Plumbing

[Daddsie]

Just aquired a heated manifold, how does one plumb it into the water system. Do I need to buy a different bottom hose etc?

[Innovator]

Plumb it any way so it gets warm water.

I did mine by tapping into the heater pipes (copper pipe that runs along the top of the engine, I think, it was a long time ago)

You will get more power the colder the inlet charge unless the inlet ices up. So the heating prevents icing. However this will only happen when it is cold, ie winter.

An alternative to heating the inlet manifold is to provide warm air to the carb in cold weather.

John

[Cam]

I personally don't use the heated part, it is only there for economy and can cause problems on hot days (like today) by leaning the mixture out with the obvious associated dangers. Best to leave it disconnected. And as John says, the colder the charge, the more power you will get, so the heated inlet will rob a small amount of power.

To be honest, with a setup like the A-series (carb on top of the exhaust manifold) the carb does not need extra heat, the reverse if anything.

But if you desparately want to connect it then connect it in series with the heater matrix, i.e. make a length of pipe to go from the copper pipe take-off of the radiator bottom hose (next to the water pump) to the inlet manifold and connect the heater pipe that usually connects to the copper pipe to the other end of the inlet manifold.

You can use a small piece of copper pipe to make the junction between the bottom radiator hose heater take-off and the piece you made to go the the manifold.

[Daddsie]

Cheers, read up on it on Vizzards bible. I shall keep the heater disconnected untill autumn.

I was thinking of insulating the exhaust a. for quicker gas flow, b. for cooler inlet manifold. Will that be a problem with icing even with these Mediteranean temperatures?

[Willie]

Have a look at an MGB engine, there is an insulating shield clamped between the carb and the inlet manifold which does the trick and would
be easy to make up. I have had an SU carb ice up in the middle of
a warmish spring day when bombing down a motorway........because I
had turned the air intake on the air filter to face the oncoming air!!
You will not have trouble if you are using the standard air filter because
you can always move the intake to face the manifold if you get iceing.

[Cam]

You could make a shield up very easily out of a piece of aluminium. Grumpy does one already made though, if you fancy the easy option.

To be honest, with regard to the heater part - don't connect it at all, even in winter.

You should be fine without, and you carb should not ice up, unless you use Willie's ram-air kit!!!

Insulating the manifold pipes will not increase air flow, but will simply move the heat further down the pipe and away from the engine bay. probably not worth the effort or expense for the gains produced.

[Willie]

Mr Grumpy's heat shield kit merely protects the carb float bowl
and the petrol pipe to the pump. The MGB shield covers the entire
length of the exhaust manifold and consists of thin metal with a layer
of asbestos on it......it is very effective.

[Daddsie]

I recall reading somewhere that insulating the exhuast down to say the silencer will improve gas flow therefore upping BHP. Theory being that when the hot gasses hit the cold manifold etc they change their molecular structure quickly which causes a rapid slow down in momentum causing back pressure in the bore.

[Cam]

Mr Grumpy's heat shield kit merely protects the carb float bowl
and the petrol pipe to the pump

Ah, I see! not very good then! best to make one in that case, as the MGB one can't be used, as the carb spacing is different from B-series, to A-series. The MG owners club might do one for the 1098/1275 midget/AH sprite which would fit.

With regard to the exhaust insulation:

change their molecular structure

How?? the charge does not change chemically according to temperature.

I would assume that the temperature difference would cause a change in spent charge density resulting in a slight pressure change, but I bet the effect on BHP would be negligible. Otherwise you would get more power before the engine has warmed up (cooler manifold)!!!!

[Daddsie]

No the trick is to keep the exhaust manifold and exhaust pipe as near to combustion temperature as possible.

[Innovator]

One of the main benefits of insulating the exhaust is a cooler engine bay so cooler inlet charge. All the other reasons stated are true but the benifits small.

Picking up air from a high pressure area out side the engine bay is the best way to ensure air as cool as possible. Then insulate the air pipe.

John

[Daddsie]

Depends what you mean by small benefits, if it buys me a pint of Bass every three tank fulls then its a bonus:-)