I took my thermostat housing off today and noticed that there is another outlet (other than to the rad) on it, which has been welded up. I looked around and it seems like it should go to my intake manifold (N36), which has no water lines to/from it. There is also another pipe welded off on the other side. This all points to my intake not currently being cooled.

What's going on???

Why would anyone (eg PO) want to do that to my intake? Could the cooling jacket be blocked or something? Is this just a cold running emmissions control thing or does it actually help when engine is warm too?

I've never had any problems running when it gets hot, but it does hesitate when it's cold.

Should i make the effort to re-plumb it?

I'm confused...

Hi,

Sounds like you're looking at a closed off carb preheater circuit. Most Brirish

sports cars and some American cars from the sixties used this warm

water circuit to prevent carb icing from the venturi effect of pulling possibly humid air into the cold carb body. Some owners block them off. I'm in the

process of putting mine back into use to help cold weather warmup performance.

joel

Yep Joel said it. Its for heating the intake manifold, not cooling it (though I guess it may have a cooling effect). Its another thing that can corrode and leak, which is probably why the PO blocked it off.

In the US (at least) there was originally a small thermo-controlled valve at the rear of the manifold that shut off water flow at a predetermined water temp. Water was intended to flow ( and heat the manifold) only until the engine got warm.

Thanks for your replies. Don't think i'll have too many problems with my carbs icing here in Aus. If it aint broke don't fix it.

Cabr icing can occur in even 70* degree Faren. temperatures with high humidity..

This naturally strengthens with altitude...

Now this is for aircrafts.. but just a fact... Carbs are Carbs.. on an aircraft or not...

But you'll be fine if your under 3,000 ft sea level

What is the best way to block this outlet off, other than welding. I don't think I will have a problem with carb icing here (Very low humidity all year).

There was also a similar outlet from the lower radiator intake. Both of these connected to my FI intake (which I have just removed). Are they necessary?

Cheers

I capped both of those off when I removed the injection from my car, Kendall. I did not hook up the coolant lines to my manifolds.

I blocked my thermostat to intake manifold outlet with a pipe plug from McMaster-Carr. The threads were BSPT.

As for the lower radiator intake hose, i also would like to know the best way to block that hole.

On my '71 the water for the manifold came from the steel bypass y-pipe alongside the engine. I used a long pipe to transfer the water to the heater hose. I removed the pipes from the manifold and plugged the holes. It makes a clean engine compartment.

I wonder if you could put cold water through this manifold to increase hp for autocrossing or at the strip. You could use a small pump and put a small cooler full of ice on the passengers side. I wonder how this would work? NE1 tried this?

snip...

I wonder if you could put cold water through this manifold to increase hp for autocrossing or at the strip. You could use a small pump and put a small cooler full of ice on the passengers side. I wonder how this would work? NE1 tried this?

Well the theory is right, you would need to richen the mixture as well.

As to how much you would gain, would the expense of the setup make it viable?

FWIW

MOM

On my '71 the water for the manifold came from the steel bypass y-pipe alongside the engine. I used a long pipe to transfer the water to the heater hose. I removed the pipes from the manifold and plugged the holes. It makes a clean engine compartment.

I wonder if you could put cold water through this manifold to increase hp for autocrossing or at the strip. You could use a small pump and put a small cooler full of ice on the passengers side. I wonder how this would work? NE1 tried this?

LOOK AT THE DATE OF THE THREAD YOU ARE POSTING TO!!!! THIS IS A YEAR OLD