Exhaust Manifold

[David53]

Quick Question - I am going to get my exhaust manifold ceramic coated to eliminate fuel vaporisation (going to be a hot summer downunder!).

Rather than have the car off the road I have a spare 948cc mainfold - Does anyone know if this is exactly the same as the 803cc or is there some kind of difference?

Thanks

[fussyoldfart]

Look at the gasket sets for both engines. If the gasket is the same the manifold will probably work.

[don58van]

Hi David

This isn't a complete answer to your question, but AFAIK there are at least two manifold designs that came fitted to 948 engines. The earlier one had an aluminium intake manifold that bolts onto a cast-iron exhaust manifold. The later one is a unified cast-iron casting for intake and exhaust.

Is your 948 manifold one-piece or two-pieces?

I can't remember what the 803 manifolds look like.

Regards

Don

[David53]

Thanks for the replies. The 803cc is a two piece casting (aluminium inlet, cast iron exhaust). The 948 one I have is also a two piece.

[mike.perry]

Check the carb mounting studs, the spacings might be different. The 803 used an H1 11/8in carb, the 948 used an H2/HS2 11/4in carb

[bmcecosse]

Ceramic coating won't make the slightest difference - if you want to minimise heat emissions - you need to wrap it in insulating material.

[David53]

I think I'll just send the original manifold and save any confusion. Roy, a recent article in Practical Classics is what caught my eye, where they ceramic coated the manifold from their project Jag. They say it can reduce heat emmission from the exhaust manifold by up to 65% and is more effective than insulating tape. You don't agree?

[bmcecosse]

Absolutely not - but then I 'don't agree' with most of the rubbish in Pratical Classics! Maybe if the coating is 1/2" thick........ Why are you worrying about heat emissions anyway - Millions of Minors have manged just fine without ceramic coated exhaust manifolds!

[David53]

Well, down here we have summer temps over 40c, and the engine bay in my car gets very hot indeed which has resulted in fuel vaporisation. I do a lot of driving in heavy traffic unfortunately hence the need to reduce the heat from the exhaust manifold.

[Chris Edgar]

Have you though of making & fitting a heat shield to go between the manifold & carb to reflect radiant heat away?

I did it once on a Standard Ensign which I was convinced had fuel vaporisation problems in hot conditions....actually it turned out to be the coil which was getting too hot...but it might have helped if it had been the exhaust heat on the carb, who knows!

[faversham999]

with Fuel injection you will get better MPG you could also fit a program control unit All helps

[bmcecosse]

FI on an 803 - interesting concept..........

[David53]

Yes fuel injection prob going a bit too far!! Can anyone answer the original question - 803 vs 948 Manifold - same or different?

[bmcecosse]

You have them both - so just compare them! My guess is that the exhaust manifolds will be the same - inlets different to allow for the smaller carb on the 803.