A SPECIAL NOTE FOR  PRE-1972 PLUS 8 EXHAUST SYSTEM
by Lorne Goldman & John Worrall

Jw and I have dealt with scores of the pre-1972 +8 exhausts. We too have the same opinion of the other Plus 8 exhaust cogniescente and the wider Rover community who used them.

1. There are problems to fit of normal Morgan performance exhaust systems to these cars. These models began with decent flowing branch manifolds but soon switched, for reasons of cost. to the ones you likely have. Feeble performance. The best idea is a bespoke system

2. You may also need to cut a small “slice” where the front pipe of the manifold may touch the valance at the very narrow point near the alternator ..I have seen the odd car where this has been necessary, those made with the cast iron manifolds.

3. These manifolds rust quickly and inevitably crack. They cannot be found or replaced. The later cast manifolds, used from 1986/7 to 1998, are much better, especially if they have been ceramic coated.  

4. Additionally, in their original Morgan setting, the valences leave little room for fitting the later standard Performance System on these cars, as their original systems had the pipes coming out of a large hole Morgan used to have made in the chassis itself (not a decision of brilliance) which unforgiveably weakened the chassis and created a breaking point.

They made that weakness worse once they started using short gussets to move the breaking point with earlier car at the bulkhead. They ended the gussets at the same hole! When used for an exhaust pipe, the constant high heat through these holes regularly causes metal expansion and contraction at the weak point which makes matters worse. A Perfect Storm. As in other instances, they continued having that hole even with Morgans that never needed or used it after they stopped exiting through the chassis and exited, more wisely, through the valences. To make holes in the valences is simple. even I can do it!!! But it is more tricky with these early Plus 8s.

Apparently, Morgan forgot to inform the chassis manufacturer of this move and the chassis kept arriving for years with this unnecessary hole. The only perfect solution is a chassis replacement. However, one can try welding a long reinforment piece +/- 2 feet along the bottom of the chassis at the weak point BEFORE a crack develops.

5. The original  systems for these cars are no longer easily available or worth the effort to find. They were a power-killer which was sad as the first engines, with their high compression ratio, could put out more bhp than the engine period after.

6. Their wing width does not lend itself to fitting later systems without invasive modifications such as flex pipes, (the surest sign of make-do when it comes to exhausts).
 
7. The valances have to be cut for the downpipes to exit and the joint is very much on the valance of these narrow cars so the hole is not small. Ideally, this shoulld be done with the wings removed so the valance could be removed and flanged for strength once it is marked out on the vehicle. I personally have made these valence holes with later cross-over single pipe Plus 8s re-adopted by Morgan in 1986/7 with the valences in situ. In the former case, the entire steering column should also be removed. The several cars I have seen years ago with this conversion were having other work done, so this was the case, as there is very little room to work otherwise.

8. Take care not to overheat the brake fluid or melt the windscreen washer bottle with the proximity of pipes.

9. From this point, you ideally use 1972/6 style front joining pipe, silencer (preferably straight through) and a tailpipe each side. The latter may have to bent and or flattened to clear the rear wheels.

10. The crossover pipe also heats the engine oil because of its proximity to the sump, and they heat the engine as well. This system is so unpopular that not even the Factory provides a diagram of it in their later parts books as do all others. Apparently they were ashamed.
 
11. People try their best to improve this exhaust..especially since the pre-1970 cars are so popular in the British racing scene. But regular owners are unaware of these issues and not informed by the less-than-knowledgeable people they know..on forums and including dealers. Race cars do not have to worry about road driving dangers.They soon resort to stuff like flex pipes and an installation which exposes the systems to great risk as their pipes will often go below the chassis in an effort to make it fit in any way they can, exposing the exhaust system to road anomalies. (That being said, the sad crossover pipe is smarter with a flex pipe than the original hard pipe in this area is as it lessens the frequency of breakage.) The home stuff or even the modified attempts from professionals focussed on money usually extend below the chassis and then becomes very vulnerable to road anomalies. Hitting one's exhaust system in a Plus 8s not only damages the exhaust system but often damages the engine heads as the steel bolts are ripped out of the softer alloy, requiring remedial repairs or t-serts (ugh!) or head replacement. (ugh!)
Here is a comment from the world's largest Morgan exhaust specialist and installer with a decade's long impeccable reputation:

1. The orginal manifolds crack in the middle, They can be cast welded or stitched but it is a specialist job. 
2. Replacement stainless manifolds should have to go out through holes in the valance not chassis
3. LHD cars could be a problem with the steering shaft UJ bolt or nut hitting the first pipe of the manifold, if a collapsible column fitted. 
4. Javelin type column think it was ok for the  LHDs but not 100% about that. (It can vary from car to car). 
5. One has to replace chassis mounting brackets on both sides to the “L” shape type and at the end of the chassis for the doughnut rubber. 


So this era of Morgans cannot easily follow the community solutions which have been thoroughly tested on rolling roads and over decades. These fitting problem makes it common that homemade or bespoke system be tried.

PLEASE. If anyone wishes to contribute a design they are satisfied with....your early Plus 8 brethren would be interested and I shall post them here for them.

ONE SOLUTION FOR THE PRE-1972 PLUS 8 EXHAUST SYSTEM
by Win Muehling & Lorne Goldman

My good buddy and partner in crime, Win Muehling has been doing a superb restoration of a 1970 Plus 8 (a stablemate for his 1986 Plus 8). Though he lives across the country (Canada) on the Pacific side and I now commute between South America and Quebec (the other side of Canada), we keep in touch with each other's Morgan mischief. :D

Recently, he took a stab at a new exhaust. The original manifolds had cracked (a defect common to all the early manifolds). But he found another set of manifolds, and then enlisted the aid of a bespoke exhaust maker by the name of Specialty Engineering, situate in Delta, British Columbia, just outside of Vancouver.

In brief, it follows the original Morgan 1970 configuration, a cross-over single exhaust but with a wider bore and performance Plus 4 SS silencer. However, I am going to let the pictures tell the story. Gorgeous work.