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Hi All

Looking at upgraded my going rusty standard exhaust and perhaps the  manifold, I have noticed that the inlet and exhaust manifolds are bolted together from underneath with 2 bolts going through castings on the exhaust manifold, pictures of after market exhaust sports manifolds do not seem to have these brackets, I realize that 2 alloy su carbs don't weigh very much so is this idea to support the inlet manifold and does it not matter if its left unconnected to its mate, I know that  the 4a manifold is different, is that bolted to the inlet as well? 

                      Phil..

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HI, I've just put the standard inlet manifold back on my TR4 after removing it to fabricate an alternator heat shield and to refurbing the starter.

I noticed the two holes in the standard manifold and re-tapped/cleaned out the threads in the two holes in the inlet manifold (5/16 unf I recall), but the bolts (screws) were missing initially and I decided not to put any back as I'm not convinced the method of holding the manifolds to the head is that secure, although it does seem to be standard across Triumphs of the era and I was concerned that it might put pressure on the manifold and pull it slightly away  from the head at the top causing air leaks. Mine has not had any bolts connecting the two manifolds together for at least 5 years if not longer (depending when one of the PO's removed them) and has had no noticeable impact.

 

Mark

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1 hour ago, ctc77965o said:

Yes on a 4A they are bolted together, the 4A manifold will eventually crack if not properly supported. 

The cracks in the manifold are are a function of thermal stresses, they ALL have cracked/will crack no matter what you bolt to them, just a matter of time.

Mick Richards 

Edited by Motorsport Mickey
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The cracking is not usually a problem.  As the crack starts to appear it will immediately fill with exhaust emissions - carbon and stuff.

When the crack is big enough to relieve the stresses - quite big but not in two pieces - it will stop cracking further and be blocked off with the carbon and sit there happily.

It is possibly to get them brazed but there is no point.

 

Roger

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HI 

I wondered about the inlet manifold supporting itself if a sports 4 branch was fitted which appears to have no support brackets, also if the 4a manifold is fitted would a single exit 4a sport exhaust fit to a 4 as the standard exhaust is under the axle anyway and all the exhausts pass the the centre section in the chassis?

                           Phil..

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The inlet manifold is quite happy without the support when you have a 4 branch , you will find pretty much all of the available exhausts can be mixed and matched to fit.

Stuart.

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