken tube, to hold together in alignment without completely relying on the JB Weld.  Might be worth a shot before spending a lot of money.  It'd be a shame to trash all the work you've done so far getting that stock appearance, looks great.  If you need any mechanical help, feel free to contact me.  I'm just an old retired guy with lots of free time lately.

Yeah, I'm satisfied with the MSA 6 to 1 header, good clearance over speed bumps, unless you go too fast.  For performance, there are better ones, but this one suites me fine.  Muffler Tech is still there on Florin Road, a bit of a drive from Roseville with an open header, but the cops will understand, right? 

[w3wilkes]

I'm with @KenFirch  I did the headers. I went the 6to1 ceramic coated headers from MSA with 2.5inch exhaust all the way back. The air pump location is a great place to mount a sanden A/C compressor.

EDIT: For the exhaust I just went to a local shop and had them build it. I got a Magnaflow resonator and Magnaflow Muffler and am quite please with the result. No problem with ground clearance, it's tucked in nicely.

 

Edited August 16 by w3wilkes

[Captain Obvious]

21 hours ago, Richie G said:

Well, worst possible scenario.  Cracked the tube off the fitting on cylinder 1

Bummer. Here's hoping that whatever path forward you choose, it goes smoothly and that's the end of the issues.   

[Richie G]

Thank you all for the well wishes and advice, especially you @KenFirch for the generous pair of hands offer.  Here's what I think I'm going to do and I'm looking at it as a great learning opportunity and challenge rather than a disaster.  After a few days of thinking and listening to the crew here, I think i'm going to take incremental steps so as not to make this too big of a project and waste more time with it just sitting in the garage.  Ultimately I'll end up with headers and new exhaust, but for now I'm going to delete the smog equipment all together by replacing the mani with a plugged AIR delete one I am getting from Junkyard Jenny.  Its the same type I have so should match right up to the existing exhaust.  While I'm at it, I'm also going to swap out the balance tube with a euro style and go balls to the wall removing all the stuff other than the PCV valve and brake booster.  This will require me to get the later brake booster hose for top load rather than the series 1 side one I have now but I can live with that.  Quite a drastic change from my original approach of "near stock" configuration lol.

I think i have all the steps down, and @KenFirch I may contact you if I run into trouble but a couple of quick questions before I start tearing it down while I wait for new parts.

1.)  If I understand the smog delete correctly, and with my euro style balance tube, all that's left is to plug the port on the air filter going to the intake on the smog pump.  I've seen some comments here and there around fuel rated rubber plugs for that but couldn't find anything.  Any suggestions on how to safely plug the air filter port?

2.) Is removing the smog pump as easy as just literally removing the pump, belt, and associated (and frigging newly bought) corresponding hoses?  Anything to "tune or adjust" now that its removed from the belt system?

3.) The euro style tube has no accommodations for the servo diaphragm and control valve.  Do I need to rethink this?  I'm not even sure what those things do and more than likely on this car they are not working right anyway, just like the check valve that got me into this in the first place.

4.) I had recently replaced the AB valve, again trying to get to stock, does this now introduce the opportunity for back fire?  Or is that a dumb question now lol?

5.) Once all said and done, do i have to re-tune the carbs to accommodate anything I've done?  They felt like they were pretty good as I trust the person that did them before I started this.

6.) Am i crazy and did I miss anything?