The following notes refer to the G.T. exhaust manifold, the G.T. inlet manifold, and their fixtures and fittings. There are no particular problems that I know about with the standard cast-iron inlet and exhaust manifolds used on non-G.T. motors.
1) The Cortina G.T. uses a four-branch exhaust manifold, as show in the following diagram.
Note that the pipes for cylinders 1 and 4 are to the "outside" of the pipes for the two middle cylinders. The reason for mentioning this is that there is a very similar manifold for the Classic/Capri G.T. 1962-1964, where the pipes for cylinders 1 and 4 are "inside" the pipes for the other two cylinders. As far as I know, the two are interchangeable, as I run a Capri manifold on my G.T. Cortina. It runs very close to the gearbox-engine face, but has given no trouble in 4 years.
There are a number of problems and weak spots in the manifolds.
At the very end of the pipe, where it joins the exhaust system, the pipe can often fracture. This can be repaired by welding a new end onto the manifold. (Best done off the car!).
The repair section welded in position on the end of the manifold.
At the very end of the pipe, where it joins the exhaust system, a metal ring (spacer) sits between the manifold and the front silencer box. This is NOT illustrated in my Ford Parts List, but is listed as EOTA 5258. If you do not fit this, all the mounting points on the exhaust system will not match up! This spacer appears to be the same as used on the later Escort. The Escort Parts Books says the EOTA 5258 was replaced by 3026E-9453A. The same part number EOTA 5258 is used on the MK2 Cortina G.T.
Final note on this ring. I picked up a pair of these spacers from a fast-fit exhaust centre, who had a bucket full of assorted rings/spacers. They even gave me them for free!
The Ford inlet manifold is supported by a bracket running from the block to the manifold. The manifold often breaks at the mounting point on the manifold. It broke on my car during our Land's End to John O'Groats trip, and I changed from the Ford manifold to an "after-market" manifold from an un-known supplier.
The second manifold securing bolt, (from the front) is very difficult to reach with a socket, as there is a minimum of space between the exhaust manifold and the inlet manifold. I have had problems on several cars with this working loose. The best solution is to use an Allen bolt.
If the manifold works loose, the symptoms will be stalling when you stop at traffic lights etc. The engine will be drawing air in through gaps in the manifold/head interface instead of through the carburettor. This weakens the mixture. Similar problem occur with a blown gasket. I have had this happen on a couple of Cortinas and on my one and only experience with a Mini.
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Page last edited: 03 October, 2006