On Camaros.net, it looks like it’s not uncommon for heat risers to be installed backwards. The AIM does not show it clearly on UPC N10, Sheet A2.
JohnZ had an excellent posting showing a picture and he posted this comment: “The “extension” was used on all cars at the RH exhaust pipe-to-manifold attachment, in addition to the heat riser valve; it supports the inside diameter of the packing, keeping it from disintegrating (it was also used on the other side). The illustration in the A.I.M. is incorrect – it should show the heat riser valve too. If you look in the “non-illustrated parts” sheet at the beginning of the L34/L35/L78 sections, under UPC 6, where it has the line item for “intake & exhaust manifolds & heat control”, it shows the “assembles same as production” symbol (the “heat control” is the heat riser valve). ”
Picture of his engine showing the heat riser valve:
Picture of a heat riser valve on HBC:
Modification by Ed Bertrand to appear factory but don’t have to worry about it sticking.
He also wrote “Perform the below modifications at your own risk”.
