Metro/Ital manifold--separating intake and exhaust

[Kevin]

But was used extensively on Formula 3 etc

My mistake I didnt realise that application was suitable on a road going Moggie.
Also unless you were wearing extreemly dark the difference between a heated alloy manifold and a cast iron one is difficult to miss.

[bmcecosse]

It's suitable - in the sense that it uses a single SU carb - and gives an excellent flow into the head! But takes up far too much room to be used on a Mini - unless willing to make a 'Weber box' into the dash of course.

[don58van]

You have touched on my dilemma.

I have been torn between keeping the intake close to original in appearance (the cast iron Ital intake) and gaining that extra readily available performance (the Metro intake).

With the help of club members, I now have the luxury of choosing between them.

Kevin--Thanks for clarifying the interface between the HS4 carb and the intake manifolds.

BMC--I was thinking of painting the alloy one black. At least that way, it won't draw attention to itself. As it is an Austin engine, it (the engine) will be painted black--so the painted alloy item will 'blend in'.

This is an aesthetic issue, not a mechanical one--so that is enough about the appearance of the manifolds.

[bmcecosse]

The black paint will attract extra heat into the intake charge !

[don58van]

You caught me out there, BMC.

OK, it will black on the top where it can be seen from above and unpainted alloy below where it will be exposed to large amounts of radiant heat from the exhaust below. Howzthat?

Don

[bmcecosse]

Perfect!

[don58van]

I'm sorry everyone--I'm back another question on this.

I have been carefully studying my co-joined manifolds and grinding and filing away at the area around the join. I have removed quite a lot of metal and it has taken hours. I can see why most chose to simply sacrifice one or the other part.

This slow and cautious metal removal will give much better access for the saw and it makes it much easier for me to see the line I need to take for the cut.

For those who have separated the manifolds, has anyone measured the wall thickness on the centre exhaust branch in the area of the join?

Declan, if you are reading this, have you put yours on the car yet? If not can you use outside calipers or whatever to measure the minimum wall thickness in the region of the join? And what is the typical thickness in that area?

I have tried to get this measurement but it is of course very difficult with the manifolds still joined.

If I can preserve both parts I will regard it as a triumph, but I'm far from certain that it can be done (except perhaps by putting a patch on a hole created in the bottom of the intake manifold).

Cheers
Don

[paulhumphries]

Coincidently I started seperating my manifolds yesterday.
The join is very thin and also concave (look inside the "port" ) so I cann't see how anyone can easilly seperate them without seriously weakening the area on both manifolds.
I'll measure mine later but you are looking at around 3-4mm thick at the thinest part.
Also how are you going to cut concave ?

My advise is cut off just above the exhaust leaving a hole in the inlet that a specialist welded can then add a piece of cast iron (old brake disc ?)

Paul H.

[don58van]

Thanks for that Paul

I too am moving toward the conclusion that there just isn't enough wall thickness on the top of the centre exhaust branch to allow a cut that would leave both manifolds intact. This is the reason for asking the question about measured wall thickness.

Up till now, I have been encouraged by a report (earlier on this thread?) about someone who almost succeeded, except for a small hole in the intake manifold, which he patched. I was hoping to go one better.

As to how I intend to make a cut of the right shape--I can see that a curved cut or possibly two straight cuts will be required if both parts are to be preserved. As I mentioned, I have taken away a lot of metal around the join, which has given me much improved access for a hacksaw and 1mm rotary cutting blade.

I don't think a curved cut to follow the base of the plenum chamber will be possible. However, perhaps two straight cuts (meeting in the middle) could be made from opposite sides--the head side and the carburettor side respectively.

I think some if not all of the hacksaw work will have to be done with one of those handles that let you grip a blade at one end, leaving the other end free.

Thanks again for your insights. And I hope that the surgery on your manifold goes well.

Cheers
Don

[Declan_Burns]

Don,
That photo I posted is actually an outlet manifold 12g797 from a minor that was said to be fitted with a HS4 carb. I measured it and found the metal thickness varied from about 5mm on the LHS and 8mm on the RHS.
Wait and see what Paul measures and go by that as the castings may very well be different.

Declan
(DEC-1964H / formerly HMP 960B)

[alex_holden]

Up till now, I have been encouraged by a report (earlier on this thread?) about someone who almost succeeded, except for a small hole in the intake manifold, which he patched.

I think that will have been me, and yes I'm convinced if the saw blade had been half a mm closer to the exhaust it wouldn't have broken through into the inlet. I used an ordinary hacksaw, a vice, and lots of elbow grease. The problem is you can't tell exactly how close you are to breaking through on either side, so you might be lucky and not break through but I can't see a way to guarantee success. Just give it a go and be prepared to apply a patch if it doesn't work!

[paulhumphries]

I've just finished seperating my Ital manifolds.
The end result, after grinding, looks quite good
I reckon the minimum thickness between inlet and exhaust is no more than 4-5 mm - maybe less

Paul H.

[Declan_Burns]

Don,
Maybe these photos will help, but read my earlier post. I think Paul can offer more accurate information.
Declan
(DEC 1964H/formerly HMP 960B)<br><br><br><br>