@Zed Head ah okay, I see what you mean. Yes that would also make sense. Some might even say that it makes more sense. But then I’d have to change the hose under the dash unless I used one of those coupler things that you use to join two rubber hoses. 

I think that the heater core has two male fittings that poke through the firewall.  Might not be obvious but pretty sure the 240Z's are the same as the 280Z's.

Maybe I misunderstand what you meant  but On my 240 the hoses pass through the firewall and attach to the heater core under the dash one attaches to a valve that can limit the amount of warm water to the core  

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Yeah, the 240's a different in that regard. The 260 and newer all used a metal bulkhead feed through piece for the water to the core, but the 240 did not. They ran the rubber hoses right through the firewall.

I shouldn't have been pretty sure.  I wouldn't think running the hose straight through the firewall was a good idea.  At least I qualified my thought.  Good that they figured out a better way by the 260Z.  

Nonetheless.  If those are original hoses they're ready to blow.  So, at least, something to consider if the hoses are ever changed.

But the hose clamps are still inside the cabin if I remember correctly. I had the dash out once and I replaced the very small hose that I think goes to the valve, but didn’t replace others. I’m still learning about this car, I’ll probably have to take the dash out for something els again sometime. 
Is the hose clamp for that heater hose in question accessible with the dash in? I imagine some things would have to come out first at least 

I think you can access them if you lay down in the passenger floorpan. Bring a flashlight, and lookout for the spider-bros.

You’re most welcome and to answer the question posted by [mention=23570]Siteunseen[/mention] that I forgot to answer, yes it just caps off the “spider/bug” hole created by the first cap that is inside the Y pipe already.

 

Now that’s an interesting coolant setup! I had never seen it go in at the balance pipe end before. Normally it feeds the manifold from below.

 

See my markup in yellow on your photo (and strictly no phallic jokes, that’s the other illicit thread) [emoji12]

 

 

Just looking close at your photo, holy original exhaust manifold Batman! Is that some kind of emissions reducing air injection setup?

3 hours ago, AK260 said:

Now that’s an interesting coolant setup! I had never seen it go in at the balance pipe end before. Normally it feeds the manifold from below.

Just looking close at your photo, holy original exhaust manifold Batman! Is that some kind of emissions reducing air injection setup?

All that stuff is stock 73 / 74 flat top gala. 73 was the first year for EGR and they ran coolant through the balance tube to cool the EGR gasses. And as for the other thing you highlighted... Yes, it's an air injection system to pump air directly into the exhaust stream to continue combustion. Not positive what year they started that, but it was present by 72.

I'm guessing everything you've ever looked at closely already had headers and round tops?

9 hours ago, heyitsrama said:

I think you can access them if you lay down in the passenger floorpan. Bring a flashlight, and lookout for the spider-bros.

I have actually accomplished that. It is not fun. Old stiff hoses near impossible to remove and don’t try to reuse them. Get new hoses first. 

All that stuff is stock 73 / 74 flat top gala. 73 was the first year for EGR and they ran coolant through the balance tube to cool the EGR gasses. And as for the other thing you highlighted... Yes, it's an air injection system to pump air directly into the exhaust stream to continue combustion. Not positive what year they started that, but it was present by 72.

I'm guessing everything you've ever looked at closely already had headers and round tops?

 

Thanks for the education CO! [emoji106]

 

You’re very right sir - I’ve rarely seen the stock manifold on a US 260z or flat tops close up. My 260 came with the round tops and an MSA header. The sound had me at hello!! I was so excited that I even drove off without a receipt or the V5 (our version of title documents)!