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MG Midget and Sprite Technical - US 1500 hot air premix valve - observations

I just got done with a little fix I'd been putting off for years. You're probably familiar with the premix valve that fits on the air filter box on later MG models and draws hot air from around the exhaust manifold until the engine warms up, after which it switches to hot engine bay air...

Well, mine was fitted with an aftermarket duct hose by a PO, crudely duck-taped to the rubber elbow on the valve. I've been running it like this for nearly 14 years now, and finally got tired of the crappy-looking tape.

So I took the thing apart, cleaned all the old tape goo off with paint thinner, and sourced a proper duct hose. FYI, the flex hose that runs from the valve to the shroud behind the exhaust manifold should be 1-3/4" in diameter. This allows a nice snug push-fit in the rubber elbow. My old hose, FYI, was 2" - hence the duck tape.

Another thought, and one I hope to try out soon, is to arrange a cool-air intake for summer driving by removing the mix valve and its hose, and then fitting a flexy hose directly to the air box snorkel (2" fits great), and then running it down into the space between the outer wing and footwell. The idea is that it could then pull cooler air from down inside that space, vs. from the hottest part of the engine bay as it does currently.

Anyway, I just wanted to toss that out for the rest of you US 1500 owners. This all started the other evening, when I met another midget owner with a '79 that's only accumulated 26,000 miles, and is about 99% factory original. I finally saw how that premix air hose was supposed to look.

Cheers,

-:G:-
Gryf Ketcherside

Make sure its an aluminum hose...other wise it will be subject to heat soak

I know I really enjoyed my cool air vent I made for my car last year.

But i think makeing a heat box out of aluminuim, to look like the smiths heater box WithOUT the heater maxtrix and a built in fan would be perfectly Ideal for an even a better cool air vent....In fact maybe a tray with marble chips (grave stone maker/kitchen granit counter top maker) so the air would flow over the top...or thur the stone chips, to create an even cooler vent.


why marble chips? because its cooler temp wise and requires alot of heat to warm it...normal marble temp in shade is like 70 degrees

Prop...Just my 2 cents on what I have done and have looked into doing....Prop
Prop

Easier yet, you could just keep the Smiths box and take the core out.

And yes, I did use aluminum hoses - from NAPA.
Gryf Ketcherside

you can use the original smiths box, but it is made out of steel and will soak up heat like an elephant sucking water in the african seringety.

If you re-make the box out of aluminim it will hold vary little heat soak if any over many hours.

exp. cook up some french fries on a steel baking pan in an oven at 400 degrees for 1/2 hour, and pull out pan with your barehand...trust me not possiable (for most)

then do the same thing with aluiminum foil....as long as you dont touch the french fries or foil making contact with french fries, the foil will be the same temp as when you put it in the oven...try it some time and see.

On a hundred degree day, on a 2 hour drive, Aluminum vs steel, where air cool clean air is passing thur can make a huge differance.

Prop

Prop

>>> the foil will be the same temp as when you put it in the oven... <<<

Yes, but only because the foil is too thin to retain much heat - it's all surface area with very little thickness, so while it heats to the same temp as everything else in the oven, it loses that heat almost immediately when you remove it. Try that with a thicker piece of aluminum, say a skillet, and you're talking blisters big time. It isn't the type of metal so much as the mass.

;-)

-:G:-
Gryf Ketcherside

To keep appearance original and get better insulating properties I would gut the Smith box as suggested, then add to the inside some foam insulating product.

I've seen at Ace hardware stores a duct insulating product that has foam with aluminum backing and an adhesive side. Just a suggestion.
Thor Patterson-Ritz

Gryf,

MMMmmm, I see your point and raise you...

If I "had" to grab a hot skillet and had a choice of Steel and Aluminum...Im thinking Id choose the Aluminum....Gauge thickness for gauge thickness, I think having a replica (smith) heater box made out of aluminium...Is going to be many degrees cooler doing the cool air vent idea for those months of july and Augest

Seriously Gryf,

The main issue you have with this idea is your torn between Orignality vs, Modifcation in order to stay cooler during July and Augest, Am I correct?....Oh Im good, LOL.

Gryf,

If I had your car, Id have the exact same conserns, at one time I did with my car, but the mods just crept up on me, and I can no longer turn back from the dark side, I truly understand the conflict between annikan and vader, in the realm of the midget. All I can say, is once you start down that road its hard to say stop, and say thats enough. And I suspect a temptation not even you are immune from, having that temptation is not a weekiness, its just who we are, I for one love your car, its the closeest I have seen to factory orginal, in every scence of the word.

If anything maybe have a box made to replicate the smith box exactly, then make a mould of the word "smith" and use a 2 part epoxy...(Jb weld) to form the word and glue onto the "new" aluminum box and paint it black then use the new box only during the heat of summer and replace with the original during the rest of the year when temps are more tolerble

Then agian ...Thor has a great idea using duct insulation...coating the inside with a heat resistant material of the box with the heater matrix removed might prove to be a ....COOL....Idea. (yeah I love puns)


Still I think any thing you do to prevent "Heat Soak", is only going to make those long drives in july and Augest more enjoyable

Having given this issue alot of thought, I still belive the original Smith heater box is one of 3 main culprets for summer time cabin heat and its due to "heat Soak"

Prop
Prop

This thread was discussed between 25/05/2009 and 30/05/2009

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