Tuesday, 12 June 2012

A quieter exhaust?

Today, with the aid of Pete's lift, I started the first stage of the EFI installation on Amanda's estate HOE. With the 2000 Register National starting next week and us planning on using HOE for that, now would not be the time to start major projects. The CW 6-3-1 does have a welded socket at the collector for a lambda sensor, these don't like being subjected to use without being connected electrically. I managed to cobble together a bung for this via a truck parts retailer.
So after removing the exhaust system and downpipe from the old cast manifold I stripped the carbs and inlet manifold off, plugging the coolant hoses to stop too much leaking out. As I stripped this out I noticed damage to the cast item that I would no longer be using.

Obvious in the photo above is a section of metal missing from around the securing hole above cylinders 4 and 5, more obvious in the photo below is the hairline crack developing in the centre where the front 3 and rear 3 cylinder join. This was longer still at the rear! So the manifold had seen it's best.

Another item that had seen it's best was the gasket between manifold and head, this showed signs of blow by at both exhaust and inlet. When undoing the securing nuts, some were no more than finger tight so the blow by was no surprise. Once removed the gasket had 'manifold' stamped on one side and looked for all the world as if it were the original.

The new (to me) CW manifold looks far sexier than the cast item, so after cleaning up the mating surfaces of the head and manifolds, reassemly began. The photo below was before I remembered that Andy had given me some cut down 9/16 spanners, once I tried bolting up the inlet manifold at no.1 cylinder I worked out what they were for and why I shouldn't have left them at home. The first lower stud under no.1 inlet is shrouded by the exhaust runner from no.1. So it all had to be undone, the spreading washer was shaved a little to reduce height and width and the nut was wound on (1/8th of a turn at a time) whilst slidng the exhaust manifold back to the head. I will be investing in some allen head set screws before the inlets are changed to the EFI ones to try and get over this problem.

Once this minor set back was overcome the rest was just a reversal of the stripdown. I just hope the starter motor doesn't decide to give up now! A rear exhaust support bobbin was replaced along with a coolant hose and clips and it was time for the big startup. The car now sounds really nice, this manifold is said by many to flow no better than a 6-2 TR5/6 manifold, but it does sound good, it may have removed a little of the 'boom' that estates with semi sport exhausts suffer with too, BONUS.

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