Today I completed the installation of the temperature controller for the carburetor cooling fan. I used Velcro to mount it underneath dash. It’s a neat little temperature controller although not much for looks it has up to a 30° temperature differential, minus zero something up to a 200° temperature range, a 10 amp load so I probably won’t need an external relay to run the fan and an on/off switch for when it’s not in use. I wired it directly to the 12v terminal post (that the amp gauge is on the fuse box), I used an in line fuse holder with a 3 amp fuse. Right now I’m just monitoring temperatures of the carburetor float bowl under normal driving conditions. I mounted temperature probe right underneath the fuel inlet and temporarily taped to the float bowl using insulated tape (see pic) after I get the header and heat shield installed I’ll use a clear silicone and insulate it. I can easily remove the controller or mount it elsewhere but for now it’s easily visible. I want to compare my recorded temperatures now and after I install my wrapped stainless steel header, heat shield and cooling fan. What I’ve noticed so far is that just raising the hood changes things quite a bit. I know I won’t be able to cool down the carburetor like a little refrigeration unit so my hope is in using a axial fan over a well made heat barrier shield (DEI #010517) that I plan on mounting to 4 bolts mounted to the bottom of the intake manifold (the length of the cylinder head) then I will be able to simulate something close to opening the hood at a minimum. I’m going to mount the carburetor to titanium studs using stainless nuts and lock washers, of course the phenolic spacer. My only procrastination point is weather or not to use the new stainless steel OGTS stock heat shield I have ported to my carburetor or the aluminum spacer to allow for easy access to the manifold bolts. That will complete the first phase. So today here’s what I observed. I’m going to have a 2-4 week period until I can install the rest so am going to record temperature changes under different driving conditions and ambient temperatures. I also need to decide how much air movement is needed to make enough of a difference when the cars not moving, the 3 choices I’m looking at are 60, 100 or 200 CFM axial fans.
Here’s what I observed today for the carburetor bowl temperatures:.
70° ambient temperature (temperature display shown on carburetor matched ambient on a cold start)
90° during downhill drive
110° during uphill drive and shut down, H2O is at 180°at shut down
140° after 10 minutes (boils in the mid 130’s) smell is very present at this time
142° after 15 minutes
143° after 20 minutes
143° after 25 minutes
143° after 30minutes
Lifted hood temperature dropped to 137° in a couple of minutes then closed it
133° after 45 minutes.
Peak heat soak after 20 minutes
Only 70° outside we could be still running Winter gas with its higher RVP value (who knows)? I’ve read that the gas companies use more butane in winter for easier cold starts and to keep costs down on the octane boost. I thought summer gas was out early but I guess not, by Memorial Day it’s supposed to be out for sure, much less of those volatile additives will be in our gas then, the last time I checked summer pump gas the actual fuel in my carburetor bowl it was at a full boil 30° higher, around 165°. I’m going to also measure the actual liquid boiling point using a temperature probe in the liquid because there’s bound to be a discrepancy between it and the temperature reading measured on the outside of the float bowl. I haven’t done that yet I’ll see by how much. Insulating the fuel lines and adding a return line are the final steps (if needed). One last thing worth mentioning I’m using the box air filter on top of the Weber, it allows me to access a lot of air right from the front. I want the cooling fan to have as much cool air as it wants for now. Gil’s recommendation is to use the Redline snorkel kit and grab my cool air from the hood louvers it’s a good suggestion from someone who’s tried it all for sure, I can see doing that down the road, if I can cool down the fuel and bring cooler air in that is as good as it gets. I can’t think of anything I possibly left out. Anyone care to weigh in?