77 & 78 Intake Manifold Compatibility

[ea6driver]

So after polishing up my valve cover with (seems like) about ten different grades of sandpaper and installing it, I'm hooked. It looks great. Now I'm thinking that doing the same thing to the intake manifold is the next logical step in beautifying my engine compartment.

A guy who lives nearby is parting out his 77 Z. Mine is a 78, totally stock. What I want to know is, can I buy his intake manifold, take a month or so to polish it up - just doing a little at a time in my time off - and bolt it right on. In other words, are the intake manifolds on these two year models totally interchangeable, or were there differences between them?

The obvious advantage to this idea is that my Z would still be driveable while I took my time polishing up the replacement manifold.

Thanks in advance for any advice.

[sblake01]

From what I understand 75-76 are the same and 77-78 are the same or so I've been told. Compared a 75 and a 78 in the junkyard and I think they're all the same until the ZX. Fuel rails changed but I don't think the intake manifolds did. It's the exhaust manifolds that were different depinding on whether the head was a N42 or a N47.

[ea6driver]

My head is an N47.

While I haven't had a chance to inspect/compare his intake manifold to mine (that will happen this Saturday), I've noticed that other intakes sold on this website (and on ebay) had separate or individual "tubes" extending from the main manifold body into the head intake ports.

On my 78 manifold, these tubes appear to be "connected" to each other with an aluminum fillament. You can't see in between each of the intake tubes like others I've seen for sale. I know this setup is kinda hard to explain. It's like a duck's webbed feet - picture it's individual "toes" as the intake tubes and the "webbed" portion as this fillament I'm talking about. Not sure if this setup was changed from earlier models for added strength or for "thermal" reasons.

Additionally I've heard others refer to EGR and non-EGR intake manifolds. I reckon I'll have a better idea on their compatibility when I see it in person this weekend.

Thanks sblake01. If any others have any thoughts on this I'm "all ears."

[280~Master]

There are several types of intakes out there. Any EFI intake will fit on your 78and bolt right up. As far as the EGR, there were intakes that were made for different markets. My 76 has a non-egr intake but it is also a non-catalic car. which is stamped on the door plate.

In California you would find that the 76 intakes have an egr and a cat required. You will also find intakes with webbing. These were on 79 and up I believe but they will bolt right up also. Then there is the turbo manifolds, which are much like the ZX manifold if not the same.

So you have

1. Polished intake Non-EGR

2. EGR Intake not webbed

3. Webbed Intake has EGR

4. Non-EGR intake

[sblake01]

My stock California EGR/Cat intake is webbed. The ones I've seen are pretty much all California cars so basically that's all I can speak of.

[ea6driver]

Thanks Stephen,

My Z is a non-California late model 78 (5/78) and it has the webbing. From your discussion, it sounds like the 77 year models probably do not have webbing, but all the connections should be the same as long as it has the EGR.

When I go look at this car Saturday I'll probalbly go ahead and buy his intake manifold and polish it up (even if it does not have webbing). Without webbing, it won't be an exact replacement, but sounds like it will do the job all the same.

Worst case, I'll end up with 2 polished manifolds and just put the original one back on!

By the way, what are the advantages/disadvantages of the webbing?

Thanks again for your insight.

[sblake01]

I think the webbing might have been another attempt by Nissan to lower emissions by lowering heat to the intake.

[280~Master]

I have seen people cut the webbing out when they polish the intake. If you get your hands on a non-EGR intake grab it they are becoming harder to find. I don't know if there is a performance difference with each intake. If there is its not much.

[ea6driver]

Update. I pulled the stock intake manifold off a non-California 77 Z today. It did not have the "webbing" referred to earlier in this thread. Can I safely assume then that the 78 was likely the first year model Z to incorporate this webbing into the intake manifold?

Just an interesting "factoid" I guess. Now to begin the polishing!

[ea6driver]

280~master,

In post #4 of this thread you posted some photographs of various types of Z intake manifolds. The first photo shows a polished manifold. Would you mind sharing with us specifically HOW you got that manifold looking so good?

Please be as specific as possible. I'd like to copy whatever you did to a T! Sanding by hand? Buffing wheels? I'd appreciate your willingness to share the secret!

Additionally, if others have achieved similar results with their polished manifolds, please chime in with your secrets as well. I'm familiar with the hand sanding process of polishing valve covers, but it just seems that intake manifolds don't lend themselves as easily to the same process because of all their curves/irregular surfaces.

Thanks in advance.

[ea6driver]

My last post got pushed down in the pack before anyone chimed in with specific ideas/techniques for polishing the intake manifold, so I thought I'd repost the request.

I've polished a valve cover with good success using the multi-grade sandpaper technique, but an intake manifold is obviously a much more complex part (multiple curves, rounded surfaces, etc.) and I'm hoping there are some "secrets" that can make the process less painful.

Again, thanks in advance

[280~Master]

I have not polished my intake yet. Those pictures are from others cars. I would imagine some power tools would have been used to. I would strart with a rough grade sandpaper then go down. Try the Atlantic site for more detail.

http://www.atlanticz.ca/zclub/techtips/misc.htm