'Pinning' / Dowelling Intake Manifolds.

Hi Guys,

Starting the build of an N/A 6 Cylinder here, the head is already heavily ported, but change of intake means the manifold needs matching to the head.

Due to the clearance on the studs, its possible to move the inlet manifolds around a little on the studs, so even when port matched, every time you undo or remove the inlet manifold, there's a chance when you re-fit there will be a small 'step' at the joint.

As head flow seems to be everything on these engines i'm keen to try and eliminate it, Question is - do people ever use dowels to locate intake manifolds to the head to ensure the perfect match every time?

Cheers !

That was a common practice, back in the day.

It can be quite tricky, and another option may be to use a sleeve on a couple of the bolt holes. possibly drilling/boring them out to take a light press fit sleeve? If the ID is close to the bolt/stud size it will locate it well enough, maybe some coppercoat to prevent the parts seizing together for des-assembly?

On that, when circular ports were used, the head and manifolds could be machined to take an alignment sleeve/ring that would partly fit in each for correct alignment. This method was even used on some production engines, it's been a very long time but I definitely remember them being used - maybe the old Bedford 214 and 300 engines, maybe the classic Mini A-series engines?

Thanks Gord, I thought I had seen it before, but wasn't sure, It was probably on an old a-series if they have it ! funny enough I also have an old ford Kent engine which also has the same issue, so should probably do the pair!

I'd lean towards to dowel option on the BMW engine as there should be plenty of surface to dowel, I did think about Sleeving the studs but think I prefer the idea of the dowel... I'll report back !

Cheers