Snowbird Posted November 9, 2019 Share Posted November 9, 2019 I bought a new exhaust manifold as mine was trash. However the 2 bolt holes on the front and rear tracts are not 5/16 but are 1/2" diameter.The 5/16" studs look lost in those big holes. Am I missing something? Quote Link to comment Share on other sites More sharing options...
Arjan Posted November 10, 2019 Share Posted November 10, 2019 Good Morning, What engine, what fuel and some pics please. Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted November 10, 2019 Share Posted November 10, 2019 Its probably to provide for expansion - which can cause manifolds to crack. This is why many manifold fixings (like 2 inner combined ones on the LR 4 cylinder petrol) are lugs cast into the manifold and cast steel clamps to secure the manifold - and allow it to expand and contract. If its a petrol the register of the manifold on the head is controlled by dowels - and the exhaust is rigidly fixd to the inlet at the centre - form which it will expand outwards. When re-fixing used manifolds its always a good idea to make sure that the movement isn't restricted by rust in the bolt holes - ie clean them out thoroughly. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 10, 2019 Share Posted November 10, 2019 Very common to use large washers on manilfolds, e.g. The old A series engine, as above it allows things to move to allow for expansion, as well as poor manufacture Quote Link to comment Share on other sites More sharing options...
Snowbird Posted November 11, 2019 Author Share Posted November 11, 2019 Thanks guys for the info, you guessed right it's a series 3 petrol. Will get some large thick washers to put on those 4 mounts. The old one had normal 5/16 bolt holes and was a sod to get off and was cracked in numerous places. Will take pics Arjan and post. Quote Link to comment Share on other sites More sharing options...
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