Big Bore Exhaust

[dillorto]

Hi,I am looking for some advice on my exhaust system,i am rebuilding my 1098 engine including a swiftune SW5 camshaft,HS4 Carb,The question is,whats the best exhaust system to justify the upgrades,3branch manifold or standard,big bor exhaust or standard,Any advice is welcome.

[bmcecosse]

The SW5 is not my favourite cam - it has v 'soft' timing and stupidly high lift....far far better with an MG Metro cam. Are you sticking with the standard 202 head? A standard exhaust will be fine - I'm using a 3 branch Cooper manifold - works ok, but frankly made very little difference to the performance. An LCB would NOT be a good idea with that limited state of tune on the engine.

[dillorto]

Yes just bought a refurb unleaded standard head,might be better to just keep the original cam?i am however fitting a midget box and 3.9 diff which is why I thought an upgrade might be usefull.

[bmcecosse]

Yes - the standard 1098 cam (AEA 300) is as good as the SW5 - and works well up to 6000 rpm which is the limit with a 1098 anyway! I urge you to find a crankshaft damper to stick on the front of the engine.

[liammonty]

Free flow exhaust is more important than the manifold. For your engine size, people recommend 1 1/2" bore (certainly no bigger). I think an LCB manifold is best for absolute top end power on 'tuned' engines, but a '3 into 1' or even a standard style (but larger bore) manifold can be better for low-down torque and would be fine on your set up. I couldn't justify the cost of an LCB, so got hold of a 1275 Marina manifold cheaply, and got a 1 1/2 " twin box system from Birmingham Morris Minor Centre to fit it. Maniflow only do a system to mate to their own LCB. The BMMC system sounds nice (and not too loud), but a word of warning- it's a so and so to fit without it knocking either the petrol tank or rear shock absorber! I gather the Maniflow system fits really well, but it's pricier. Going to this set up on my engine (overbored 948, MG Metro cam, 295 head and HIF38) made a big difference to the power higher up the rev range, but I think that's a lot to do with the cam that I used (which has longer timing than the SW5). Like BMC, I'd recommend the MG cam if you can get hold of one.

[dillorto]

Thanks guys,great advise.

[MarkyB]

Surely some work on the head would pay dividends?

[bmcecosse]

Well - no - it's not really worth it.....better to fit a decent head in the first place ....... The 940 is best - and not too expensive -but certainly can't be used with the SW5 because of the excessive lift...... A 295 head would be fine - but the price they reach these days is terrifying....... maybe time to put my spare one on the market!

[mike.perry]

I had trouble fitting my BMMC LCB system, I had to turn the front silencer almost sideways to get the rear section over the axle. Why can they not join the sections on the straight piece behind the front silencer instead of the angle over the axle?

[bmcecosse]

LCB will actually LOSE power unless using 731 cam and upwards....

[dillorto]

That's all good points and I have come to the decision just to leave her totally standard apart from the unleaded head,it will keep it original and its not as though im going racing!!!! so I,ll keep her as Morris intended,Thanks for all your info.