Exhaust Manifold Help 77 280z

[Datsun7]

I have a 77 280z and I am wanting to put a new header/exhaust on. My questions..... do I need to remove the intake manifold to remove the exhaust manifold? Any other things I need to worry about when putting on a header vs the stock manifold? Thanks for any info! Jeff

[SteveJ]

Since the gasket for the intake and exhaust are combined, yes, you need to remove both so you can replace the gasket. Headers need a thicker gasket. A friend of mine who has worked on Z cars for 30+ years uses 2 gaskets with plenty of Ultra Copper spray to hold them together to seal. 

Check for a flat mating surface on the header to reduce the opportunities for leaks. Have new studs available. Be prepared for studs to break, especially any near the exhaust. 

You can get studs from Motorsport Auto (http://www.zcarparts.com/) sold as a kit or from ZCarDepot (https://zcardepot.com/) sold individually. I purchased JIS style M8 nuts from Bel-Metric since the Motorsport Auto kit had the wrong M8 nuts in their stud kit (I actually bought a lot of those nuts for various applications on both of my Zs.). The MSA kit does include spacers, so that is nice.

You'll need to plug the EGR on the intake since you won't have exhaust gas coming up from the exhaust manifold anymore.

[Datsun7]

Thanks SteveJ for all the great info. Sounds like you have done this before..... I was hoping not to take the intake off but sounds like it is a must with the gasket. The thought of drilling out studs is scary as well. GULP!#  Did you notice any increase in HP or throttle response moving to a header from the stock manifold?  Maybe an RPM/ power band increase? Thanks again for your response and info! Jeff

[SteveJ]

I swapped my 260Z to headers, and it wasn't for any performance gains. I had a massive exhaust leak that turned out to be from a huge crack in the exhaust manifold. You can see photos here: https://fiddlingwithzcars.wordpress.com/intake-and-exhaust/

I also had to replace the gasket on my 240Z not that long ago because I had the engine worked on 25 years ago, and I didn't know to re-check the snugness of the nuts on the manifold. Heck, there were even a couple of missing studs. With the low mileage I've put on the 240Z, the studs were no problem. On my 260Z, a good mechanic worked on the car a few years prior and fixed a broken stud. Again, there were no headaches for me.

Sometimes it's better to be lucky than good.

If it seems too daunting, there are a couple of really good Z wrenches in Virginia. Eiji Hosami has Datsun Spirit in the DC area, and Todd Wagner runs Tidewater Z Auto Service near Newport News.

https://datsunspirit.com/

https://tidewaterz.com/

[Datsun7]

I have a similar issue with a broken rear stud and slight exhaust leak so I was thinking maybe a header would be a better way to go since it has to come off anyway.  Appreciate the Z wrench guys..... I actually have done business with Todd Wagner. His shop is about 45 minutes away. Super nice guy but he has too much work going on and its like pulling teeth to get him to respond and commit. Good problem to have I guess.  I will most likely give him another ring before I dive in 🤪 Thanks again for your help SteveJ

 

BTW... how about a picture of your 240?

Here is my 77 280

[SteveJ]

Here's the 240Z

And the 260Z

[Patcon]

My experience has been that headers tend to leak more often than the cast manifold. A high quality header, maybe not...

I just don't think they're as dimensionally stable as the cast mainfold

[Datsun7]

Two Beautiful cars SteveJ! The rims look great on the 260!

[Datsun7]

Interesting point on the header Patcon. I guess I should look at quality if I go that direction...... 

Did you get my PM last night?

[SteveJ]

22 minutes ago, Datsun7 said:

Two Beautiful cars SteveJ! The rims look great on the 260!

Konig Rewinds - They are the popular budget choice.

20 minutes ago, Datsun7 said:

Interesting point on the header Patcon. I guess I should look at quality if I go that direction...... 

Did you get my PM last night?

That is why my friend doubles on the gasket to help with sealing. It usually works, and a high quality flange on the header certainly helps. There are some threads on here discussing that. It's a good opportunity to learn how to use the search functions unless @siteunseenpops in with his indexed search on headers. 😉

[Patcon]

2 hours ago, Datsun7 said:

Interesting point on the header Patcon. I guess I should look at quality if I go that direction...... 

Did you get my PM last night?

Yes, I will reply with some pictures Friday or Saturday

[siteunseen]

There's some good info on here about header flange thickness, straightness and bolting down properly. I have 2 MSA ceramic 6to1 on mine and love them. If I were you and you live in a state without smog testing I'd come up with a plan and do away with the egr stuff since you're basically killing it off anyway.

I have a doctor's appointment in the morning and will post up some searches I remember being helpful when I did my '77 while I sit out in my car waiting. Damn covid! I fart in it's general direction but I'll do whatever to protect my family.