is removing the intake manifold risky?

[siteunseen]

11 hours ago, Jeff Berk said:

I like that valve cover Siteunseen. Right now I have mine polished with Mother's. It's tempting to sand blast it to get that effect. Did you tape over the lettering or buff them out afterwards?

I decided to pull my intake and started the project tonight. I seem to be one of those that likes to tinker with cars as much or more that drive them.  I still have two bolts under the intake to remove that are difficult to get to. I found it odd that the lower bolts don't go through the flange but instead bolt to the block with wide washers that hold the lower flange against the engine. Nothing seemed overly tight so snapping off a stud or bolt is unlikely. 

I blasted the valve cover then went back over the lettering with fine sandpaper.  That's the first one I ever tried and I was using play sand, it's pretty aggressive and leaves a rougher finish but I like it.  Coated with Eastwood Diamond Clear satin, also used that on the other aluminum I bead blasted.

Oh yeah, I did that outside as you can tell from the pics, use an old gasket and screw it down to a piece of wood.  That keeps all the blast media out.  I found out the hard way, once you blast it don't go and try and clean the inside.  It turned mine a funny looking color so I went back and did it over then blew it off and sprayed the clear satin on.  

 

Edited December 2, 2017 by siteunseen

[Jeff Berk]

I didn't know there was a clear coating you could apply to bare metal that was heat resistant.  I'll read up on it but might go with Rust-Oleum Engine Enamel instead because I found it locally at Summit Racing.

I got the last two bolts off and noticed that the inside of the intake is very rough. Would smoothing it out and polishing help performance or would it be a waste of time?

 

Edited December 2, 2017 by Jeff Berk
wording

[siteunseen]

If you lay a gasket over the intake you'll probably see the intake's holes are smaller.  I scribed around mine and used a grinder to match the ports, intake holes are now the same as the cylinder head's holes.  

While you're there, the slide begins but it's winter and fun if you have the right tools. 

Here's a shot of my 280's intake, same way on the 240.

 

[Jeff Berk]

I just realized that the intake manifold gasket is also the exhaust manifold gasket. That being the case, I need to remove the exhaust manifold as well to replace the gasket, correct?

[Dave WM]

yes its a gasket for both. Pretty sure you don't have to remove it, just lift away enough to the gasket over the studs.

Edited December 2, 2017 by Dave WM

[Reptoid Overlords]

Be picky about what gasket you use. From research it seems the Nissan OEM gasket gives the best results, although experienced opinions may differ.

I used a Mahle gasket from rock auto and it took many heat cycles to set.

[Jeff Berk]

Any idea what gasket to get for an N42 head with an E46/E48 intake manifold? My car's a '74 260 but has a different engine and carb setup than original. I would of thought all the 240-280's had the same but that may not be the case.

I'd likely not get an OEM since I need the option to return it if it does not fit.

[siteunseen]

The n42 head is from early 280s. It has the fuel injector cut out on the manifold gasket.  You need square exhaust ports and round intake holes. I prefer Nissan as it has some aluminum backing around the exhaust ports.  They're about $25 from your local dealership,  they'll have to order it but two days maybe?

Google this part number and look at the images. It's what you need for carbs and square exhaust.

14035-E4610

 

 

[siteunseen]

Felpro has a universal for around $15 from chain parts houses.  I want to say there's 3 different ones but I could be wrururu wrong.  '70 thru '74 with square exhaust and round intake. then '75 thru '76 square exhaust round intake with the injector notch, '77 thru '78 round exhaust and intake with the injector notch.

Good luck getting the special order felpro from chain stores that's not damaged.  I got 2 that were bent up all to hell and back.

[Jeff Berk]

I ordered an OEM using the parts number supplied by siteunseen. Thank you for the help. Down the rabbit hole I go...

[siteunseen]

I found the post that shows the difference between the Felpro and the Nissan.  Click "siteunseen replied to a topic" 

Crappy phone pics from me but you'll be able to see the difference. 

Oh yeah, get some of this and lube the threads on everything.  It makes future projects a lot easier. 

Edited December 3, 2017 by siteunseen

[Jeff Berk]

Siteunseen:

I already ordered the gasket from an on-line source. My local dealer is very unresponsive. I have a big bottle of anti-seize but I'm sure I'll never have to remove those bolts again (yea, right...).

I'll likely work on rebuilding, polishing and clear-coating my carb's while I wait until for the gasket to arrive. Thanks to you and everyone else for help. Who know that a simple post "Is removing my intake manifold risky" would generate so much response.

One more question about a hose connection on the front carburetor. There is an inlet shown in the center of this image (stolen from Datsunroadsterranch) to the left of the dome that allows air to enter the carburetor when choked:

It was blocked off by a PO with a small rubber tube with a plug in the end. Should this be connected to something of importance? It seems odd that it's only on the front carb.

Jeff