Chrome Finish. By I feel lucky that this did not damage my generator because at one point I saw 30lbs of pressure while trying to start the generator. This experience ties with that the owner of a very early Twin Six Packard. . I am not going to quote all you said, but the flooding from the electric pump was caused by too much fuel pressure over coming the needle seat (or whatever kind of seat it has for the bowl) of the carburetor. Thanks again fellows, for such informative posts. . Find an Automotive Service Professional Holley 12-804 Fuel Pressure Regulator Brand: Holley 415 ratings -11% $6614 Was: $73.94 3/8" pipe thread ports 7/32" restriction Pressure ranges from 1 to 4 PSI Includes mounting bracket Satin finish See more product details + + Total price: $115.81 Add all three to Cart These items are shipped from and sold by different sellers. We tend to speak of pressure as higher or lower than atmospheric however it is a relative measure and pressure applies under all conditions. the cause for your fuel pressure fluxuation is because the fuel pressure is bumping up against the regulator and the extra fuel has no where to go , the quick fix is run a return line . I appreciate it. But, . Today's cars are all fuel injection so it doesn't matter how easily the gas evaporates, it is under pressure in a closed system from the tank to the intake. Steve, gasoline isn't a single chemical compound but a mixture of hundreds of individual chemical compounds which have a large range of boiling points. That work continues today through Holleys EFI products as well as through Holleys family of brands. Please try again. Copyright 2023, Antique Automobile Club of America. LOW PRESSURE REGULATOR 12-804 - Allstate Carburetor A small amount of IMCT in gasoline - depending on whether it is the winter or summer blend - depending on what that is as a fuel where you are - raises the boiling point like kerosene or diesel - but also raises or maintains the octane level slightly as ethyl acetate tends to loosen the hydrogen bonds and lets mixture burn more completely without causing pre-ignition we call "detonation" - which is really simply a slight lowering of the "autoignition temperature". They put everything they could into the coal oil including what we would consider low grade gasoline. Thanks to all contributors, particularly the information from Rusty, Bob and David. Of course you may already have this setup - that is the first issue. The only difference that the Holley tech told me between the two springs is the color. Learn more about our the fuel pressure gage needs to be in the line going to carbs. In a deadhead design the fuel comes into the regulator from the bottom past a check ball which is held open by a pin on the diaphragm. This is the complex world of Chemistry - which is far too complex to go into here. The pressure regulator works fine when mounted flat, but should work ok when mounted on it. Holley 12-804 Holley Fuel Pressure Regulators JEGS 41040 JEGS Fuel Pressure Gauges Now you need fittings. Some of these items ship sooner than the others. $41.19. Walk back over and looked again, 9lbs. if you run a holley blue pump it is set at 14psi from the factory and you must run the regulator that came with the pump . Does this mean that we are back to the situation described by OD where the lower boiling point additive reduces only the average boiling point? I have already been thinking about switching over to a modern fuel pump, say the Mallory 110, plumbing in a regulator just downstream of the carbs, and taking the bypass fuel back to the fuel tank. PDF Holley Billet Fuel Pressure Regulators P/N 12-841, 12-842, 12-845, 12 You could arrange them on a scale from naptha gas, gasoline, kerosene, stove oil, diesel fuel, light lubricating oil, heavy lubricating oil, grease, asphalt. Vapor lock is caused by usually a fuel that vaporizes too easily at too low a pressure (in the line) due to under-hood heat and not enough pressure on it - which would run great if it could make it to the combustion chamber first. These cars have the carburettor mounted in "V" of the engine with exhaust manifolds running along each side of the carburettor which combined with under hood engine heat makes these cars very susceptible to vapor lock. [endif]--> http://www.bp.com/liveassets/bp_internet/retail/retail_australia/STAGING/local_assets/downloads_pdfs/f/FN_modern_petro_vintage_engines.pdf,