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Exhaust phaaarp

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rlincoln Ray Costa
Gurnee, Illinois, USA   USA
1963 Morris Mini Traveller "Miss Marple"
No question that a two inch exhaust pipe is too big for this small an engine. As a check, I measured the exhaust pipe on my MG TD which has a 1250CC engine and runs at about the same rpm's as the Series A engines. The I.D. is 1.5 inches. If, and only if, you are fitting dual carburetors or a 1.5" carburetor,, and perhaps larger intake and exhaust valves, using 1.5" pipe for an exhaust should be about right. Otherwise, use the factory size. As a side note, the british were extremely conservative in engineering and didn't produce cars in anywhere near the volume that American car manufacturers did. They probably used 1.25" exhaust pipe on nearly everything just for convenience and cost purposes. They compromised a whole lot of design issues so that they could get prices down to a reasonable level. Even Rolls Royce used bought in electrical systems and carburetors. That's why a 1948 Morris uses the same rear axle, tail lights, electrical system, steering wheels, rack and piñon, etc. as does the same vintage MG (and makes my keeping spare parts in the garage so much easier). Just about every British car of 1.5 liters or less uses the same universal joints. We're not talking badge engineering here, we're talking about common parts bin engineering. It's like using a Chevy 350 engine accrues the general Motors line.

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Bloggins Tom Morris
Sechelt, British columbia, Canada   CAN
All that you say is true, Ray, proprietary supplies like Girling, S.U., Dunlop, Lucas, Moss, etc. supplied similar or identical parts to the entire British industry. However, the fact that MG (Morris Garage) was essentially the sporting/racing division of Morris Motors makes for an even closer relationship between those two.

In reply to # 8616 by rlincoln As a side note, the british were extremely conservative in engineering and didn't produce cars in anywhere near the volume that American car manufacturers did. They probably used 1.25" exhaust pipe on nearly everything just for convenience and cost purposes. They compromised a whole lot of design issues so that they could get prices down to a reasonable level. Even Rolls Royce used bought in electrical systems and carburetors. That's why a 1948 Morris uses the same rear axle, tail lights, electrical system, steering wheels, rack and piñon, etc. as does the same vintage MG (and makes my keeping spare parts in the garage so much easier). Just about every British car of 1.5 liters or less uses the same universal joints. We're not talking badge engineering here, we're talking about common parts bin engineering. It's like using a Chevy 350 engine accrues the general Motors line.

old redoubtable alex wilds
columbia sc, USA   USA
1959 Morris Minor Traveller "Old Redoubtable"
1959 Morris Minor Traveller "Old Redoubtable"
I like the parts bin approach. Gratuitously making up new parts helps no one. The big benefit is that fifty years later parts for our cars are common and cheap, new or used.

Regarding the above comment that a bigger exhaust only helps if you have bigger carbs and valves is true, but only if you are racing, spinning way up about 7000 rpm. My experience with a road Morris Minor is that bigger carbs and pipes (and I have tried them all!) does not do jack for you at normal road and highway speeds - the engine just does not demand that sort of breathing. On any stock BMC - A engine in a Morris Minor the stock SUhs2 and 1.25" exhaust system delivers as much usable power, runs better, gets better milage, etc., than any bolt on hop up, save maybe a super charger on the same stock set up.

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tjt77 timothy Trevithick
Grass Valley, California, USA   USA
for a stock 948 engine the standard exhaust is fine.. as posted above..the paarrp is due to resonance in the long pipe after the forward mounted muffler ..
when the stock exhaust got holed from rust, a local muffler shop fabricated 1 3/4 ' system on my 1275cc engined car (with header I fitted before it went to their shop) ..car has an Austin America single HS4 carb (had to change the manifold assy when adding header and adapted a '59 minor inlet) ..there is a very noticeable power improvement with the slightly bigger exhaust and header..both low end torque and at high rpm.much better. ..which defies logic since the header is the bigger bore variant designed for 'top end' only..outlet from header is 2".. it steps down 1/4" at muffler exit..

pvr Avatar
pvr Paris VonRabenau
Reynolds, Georgia, USA   USA
1960 Morris Minor 1000 "Paris VonRabenau"
1960 Morris Minor 1000 "EMMA"
Hi, I will need a new exhaust system. I found EMT pipe used for electrical conduit for sale at home depot. It comes in 1.25 diameter which is the right size and welds with a mig welder. That and a Harley muffler. Anything wrong with this idea?

geezer Avatar
geezer Silver Member charles durning
Magee, Mississippi, USA   USA
1958 MG Magnette ZB "Chick Magnette (sold)"
1967 Morris Minor 1000 Saloon (2-door) "Marvin"
1974 MG MGB GT
The pipe size and the Harley muffler is what the Midget guys use. Just be careful of welding anything that is galvanized. Toxic fumes.



If it was good 60 years ago, does that mean it can't be improved?

pvr Avatar
pvr Paris VonRabenau
Reynolds, Georgia, USA   USA
1960 Morris Minor 1000 "Paris VonRabenau"
1960 Morris Minor 1000 "EMMA"
OK,
Thank you for the heads up. I was going to take it to the welders. I sure appreciate you guys all for your seeming limitless guidance no matter the area of concern. I'll bet your gatherings are something else. Probably can't talk over all the conversations going on at the same time. I like being part of this group of guys being a dyed in the wool motor head.
VON
Too soon old, too late smart, Dad always said.

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