Exhaust manifold coating

[halbe]

Hello,

As the fuel line of my car runs extremely close to the exhaust manifold i have looking at several solutions to the heat problem.
One solution is a coating which claims to reduce the temp. by 33 % .
It's called zircotec see: http://www.zircotec.com

Anybody out there with some experience with these sort of coatings?

Regards,
Halbe

[Ronald]

The only real comment that i can make is that they use this ceramic coatings on a lot of high performance cat manifolds.... i know several people with Subaru impreza's that have used this coating on the exhaust manifolds with good effect, to the point where there is no need to wrap them.... which is the other option............ on the impreza's the unseen benefit of this is that as it keeps the heat inside the manifold, the gasses travel faster, and therefore spool the turbo quicker.... however, i don;t think there will be any performance gain on a Minor,..,..... a friend of mine has also used this coating on his TVR.... the cabin temp was becoming unbearable in the summer, so off the manifolds came and got coated.......... the results are quite amazing.......... so i suspect that the temp difference on a tiny minor manifold would be acceptable aswell....

[halbe]

Hello Ronald,

Sound good !
Especially the performance bit
If this works well it would mean that I can safe the original layout of the fuel line with the bottom feed Carb.
Do you know how the coating looks? They can do black so it should be ok.

Regards,
Halbe

[Ian Grace]

Many Minor owners have replaced their bottom-feed float chambers with top-feeders from SV Minor carbs. The top feed can be attached to the bowl at any angle, so the pipe can be lead away from the hot manifold. The downside is that there is then a reduced drop from the scuttle tank to the bowl inlet and fuel starvation can result when climbing hills with a low fuel level in the tank. These top-feeders were designed to be fed from a Petrolift or SU pump mounted high on the firewall, not a scuttle tank with a much lower outlet.

I went down this route with my fabric saloon, which is how I discovered the fuel starvation issue. I had suffered vapour locks with the hot pipe leading to the bottom-fed bowl, which I believe is made worse by highly volatile modern fuels.

[halbe]

Vapour lock is the reason for trying to get the temperature down.
If this coating does what it claims , reduce temp. by 33% , it might do the trick
I think it is something I'll try because i would like to keep the original layout with the bottom feed SU.
If it doesn't work changing to the top feeding route is easy

Regards,
Halbe

[Ken Martin]

I would be extremely surprised if any coating prevented vapourising in this situation. A metal heat shield and air gap may help considerably, but there is not really sufficient space for a very effective one if the original pipe feed arrangement is retained.

I have some slight vapourising problems with modern petrol in hot weather presumed to be due to heat exchange between the manifold and the petrol feed pipe. This has never occurred when on the road, only after a brief stop such as at a petrol station when the engine is stopped for a short time. The engine always starts again easily, but it splutters for a short time – say half a minute - before running smoothly again.

I have always used a bottom feed float chamber. However, many years ago the original petrol tap (which I still have) was replaced with one that feeds vertically into the pipe rather than horizontally to the pipe through the original hole in the fire wall. The replacement tap requires the feed pipe to pass under the fire wall and this route takes it significantly further way from the manifold.

Not many Minors retain the original tap (which are difficult to seal) or for that matter the original type bottom feed float chamber (because they are frgaile). (See pictures. The original hole for the feed pipe in the firewall can be seen plugged).

[Ian Grace]

Ken,

Nice arrangement - do we know what cars these vertical taps were fitted to originally? I think I have one in my box of bits somewhere, and the nut is clearly much easier to get to, although both taps have the same cork seal arrangement. My other thought is that a vertical tap like this would provide an even lower feed to the carb. and therefore much less gravity drop to a top feed carb. bowl.

I built a original-style side-exit tap on the Bed-Pan very carefully - making the best tap I could from four or five other taps and making several cork seals before I was happy, and ended up with a tap that worked and was fuel-tight. But when I shipped the car to England and turned the fuel on, the cork immediately broke up and fuel poured down my beautiful new floorboards! With limited tools, I made up a thin cardboard seal from the car's import documents, smothered it in Hermetite, removed the pin from the brass nut and wound it up tight with the tap in the ON position - so it can't currently be turned off, but at least it is fuel-tight, and the needle in the float chamber (rebuilt by Burlen) is good enough to stop the bowl flooding. My plan is to sort it out when I get it home after Prescott next year, and I was thinking about getting a modern tap from Paul Beck or similar - if I can find one with the same thread as the tank.

The other fiddly thing about the side-exit taps is getting them fibre-washered up just right so when they are tight in the tank, the side exit points in the right direction - so this presumably is another advantage of the bottom-exit type like yours, as it doesn't matter which way the lever is facing. From the taps that I have worked on, and looking at the various combinations of thin washers fitted, it looks like they were all specially washered up during production to point in the right direction when tight?

[Ken Martin]

Ian
I don’t know what cars the vertical tap was fitted to. It is a proprietary item that was probably used on a variety of applications not necessarily exclusively for cars. I have seen new taps like mine from time to time, but you have to make sure you get the right one for a Minor tank as several versions were made with various inlet sizes.

Based on my experiences, a modification like mine is one way to beat serious vapourising problems for anyone intending to drive their car and not just take it to shows on a trailer.

I suppose that the original type of tap could be twisted round and a new hole through the firewall formed to route the feed pipe further away from the manifold.

As a side issue: recently a VSCC scrutineer was unhappy with my petrol feed pipe and would have preferred to see a flexible pipe used. He accepted the arrangement because of the low key nature of the event I was entered for. He has no doubt got a point worth thinking about. If I stick with the original pipe, I will definitely anneal it next time I take it off the car.

Finally, if anyone is reading this and wondering what the original tap looks like – I attach a picture of mine.
Ken

[Toby]

interesting... I suffer vapour lock in the saloon and that's pumped! must try a heat shield but also rather like the look of enamelling the manifold which I believe sports and vintage do, the heatproof paint never seems to last long on minor manifolds.

[ian judd]

Slightly off subject but regarding the cork washers, SU say that when using new cork washers in carburetters they should be first soaked in engine oil for 24hrs. Perhaps this also applies to taps?

Ian

[Ian Grace]

Yes, S&V do vitreous enameling. I sent Mike an M Type manifold some time back but he told me the fins were rusted too thin for the process to be used on it. To my knowledge, he still has it, so if anyone needs one, feel free to have it for a pint.

[halbe]

Hello all,

As with all developments it's old (proven) against new (innovation).
This coating isn't proven on one of our manifolds, but is it worth a try to find out if it works?
I think it is , I do want to keep the original layout under the bonnet so every little thing that helps me to keep the temperature down is welcome . Also the black finish of the manifold should be a lot more durable than the paint widely used now.
Don't wait for the result as it will take another couple of years for me to finish the restoration of VG2007

Regards,
Halbe