I have 1997 Gto SR NA, I wish to refurbish the Cam / Rocker covers and want to get replacements so the engine is not left open while they are being refurbished.
According to the WWW (I know there is a lot of questionable info out there) there are two types of the rear Rocker cover, I suppose its possible there are more but legend has it there is a difference between the MK1 and MK2 onwards but I have no Idea if this is true.
I have found two different rear Rocker covers they are stamped in relief on the inside with a number one of which is 505 the other is 573 If they are different between the MK1 engine and the MK2 Rocker covers I do not want to do any damage by fitting the wrong one.
I appreciate I could remove the rear Rocker Cover from the car and look for the number but as this will involve removal of the intake manifold and as I said earlier I would rather not leave the engine exposed. I would like to get a replacement ready to go on before I start the Job.
Hopefully there is someone more knowledgeable than me (Not difficult) on here who knows if the differences are real.
Please do not take this as Gospel ! Its just my opinion
OK, after much research on many and Various forums where people say that they have bought rear rocker covers and they did not fit their engine, but there does not seem to be much info on what “It did not fit” actually meant.
My main concern was that there was some internal difference between the two types and that something might make metal to metal contact if the wrong one was fitted, from photographs I have managed to find there are defiantly some differences.
So the best I can come up with is this :
The “Not fitting” is confined to the side CAM side of the Rear rocker cover as far as I can see the MK1 Rear rocker cover has two threaded holes at the Cam belt end of the cover that are in line with each other front to back if standing in front of the car and are designed to line up with the holes in the plastic Rear Cambelt cover.
Where as the MK2 Rear rocker cover also has two threaded holes but the rear of the two holes is offset to the left again if standing in front of the car.
So my assumption is that the remark “It does not fit” refers to the fact that the end of the Rocker cover at the Cam end differs from the MK1 (Gen 1) to the MK2 (Gen2) by way of the fixings for the plastic Cam covers and the fact that the MK2 has a pronounced curved protrusion towards the back of the cover (Nearest to the bulkhead) whereas the MK1 is
I am afraid that this does not answer the question “are these units interchangeable” I am assuming they are not, but it does give an Idea of the two types I have found. The part number for the MK1 (Gen1) is MD173788 and the part number for the MK2 (Gen 2) is MD186132.
From what I have gleaned from my research the change was when the 4 bolt Forged Crank was introduced at the end of the 1992 model year. But I could be wrong and would be delighted if someone can either confirm or dispel this assumption.
