Hi guys,

I'm re-installing a ~0.59 inch thick plenum spacer on a 350z and I noticed the previous owner used some orange colored silicone sealant between the top intake plenum-half and the spacer, but did not use any between the bottom of the spacer and intake plenum gasket. Since this is my first time doing this and I don't know what brand the spacer is, is it okay to use silicone gasket sealant again on this top portion of the spacer and leave the bottom part alone? (new gasket is being installed too)

 

i would suggest to take that spacer out and put in a 5/16 instead.

 

If gaskets are new there is no need for sealant. Have no idea about condition of used gaskets.

 

any reason why? I read the reviews and comparisons and it seems like bigger spacers where making bigger power due to the volume increase in the intake manifold. Besides, I don't have a choice in getting something else, just re-installing after an injector upgrade .

 

i would just put a really thin bead of sealant just in case. it wouldnt hurt...

 

I noticed the Motordyne tutorial calls for covering the lower intake manifold gasket in oil, but if I'm using an OEM Nissan lower intake manifold Gasket, do I just leave it as is? Or, do I also cover it in oil? Thanks..

 

make sure its clean. both the gasket and the other surfaces. the motordyne gasket is a made out of another type of material which i guess works better oil saturated.

 

Ive installed spacers many times... new and used.
I typically run a thin bead of black rtv as insurance, on used spacers.
Its a crap shoot if the used spacer gasket is gonna leak or not.

 

im not saying all used spacer gaskets leak, but ive come acrossed a fair share of them to warrant going ahead and just use the black rtv.

 

You might as well use a sealant. It's not required but it doesn't hurt to have in case yours does leak.