New Exhaust manifolds MM

Post by **RobThomas** » Sat May 13, 2006 7:13 am

I'm having some manifold face plates laser cut so that I can weld in some pipes. If you wanted to fabricate an exhaust that works then this is the one! I'm making mine as a twin carb first and might think about producing a run of them if there was enough interest.
The tube bender has let me down but I'm hopeful that another can be found locally to roll the exhaust curves.
Does anyone have a recommended "bender"?
I'm in Cardiff/Bournemouth

Post by **Onne** » Sat May 13, 2006 1:39 pm

twin carbs for the 918 sidevalve? Are you talking about this manifold:

That is my shiney, almost as new manifold to go on my series MM

Post by **RobThomas** » Sat May 13, 2006 7:29 pm

Thats a standard single carb version. Mine will be twin carb and have the exhaust stubs all the same length and meeting 4-to-1 before going back to the silencer. I've done it before for my Lenham and my aeroplane engines. Worth quite a few hp.

If I knew how to post pictures, I would.

Rob

Post by **Onne** » Sat May 13, 2006 10:07 pm

I can host them for you if you want!.

onnevds at hotmail dot com

Is your manifold along the line of the Derrington conersion, aka the Silvertop? That had twin carbs. Never seen one in real life though.

Post by **RobThomas** » Sun May 14, 2006 7:04 am

I've got a Derrington Silvertop here. I wanted to see if anyone could reverse-engineer it and cast some new ones. Any suggestions?

Post by **Keith** » Sun May 14, 2006 9:46 am

If you are looking for an example of the twin carb manifold, Mike Perry had one. Drop Mike a PM, you never know he may lend it to you.
thanks Keith

Post by **Scott** » Mon May 15, 2006 12:01 am

Here's the Australian made twin carby set up for the sidevalve:

I cut off the inlet manifold & used the original exhaust manifold.
I wouldn't say it made a big difference power wise but it certainly helped with the torque for hill climbing

.

With new manifold face plates, I'm guessing you'll have a combined inlet/exhaust like this one:

Should make a difference for the little sidevalve

.

Post by **Onne** » Mon May 15, 2006 5:25 pm

these are the pictures from Rob:

I found this rather good!

Post by **paulk** » Mon May 15, 2006 5:45 pm

OK so sticking a supercharger on must be amusing

.

What does that drag the power up to? 35 - 40 bhp?

Must sound great though

Post by **Onne** » Mon May 15, 2006 6:48 pm

Well, I say... I don't know much power it gets, but surely more than that!

Post by **RobThomas** » Tue May 16, 2006 2:21 pm

The blower is actually for a 1098. I only just remebered that I've used a Lucas 23D4 distributor off of a Mini Cooper to replace the seized one on the sidevalve. Same max advance so an easy swop.
The bunch of 'nanas exhaust system is the one I built for my Limbach VW engine on my aeroplane. At 1500 rpm it is not possible to hear it from 150 feet away over the sound of the propellor whistling round. Pretty quiet, and it adds 100+ rpm to the static thrust (equals an extra 3 hp?) I made a 5 foot long silencer that weighs just 2.1 lbs for the whole assembly.
The VW igntion used to be from Lucas SR4 tractor magnetos but I changed it by adding a honda CBR600 alternator where the flywheel used to go and glued some magnets on to trigger a homemade sensor that goes into 2 computerised boxes and a pair of Ford Mondeo ignition coils. I had to drill an extra 4 sparkplug holes into the cylinder heads to give it dual ignition. Interestingly, that mod also gives about 3 hp more.

PS Thanks, Onne!

Post by **Keith** » Tue May 16, 2006 3:54 pm

Not sure who the question was directed at.

The Alta head and Shorrock compressor on my 52 MM convertible does sound nice and pushes the power up somewhat, top speed is increased, plus the time getting there is much reduced!.
Hills from a starting start are also much easier.

I also have a 1275 52 saloon MM with a Shorrock fit fitted, similar to the one in the picture. Improvement in performance is much greater.

Keith

Post by **paulk** » Tue May 16, 2006 4:35 pm

I didn't mean to sound sarcastic about it Onne.

I know they add large amounts torque and can make the sidevalve feel like it has some get up and go, but what I meant is if you start with 27bhp then adding a whopping (and unlikely) 50% is still only 40.5bhp.

But as I said the noise they make is gorgeous.

Post by **Onne** » Tue May 16, 2006 7:13 pm

I didn't take it as sarcastic Paul. The sidevalev in itself is rather torquey. I hope

Post by **RobThomas** » Wed May 17, 2006 10:15 am

I've always wondered why the sidevalves (since the 1920s era Minor) use such restrictive exhaust manifolds and air filters. Didn'y they know about how much power it took to force the air through? The MM exhaust manifold is particularly awful and must contribute greatly to the lack of ooomph. I'd guess that Keiths' car with a decent exhaust ought to be an absolute flyer, assuming the bottom end holds together!!
Incidnetally, has anyone ever found a source of stronger conrod bolts? I haven't looked at these yet since the new rods are covered in goo. Are they metric shanks and Whitworth threads too?

Post by **Alphaone** » Thu Jul 06, 2006 10:14 pm

Hi Rob, Paul Keith Scott..

How is the manifold project coming allong? - I have had a simmilar plan on the back burner for some time, never enough time to actually get it made though... and if you do get youself a decent pipe bender will be interested in a set! needs to be about 3" longer for my ALTA though... My plan was to make long 4-2-1 branches tuned to a nice low RPM for a torquey motor, with a single 1 1/2" SU (easier to set up).

I have some pictures of a twin carb & tubular manifold set on an ALTA, looks prety much like the one in your pictures.

My ALTA goes prety much like a 1098A series, I swaped from one to the other & it seamed to have about the same amount of go, & similar top speed.

I love the pictures of the shorrocks, never actully seen one on a car, mine is in about a thousand pieces in a box...

20 years ago I replaced the stripped Conrod bolts on my engine with metric high tensile cap screws, i had to cut an anti rotation flat on the cap head to do this, the standard bolts are made of chocolate so the 12 grade cap screws are well up to it.

regards

john

Post by **Scott** » Fri Jul 07, 2006 1:43 am

Alphaone wrote:the standard bolts are made of chocolate

Excellent analogy !!

Post by **Keith** » Sat Jul 08, 2006 3:05 pm

The guy who's copying my Derrington manifold is on holiday at the moment, he's back the start of August. I don't want to rush him, as he's doing the work as a favour.

The Shorrock/Alta combination is the icing on the cake as far as getting performance from the 918 sidevalve, lots of torque and great top end speed. I've only had my convertible up to 80+ mph (speedo max!), without pushing it too hard, but the old car has standard brakes, suspension and cross plys, so I have to go easy!!....Regards Keith

Morris Minor Owners Club

New Exhaust manifolds MM

New Exhaust manifolds MM

Exhaust Manifold