Fitting of exhaust and intake manifold/s

[AarhusTr6]

Hi

Think I am getting there and ordering new studs, but this dowel on the moss catalogue confuses me, what is this dowel for?

Link to Moss Dowel

Also my manifold, has only one stud hole in the middle, any reason for this as there are 6 in the cylinder head.

Thanks

 

Richard

 

Edited May 23, 2021 by AarhusTr6

[Phil M]

Richard, This might help

Regards Phil

[AarhusTr6]

Picture paints a thousand word . . 

So intake manifold only has three bolt/studs across the top and the dowels at the bottom.  Why is my middle bottom part filled in??

Rich

[AarhusTr6]

To follow on, they are only needed to help align the fitting, so are superfluous once the big three studs are fitted?

Richard

[jerrytr5]

Phil's photo shows 3 dowels for a PI car as each inlet is separate. Your photo shows a carb inlet manifold which only needs two dowels as it is one piece.

Without the dowels the ports would not line up. No they are not superfluous. Essential.

Put a gasket on the cyl head and make sure the ports line up with gasket. Grind the ports to suit the gasket (assuming head is off, do not allow swarf into the head if in-situ). Then do the same with the inlet & exhaust manifolds. This will ensure you have linear gas flow without any 'steps'.

Jerry

Edited May 24, 2021 by jerrytr5

[FatJon]

I was tempted to remove the dowels, tap the holes and fit studs so I could actually get a real positive clamping force on the bottom of the inlets rather than relying on the big washers to clamp inlet and exhaust flange at the same time. The dowels didn't even fit through the holes on my aftermarket DCOE manifold. I didn't do it in the end as I figured there must be some reason why Triumph did it this way even though it's really not obvious what it may be. I don't hold with the "aligning the manifold and ports" argument. They would be just as well aligned within fractions of a MM with 2 studs as with a stud and a dowel.

I have a slight tick on the my exhaust ports so I think when I take the manifolds off to change the gasket the tap wrench will be coming out to play.

 

 

 

[AarhusTr6]

Thanks

Interesting, but for me, and I am no aircraft designer but understand basic load and physical engineering, and I cannot understand really the need for them, as if you carefully bolt the intake manifold in one by one and have no load, I can see when they do, but someone went to and effort to have them put into the design many moons ago!  Richard

Richard

[John L]

My reason for having the dowels is, the inlet manifold on the PI can be placed/twisted in many different ways because the inlet manifold is only clamped at the underneath by the exhaust manifold, and not aligned by a stud, that you would find on other manifolds. Also there is an importance on a PI to have them in the same plane, because of the individual throttle linkages, that would have to be reset if the manifold was removed. 

John