Rosko Racing Upper Plenum Install Guide

If you have purchased one of our upper plenums, first of all we thank you for the business!  Here is a quick walk around of our upper plenums to show whats what as far as vac lines, brake booster fittings and the iacv system go.  If you are installing one of these manifolds use this as a guide and as always if you have any further questions please do not hesitate to send an email to and we will do our best to get back to you as quickly as possible.  We are always here to help and support our customers.


What you should find upon opening the box is the following:

Upper plenum (obviously ha!)

IACV relocation plate and hose

Extra vac fittings and 1/8npt plugs

Mounting hardware for installing upper plenum to lower manifold

If you feel you are missing something please contact us ASAP and we will resolve any issue.


Upper Plenum out of the box:


PCV connection:


Backside of the manifold:  Here we show the mounting hardware.  IF you ordered a spacer with your manifold you will receive the correct length hardware to install the spacer as well.  The brake booster fitting is the 90 degree fitting on the left, your existing brake booster hose should hook right up to this, if it it worn or old you may also need to use a hose clamp.  For vac fittings there are 3 available ports left to use.  Included with the manifold are 3 hose barbs and 3 plugs for whatever combination you need.


IACV connection:  If you ordered the manifold for a traditional H series throttle body then you will have also recieved an IACV relocation plate and a 3ft. length of hose.  You will need two pieces of hose so you will cut the 3ft section as needed depending on where you install the mount plate.  There are two mounting holes in the IACV plate on the top side.  These can be used to secure the plate somewhere in the engine bay or to the bottom of the manifold.  There are typically a few available holes on the underside of the manifold that you could secure the plate however it is not made to go anywhere specifically.  Hook the hose up as follows:  “A” on the manifold connects to “A” on the IACV plate and vise versa for the B hose.  Secure the IACV to the plate using the factory hardware and if you wish you can also hook up the coolant lines to the IACV, however most will choose to eliminate this part of the IACV.

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