My two-centís worth.
All fuels vaporize under 400 F the blue tips of the burner flame can approach 2500 to 3000 F
The vaporizer tubes should be as high off the burner as you can get it. Saturated steam at 400 psi is 445 F at 600 psi its only 486 F
The closer you get to the bottom of the boiler sheet the cooler your going to be. I understand heat radiates in all directions the same speed as light but is being sucked off rapidly by the cooler boiler sheet.
I was asked if I could fix a burner on a 01 Locomobile as the cables would carbon up within the first hour of running. I said I would look at it \.
See the attached photos the vaporizer tubes was so close a pencil would not fit under it.
I made new vaporizer tubes using 4130 and raised them as high as I could. I also braised the two tubes together the entire distance across the burner to normalize the temperature between them.
He now can run all day; no carbon and the cables come right out burning straight gasoline.
My own EX is also as high off the burner as I could get it. This summer I completed a 400 mile tour and did not pull my cables till I got home no burner problems. Average speed 30 to 35 MPH, I run straight unleaded gasoline at 120 PSI and the pilot at 30 PSI through a watts pressure reducing valve.
Your "two cents worth" are always far more valuable so thank you for your reply.
I remember when you told me about the Locomobile. Now that I have plumbed my steam automatic the right way around --to hold back raw, not vapourised fuel--it looks like I had better replumb the superheater coil to be nearest the fire and then have the vapourisors above it (they are the other way around at the moment). It will make taking off the burner plate much harder because the pilot and its vapourising tube have to come down with it but I will see what I can do.
I truly enjoyed your Grand canyon trip and Wright up.
On my EX I have the superheater mounted in a separate ring above the burner aud the vaporizer tube are as high as I could get them right under the superheater and not over any of the burner bars. Only the pilot.
The top side photo is of the casting pattern.
Edited 1 times. Last edit at 10/22/15 10:01AM by Rolly.
I am now reorganising the layers within teh burner space. I only have 2.75" of height between the burner and the bottom of the burner. Super heater was at the top but rarely superheated; it is 80" long.
The main vaporisor may be too long--see photo--it is 5' 6" but seemed to work well with refined kerosene and petrol, maybe because of the fuel flow, when it was half way up in the burner space. It was the pilot light vaporisor that clogged up after about two hours of running. As it has the smallest fuel flow and was nearest teh fire I am going to put it at the top and shorten it to run straight across the burner, on the line that the tape is in the photo. It will only be 12" long but has been getting orange hot just where it enters the pilot light; what do you think?
The superheating coil will now be 1 to 1.5" above the burner grate instead of 2.5" and when I measured the temperture in my viewing hole 1.5" above the fire it was 1060 C (1940F). Half and inch lower or higher was around 920C (1688 F).
That Grand Canyon trip was a memorable time, even with teh car not going too well, and the Flagstaff guys who helped us out were teh salt of the earth; we still keep in touch.
The new main fuel vaporisor is now 36" long,down from 66", higher up in the burner space (2" up from the burner) but curls over the pilot light near its exit to teh main jet and crosses the hottest, centre part of the burner.
We made it to Brighton from London on the Veteran car Run last Sunday...Yahooo!!!
Carrying on this thread abouyt fuels I can now say that I wouldn't recommend that anyone uses Shell V Power Petrol in a steam car pilot light; I have yet to fully assess its use in the main burner. The problem we had using it in the Toledo pilot, was that whatever was in it--which is not ethanol--produced a gluey deposit around the needle and up the venturi of the pilot. Consequently the gap around the needle in jet opening would block up and halt the fuel mix from flowing up the venturi. It could be cleared off the bowl and base with a blow torch and wire brush and teh venturi cleared with a pipe cleaner but it was a problem because the pilot would obviously have gone out by then. We got over it by cleaning every now and then but mainly by turning up the steam automatic so that the main burner flame rarely went out and we could hear its reassuring faint whistle most of the time.
The fuel mix was 75% Shell V power petrol and 25% Jet Kerosene. Not one blow back along the route.
More work to do with the steam automatic, main jet sizes, fuel mixes and teh length of teh superheating tube but thank you for all of the Forum suggestions to date, paticularly Rolly in the USA whose suggestions about the heights and lengths of the two vapourising coils and the superheater have had the most effect so far.