Is it typical to have to modify a exhaust/inlet manifold gasket to get it to fit? Do I just enlarge the stud holes? I've got 2 versions of a gasket and neither fit and align over the studs nicely...

I'm trying to fix an exhaust leak (evident by the soot on the underside of bonnet as well as fluttering noise whilst cruising), but using these gaskets may make it worse...

I didn't use any sealant on the gaskets that's currently installed, but will likely do so when remedying the leak... or would copper grease suffice?

Cheers,
Fred

I’ve always modified inlet and exhaust gaskets to ensure a correct fit and provide a smooth path for the gasses.

Phil

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Find a job you love and you will never have to go to work !

I never use any sealant.

Looks like you have twin carbs, and probably extractors.
Are the inlet manifold, and exhaust manifold the same thickness where the studs go through,
And do you have the large thick mouting washers,
To ensure you have good even clamping pressure on both manifolds?

I have also found that with some extractors the centre pipe does not pull up square to the head, causing a leak from this pipe. From memory this was with a basic three into one.

I've fitted 3 of these in the last few months - 2 to 1275 motors and 1 to 1098.
They were bought from 2 large mini parts outlets as p/n AJM601 as for standard ports, not the 'big bore' version. They all fitted the stud spacings perfectly.
I don't use any sealant/dressing on this gasket.
I did have a vacuum leak on the twin inlet manifold when 1 of the 'egg ring' locating dowels moved slightly when fitting it and wouldn't let the manifold seal.

My old Maniflow medium bore LCB used to leak there because the flange wasn't flat after they welded the middle pipe on.
It took me a while with a straight edge and angle grinder to make it flat and aligned with the other 2 flanges.
Thankfully they are better made now, I have fitted some and all were fine.

I don't use sealant.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Where can these be bought with additional 2 twin carbie inlet manifold locating holes.

In case it helps this is the BMC Australia engineering drawing for the AYG142 gasket used on the Cooper S and Clubman GT twin carby engines.

It would be easy to make a cardboard template from this as a quick way to check the size and alignment of holes in a purchased gasket. Dimensions are in inches.

Click on the image to enlarge, and again to enlarge further.




A search shows a gasket using the AYG142 part number can be purchased from the sites below. Whether they meet the precise dimensions in the drawing is another matter.

https://classicmotoring.net.au/gasket-i ... te-midget/

https://minisport.com.au/products/mini- ... ndard-type

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ex-NSW Police 1970 MK II Cooper S
VMCI #43