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I'm not taking sides here, but this is not a new problem and certainly not confined to the Austin Seven market. In my experience replacement exhaust systems from spurious manufacturers over the years,for Moderns and Classics, have been notoriously inconsistent fits. It is quite likely that the Austin Seven pipes available today have themselves been copied from dubious replacement parts, but even so the problem would be compounded by the mixing and matching of engines, crankcases, manifolds, carbs etc. which don't necessarily have the same footprint. I suspect that even if a combination of 10 or more pipes and boxes were available there would still be complaints that they did not fit properly. What is preferable, a universal system available at a reasonable price that can be tweaked to fit, or nothing at all?
Location: Huncote on the pig
I have fitted quite a lot of new parts this year, they all needed fettling.
Brake cam outer circles needed turning down a little, brake levers needed filing all round to remove the burrs, brake cable caps needed quite a lot of attention....and so on.
Location: On a hill in Wiltshire
As a long time owner of RN saloons I used to buy SWB front pipes which fitted a standard saloon with a standard engine and pass through the hole in the front cross-member and lengthen to suit. The LWB front pipes were a mile out being made to fit the later combined manifold and pass under the front cross-member. The silencers fitted with no problems. Nobody makes a RN saloon tailpipe, so I bought a LWB tailpipe and cut it down to make two RN ones. That was a disaster because it was too small and took 20 MPH off my top speed, it was made to slide into the silencer outlet. The original RN tailpipe was part of the silencer. So I took the tailpipe into work and the pipe fitters made new tailpipes of the same shape but to fit outside the silencer outlet. When I built my last RN I took the system off one of our cars to a local stainless steel exhaust manufacturer and asked them to copy it. It fitted perfectly and cost about 20% more than one from our suppliers, that was 20 years ago. I realised that the RN being only in production for a year was a problem for our suppliers.
I did try a reliant manifold and carburettor some years ago and found that the front pipe wouldn't fit, until I adjusted it using a drain grid in the road to hold it while I heaved. That was a spare LWB MS pipe I had kicking about.
Gadger, I was thinking along the same lines as you when faced with two very different pipes and speculated that like 'Chinese whispers' they may have evolved as more copies were made. Mine is not a complaint as such, I can accept there will be differences, but more of a plea for outside help and advice. I have limited mechanical skill and only basic tools, probably like a lot of Austin Seven owners and particularly those new to the scene and so what might seem a simple job to those more experienced becomes quite daunting to the novice, so even though the appeal of the Seven is its simplicity, for some of us that is only acquired through lengthy ownership and a willingness to learn; 'tweaking' for some can be a massive challenge. I'm getting there, but am still highly dependant on others like yourself and am grateful the input and for the parts availability that exists today.
It is curious but original road test and present owners generally indicate a performance from the RN as at least as good As RP despite lower c.r and updraught carb. Unless the low cr head breathes better, the exhaust seems to be the difference.(Quoted hp may not be the maximums.)
Can anyone advise the i.d of original RN tailpipe?
And the construction of original silencer or effective aftermarket ones?
Before anyone gets carried away with sand I can recall my father for some reason making a new front pipe that way. It involved a lot of heating of the sand to dry and repeated thorough compacting. The final heat was against firebricks with plumbers blowlamps (kero and white spirit). Welding of standard bends etc would now be far more simple, if not so pretty.
Location: Auckland, NZ
Just to update the forum, I got a friend of mine to cut and weld the new pipe to match the original, and weld the end back on to the original pipe I had to cut to remove from the car, which had only surface rust on examination. The replacement pipe needs some slight adjustment so the original has been used until the engine is run in. I now have another pipe that will need the same treatment and a possible place to have it bent.
Looking back over the thread I notice in my July 24 (3.51) posting I borrowed an 'i' from Ruairidh's name to use elsewhere and forgot to say - sorry Ruairidh!