FE-FC Holden Discussion Forum

I am about to fit a set of extractors and in the process are going to change the twin manifold which attaches to the hotbox of the exhaust manifold to a twin manifold made for headers / extractors.

My question is how important are the inlet manifold locating rings in being used. The manifold currently being used has an indent for these locating rings to fit hence I am using them. The manifold I am about to use doesn't have an indent for the rings to bed into. Should I still use the rings as they of course fit into the inlet of the head?

Thoughts would be most appreciated.

Rod

My thought is that they protect the gasket a bit from failure. I would use them again, but it depends whether your new manifold has the diameter machined into the casting.

Ken

A couple of local fb ek owners asked me recently if I new any reason why their sideplates seemed to be missing and running rough.Coincidently they both had their motors recoed by the same rebuilder.I had to go to town for a few hours but promised them I would get back to them with a answer as this was too much of a coincidence not to be something simple.The reco guy had decked the manifold side of the head and had taken enough of as to make those locating rings  not allow the intake manifold to sit flush against the head ,hence the gasket would blow.A few thou off the rings and no problems.Just thought I might put this out there .

Thanks Ken. l needed to be a bit more clearer. The new manifold doesnt have any machining into the casting. Its just straight through. l need to measure up the diameters of the inlet and manifold I suppose.If I use the locating rings I could see them coming loose.

Rod.

The thickness of the ring is .051 thou, the ring is .352 tho and the ring seat in head is 1.24 inch

1.292" is the measurement of my aftermarket match ported intake runners that don't have a step. The rings have a gap so they are a resistance fit, so based on the I would assume that of you aftermarket ones are around 1.292, then you are cooking with gas to have a good fit. If they are slightly smaller, I would slightly taper one end of the ring on a grinder and let the bolts pull it up to a tight fit.

If the manifold you are using doesn't have a machined area for the rings you don't need to use them or it would have somewhere for them to go, you don't use them for extractors and no other engines after the grey used them.
   Pedro