Re: Cruban pilot
Posted by: EBG
Date: March 22, 2015 03:08AM
I used a Cruban pilot for a number of years on my car. When I got it, the original cast external vaporizer tube that wrapped around the outside of the front of the pilot had been replaced with tubing, probably because the original casting had cracked. This was nicely made and worked OK, seemed to like gas (unleaded or white) worked better than Kerosese, although once hot it became unreliable and would start burning under the "grate". This was a persistent issue, the main burner would kick in, the pilot would go out, but it would, almost all of the time, relight as soon as the burner shut down. Although, as I say, once things got hot it would eventually light below the grate. I would turn the pilot off, and relight once it was a bit cooled down, and it would burn great again, at least until the burner came back on. I spent some time really making sure the pilot burner intake was clear and unrestricted, played with jet sizes and fuel pressure, etc. Got to the point where I would have a nice burning blue flame hot pilot (about 4-5 psi) on gas, but it would always go out when the main burner lit, and relight when the burner shut down. It would still light the main burner even when it was burning below the "grate", so I could live with it, but it bugged me. I aways figred the pressure in the burner area just got so high when the main fire came on, that it blew the pilot out, it only relit once the pressure in the burner area reduced as the main fire started to shut down.
At the end I tried bypassing all the vaporiser that is in the pilot casting, and rigged a vaporiser and jet from an MSR camp stove, wrapping it around the exterior vaporizer heating area. This worked OK, although I had to do more preheating with the torch to make sure the shorter vaporiser was really hot before I lit it. Sometimes, if I was not careful, or tried to push things too fast, it would stop vaporizing the fuel and the pilot would go out and flood with unburnt fuel. This was not an issue once the main burner lit and everything started to get hotter. I did still have the problem with the pilot going out when the main fire lit. I tried adjusting the jet size and the pressure, hoping that with a smaller jet, I could increase the pressure and not have the pilot blow out. However, I could never get the pilot to burn with a nice blue flame across the entire burner area with a small jet and a high pressure, 4-5 psi always seemed to yeild the best flame. I don't remember off hand what jet size I ended up using, just know it was pretty small (70s drill size). In the end I could do an entire day of tourning without the pilot going out and not relighting the main fire, but, after it warmed up it always would relight below the "grate" with a sooty yellow flame.
I now have a Maxwell pilot, that, knock on wood, is burning just fine, although I don't now have any kind of peep hole to see if it stays lit when the main is on.
Hope this helps some, and please let me know if you work this out.