DeusExMaxima

iTrader: (1)

I am going to install a 5/16" Blox plenum spacer in my 05 Roadster, along with valve cover replacement (out of precaution since there are high miles on the car and it leaks oil).
I read many posts on spacer install, but there seems to be varies opinions as to how to seal the space to the plenum.

Questions:

1. Should I replace the lower plenum lower gasket (6 holes) where it mounts to the engine? Im thinking yes - good insurance.
2. How do I seal the spacer to the plenum? All new gaskets? Keep old gasket on bottom and put new upper plenum gasket (minus the center part) for the top of the spacer? Silicone seal any of it? My thought was to keep the original gasket that will likely be stuck to the top of the lower plenum and run a thin bead of silicone on top to seal it to the spacer and then install a new gasket on top of the spacer without the center part.

bealljk

iTrader: (13)

I wouldnt worry about the lower plenum gasket nor the bronze/zinc insert nissan provided ... I ditched those a long time ago.

My motodyne 5/16" has a thin cardboard gasket that I've coated in oil and it's been fine. If your blox doesnt I'd run a tiny 1mm bead of RTV (not silicone) on both sides and call it good. Make it as even and consistent as possible, give it 20minutes to setup and then re-install everything. If you are NA than you'll be fine.

DeusExMaxima

iTrader: (1)

I am NA. Since I'm going to be doing the valve covers, I need to take the entire plenum off and there is a lower gasket that attaches to the engine. I believe I need that one for sure.

On the lower plenum, there is a gasket between that and the lid of the plenum. I think that is the one you are referring to leave alone and put a thin bead of RTV, in addition to a bead on the lid of the plenum? Basically, lay an RTV bead on each side of the spacer?

bealljk

iTrader: (13)

For what it's worth - I've re-used the gaskets between the heads and the intake manifold and between the manifold and the lower plenum. I take them off, clean them up and set them aside.

If it were me - keep the gaskets between the heads and intake manifold, keep the gasket between the intake manifold and the lower plenum, delete the gasket between the upper plenum and lower plenum and replace with the aforementioned 1mm bead of RTV on either side of the plenum spacer. .

DeusExMaxima

iTrader: (1)

I'm not removing the intake manifold from the head so I'm okay there. You don't think I should replace the manifold gasket that is under the plenum (with the 6 port holes)?

The one shown here https://frsport.com/motordyne-arg-nissan-350z-aramid-gasket?gclid=EAIaIQobChMIvpqt9cCM3gIVR4R-Ch29ewZpEAQYBCABEgIp5fD_BwE

bealljk

iTrader: (13)

nope ... keep the one you have nice, flat and clean and you're good. If you torque the 6 bolts / 2 nuts to spec it'll seal fine....

DeusExMaxima

iTrader: (1)

Sounds good. That will save me a few bucks from not having to buy a gasket set. So just to sum up and make sure I'm clear.... I will reuse the lower plenum gasket and ditch the upper plenum metal gasket in favor of small beads of silicone on each side of the spacer.

bealljk

iTrader: (13)

If it was my engine/setup I'd do exactly that. You can always swap over to a new gasket if for any reason this original isn't cutting it. I would look at the Skunk Racing plenum spacer (as an example) their spacer has a built-in rubber gasket on both sides.

Be sure to clean all mating sides of everything before you reinstall. I would also plug your intake manifold ports with rags or tape them off so no hardware can drop down into the cylinder. I found these stress relieve toys and I use them to plug the ports any time I have the plenum off.

Do you have a torque wrench? and a copy of the factory service manual?

jhc

Agreed with bealljk. My Z1 spacer instructions did not indicate rtv. Assembled completely, ran like **** due to vacuum leak even after torquing to spec. Complete dissemble, coated every surface like he describes and all good. Highly recommend buying/borrowing a torque wrench, inch - pounds preferred, bolts are pretty small and converting 36" lbs to foot lbs leaves you at 3 ft lbs. Mine would not set that low. gl!

DeusExMaxima

iTrader: (1)

Thats what I will do. I have a torque wrench but Ill have to check to see how low it goes. If it doesnt go low enough, Ill get a small one in inch/lbs. I have access to the FSM online. I will follow the torque patterns. I appreciate the help.

By the way, here in California, some of these smog places can get picky and I read about some places failing VQ motors for plenum spacers. To minimize that chance, I painted the side of the spacer aluminum color to blend in with the plenum. I kept the paint off the mating surfaces of course via painter's tape.

DeusExMaxima

iTrader: (1)

I got an inch/lbs torque wrench. I took the plenum apart and decided to get a new lower plenum gasket from the stealership. I figure for $30, its cheapish insurance in case the old gasket did not seal.

BTW, since the Blox kit did not come with plenum studs, should I get longer ones?

BluestreamDE

https://frsport.com/motordyne-516blt...EaAgyrEALw_wcB

If you have a 5/16 spacer, this hardware kit will do just fine.

DeusExMaxima

iTrader: (1)

I have the 5/16 inch Blox spacer with hardware. The only thing missing is the studs. I heard that the existing studs can be unscrewed out a little bit but I would rather replace them with slightly longer studs.

jhc

Yes, you'll need longer bolts. Take the old ones to an Ace hardware, etc.

DeusExMaxima

iTrader: (1)

Ok, so I got my valve covers and spark plugs installed and then it was time to install the plenums. I got my new lower plenum gasket from the stealership ($30) and put the lower plenum on.

Before installed the lower plenum, I double nutted the two studs up top and unscrewed them 5/16". They were screwed into a fairly thick part of the plenum and the nuts are not torqued down to a very high tension, so I figured it would be safe to do that. I had read about others doing it with no ill effects.

The 6 long lower plenum bolts are notorious for snapping off. I cleaned the threads and put a tiny amount of anti-seize compound on the threads. I very carefully torqued them down to the proscribed in/lbs with no drama.

I kept the original metal upper plenum gasket. I took the Blox spacer and spread a thin layer of black RTV on the lower side of the spacer in then set then spacer on top of the metal gasket on the lower plenum. Then I spread a thin layer of RTV on top of the spacer and set the upper plenum (lid) on top of the spacer and torqued the 18 bolts and nuts to specs using several rounds of increasing torque until I reached the proper torque.

I let the RTV cure for quite some time and then started up the car. It ran nice and smooth. Im glad I painted the side of the spacer silver so it blends in with the plenum. With the engine cover on, it will barely be noticeable.

bealljk

iTrader: (13)

easy enough, huh?

did you stuff rags or tap your manifold closed so if you dropped anything it wouldnt ruin your weekend?

pictures my man...

DeusExMaxima

iTrader: (1)

Yes it was pretty straightforward. I protected the manifold from errant bolts and bits falling in by cutting a piece of cardboard in a rectangular shape and pressing it on the studs to hold it in place. It made a nice little ledge to set some of my tools. :-)

Ill take some pics later to show the stealthiness of the silver painted spacer.

Heel Til I Die

iTrader: (2)

Nice! I did the same thing when I changed mine.




Great minds and all...