Long story for another day, but I'm shaking down a nice 1940 Deluxe for someone else (although as a mechanical-brakes-and-gravity-fed-banger guy I am wholly unqualified for the job), and have run into some fuel related problems. I drove the car a good bit today, and as I pulled out back onto the main streets, the car started bucking hard (after about 5 minutes of idling outside of a family member's house) and then died at idle. I found that the neoprene fuel line was scalding hot from the carb all the way as far as I could get to in the engine bay, and the inline Offenhauser-style pressure regulator was also extremely hot to the point that it would burn. The car has an aftermarket coolant gauge, and it was only about 180 at the time this happened. I confirmed the gas cap venting was working, let the car cool off for about 10 minutes, and then started her up and drove a few miles back home and she ran like a top. On what may be a related note, I suspect that the fuel pump mounted over the rear crossmember is tired, exacerbated by the hot climate down here. When I kick it on starting cold, I can usually hear it with the window rolled down. When starting again right after things are up to temp, I have to physically put my hand on it to feel it vibrating a little. I cleaned off the ground to the crossmember and that seemed to help, but I still encounter these weird starting problems from time to time. More to the point, the pump occasionally also gets notably hot to the touch, and I suspect there is some internal resistance going to ground which is causing the heat. I'm planning to replace the pump with a quality unit, and I will probably order a couple phenolic spacers for the two 94s, but that still doesn't really answer my question of why the fuel is so hot so far down the fuel line. Any suggestions of things I can check/look at? Here's some photos of the engine, and the fuel line routing. You can see the inline fuel pressure regulator just upstream of the fuel log.
That reg is garbage...IMHO. You may be pushing too much fuel p*** the needle /seat. Whenever I work on a friend's car, that round dial regulator is the first thing to go in the can. I use a Holley 12-804 dialed at just under 3 pounds on my flatty.
Bandit Billy is not wrong. I'm surprised you can get the car to run with that regulator! I've never seen a more inconsistent regulator in my life! Back to your hot fuel line question... how close is the exhaust to any part of the fuel system? Is the exhaust preheating the fuel at the tank itself? I know LV can get hot AF... are you certain the tank is not just absorbing the heat from the pavement? 3blap.
You should probably give the regulator Bruce Lancaster’s “floatation test”. Throw it in the nearest lake, and if it floats it’s no good.
If you’re running rubber lines clear back to the tank, they could be expanding from old age and Nevada heat. Change your fuel filter and change over to steel lines. Usually an electric pump will prevent fuel heat issues on an engine. I’d put a gauge on it to see if it’s providing constant pressure to the regulator.
Is there any clearance between the front carburetor feed line and the radiator hose? Check to see if any fuel lines are close to the exhaust system. If they are reroute them to give them more space so the heat from the exhaust doesn't heat the fuel lines up. Flat head engines tend to run hot by design. Check engine temperature.
You have a ton of room under there, I like your idea to add a couple phenolic spacers under those carbs (the thicker the better). Don't forget to order longer studs if necessary.
You mention that the electric pump is mounted on a crossmember. Is the pump mounted higher than the fuel level in the tank? Could the pump be laboring to try pulling fuel up to its level? Could the pump be overheating from the additional strain? Or maybe the pump is on its way to failing anyhow. Would the pump be transferring some of this heat to the fuel as it moves thru the pump? Maybe check how many amps the pump is drawing after it runs for a while.
block off the heat riser , make some thin tin pieces like come this a set of SB chev gaskets and put em in there ,, and use a quality regulator ,, fabricator john miss you dad
If wanting to diagnose issue one change @ time .. 1st "definitely" remove that style fuel pressure regulator like others have said. Test & add the cross over heat blockers. Then still issue move to Checking fuel pump , lines routing from fuel tank to fire wall ..
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