It takes a lot to hurt today's stainless steel valves, but in an older car be careful - and an exhaust gas temperature gauge is not a bad idea to invest in. The '54 Bentley already has an electric SU pump back near the tank, and it's low pressure output is just about right for the two SU H6 type carbs. near you All petroleum distillates have different chemical properties which change depending on what you mix them with. This satin finish regulator feature 3/8 pipe thread . I now think that what was happening was that there was sufficient heat in the carburettor to boil the fuel, the vapor from the boiling increased the pressure above the float preventing it from rising and shutting off the supply. See also Tom Ogle's "modern" vapor fueling system - google it. ***The inlet pressure limitation is 7 psi. All Holley regulators are pre-set at the factory so there is no guesswork when first installing the regulator. Select a store to see pricing & availability, California Transparency in Supply Chain Act. Q: THE SECOND ISSUE - the vapor system on the Packard is going to be a problem no matter what today. Brief content visible, double tap to read full content. The peak was reached in the sixties when heavily leaded gas of over 100 octane was available. Holley low pressure reg woes #12-804. One needs to have studied Chemistry as I have to actually know how this works. Most regulators need to be flowing to set pressure. Now my equipment sits idle while I wait for a response from the vendor. You can do a Google search for it, though. Some Holley 12-803 4.5-9 psi and 12-804 1-4 psi regulators mislabeled from factory. Volatility is a measure of the gasolines tendency to vaporize under a given set of conditions. Fuel pressure regulators are used to adjust for fuel pressure requirements of various carburetors. I switched on the electric pump and it instantly picked up and ran for a few seconds then reverted to the classic vapor lock symptoms. It needed a bit of adjusting for my purpose, but other than that, it performed perfectly. The regulator is a Holley 12-804, I was told it went down to 1 psi and I have a stock mechanical fuel pump. LOW PRESSURE REGULATOR 12-804 quantity. . As you can see from what it replaces - it is "hot" solvent - but not quite as hot as acetone in its ability to dissolve other things. Talk to the experts. It is no different than mixing water with ethylene glycol to make what we call anti freeze or with methanol to make windshield washer fluid - you get a completely different product - it is not just water any more; and nor can you separate them back into their original separate entities - so you cannot think of them that way any more either. Typically there are "winter" and "summer" blends with different vapor pressures to promote atomization at cold temps and to discourage vapor lock at hot temps. Somewhat of an inconvenience but that's why it's probably cheaper than other places selling the same part number. We tend to speak of pressure as higher or lower than atmospheric however it is a relative measure and pressure applies under all conditions. Shipping was fairly fast. It's unlikely that anything's stuck. bowls after each run, just to see exactly at what temperature the problems become apparent. Overview. Designed using state-of-the-art technology and with customers in mind. 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. fuel pressure in at the top, fuel pressure out on each side. . There is supposed to a marking on the spring with the correct color, red or gold if it is the low pressure spring. Copyright 2008-2023 OReilly The only difference that the Holley tech told me between the two springs is the color. My plan was to install a fuel pressure regulator on the line going to the generator so that the bypass valve needs less fine tuning to maintain the same pressure in all temperatures. Never tried it with my old Model A Ford but I heard that they will actually run on Kerosene.. Conversely if you go too high and it knocks - you can bring it down with kerosene or the paint thinner family. However the part number on the box was 12-804 which should be a 1-4 psi regulator BUT the Part number etched on the unit was 12-804 4.5-9 psi which doesnt exist. ***The inlet pressure limitation is 7 psi. There was a problem adding this item to Cart. Though I once has it working with only two 0-140 regulators, and since I had messed with the 0-140 regulator on the carb feed side trying to get it to work previously - it popped up to 50 psi - but the 15 psi reg held at 9 psi to the carb - for about 5 minutes, until I tried to reduce the 0-140 below 50 psi. This item can be returned in its original condition for a full refund or replacement within 30 days of receipt. (that is this one in the image below) The adjustment spring under the adjustment screw is pushing down on the diaphragm holding the ball off it's . As Raywith pointed out, you need to let the pressure go somewhere. In some areas, according to the map, RVP can vary from about 7.0 to 9.0 in some of the fuels. Works, don't use a liquid filled gauge in an engine compartment! The term heavy ends may be old fashioned and obsolete. Most certainly also, should that be successful, I will then experiment with IMCT as well. Adding heavier weight hydrocarbons WILL raise the vapor point under pressure - usually enough to keep the fuel from vaporizing in the line or boiling off in the carburetor bowl while flowing. Fuel Pressure Regulator; Holley fuel pressure regulators are designed to precisely control the fuel pressure from the fuel pump to the carburetor. Shop Fuel Pressure Regulators at Summit Racing. Once the fuel fills up the float bowls in the carburetor and the needles and seats shut, it starts to build pressure, pushing the diaphragm against the adjustment spring under the adjustment screw and allowing the ball to go "up" against the seat, effectively shutting off fuel flow to the carb. 12-804 12-500 Low-Pressure Fuel Regulator (std. In those days before 1905 kerosene had a strong piercing odor and coal oil lamps sometimes exploded. A vapor lock condition would be caused. I am having problems understanding why you say OD is wrong and Rusty is correct, it seems to me you are all saying much the same and that is that gasoline is made up of many components each having different boiling points and the components with the lowest boiling point are the cause of vapour lock. From propelling the LS-, Coyote-, and Gen 3 Hemi-swap trends, to continuously innovating late-model and vintage vehicle performance, Holleys commitment to its customers and their cars is at the core of everything we do. But the heavier elements will raise the boiling point of the mixture. I have a electric pump at the tank to try and speed up the fuel cooling process but if you have a 100 deg F day you may have fuel near 100 deg F in the tank. Holley HOL 12-804 12-804 Fuel Pressure Regulator; ; Customer reviews . should be one inlet in two outlets out, i've seen very smart mechanically inclined people hook the carb to one outlet and the pressure in to the other, it's easy to do, not saying anything bad but could be a a possibility. Chemistry does NOT work that way - just like adding more any one ingredient to a cake mix will make the cake better. IMCT is found in the paint isle of any hardware or home improvement store usually in quart or gallon cans. P/N 12-803, 12-501, 12-804, 12-500, & 15812NOS Installation Instructions WARNING! Of course you may already have this setup - that is the first issue. Take a look at the article below. How much should I add to every gallon of gas.I believe they are adding about 5% ethanol to the fuel here. The two will be very close to the same just as would Water and Anti-Freeze boiled in an open pot. I have the one I have set up in a deadhead setup. te4cmCbGnt]&~`N@RPyBTa$=~fo:/T 92YE)3Uofo4Ou].-zowDt*ae^qf9z/?. For now, in 70 degrees ambient, the bowls are 100 F. at shut-down and after 15 minutes they rise to 115 F. At these temperatures the engine starts back up fine, but I believe another ten degrees will be in the problem zone. [endif]--> Many thanks for taking the time to clarify this interesting subject . ${cardName} not available for the seller you chose. I realize this is an old post - but when people write things that are WRONG - it leaves the next Joe who comes along thinking that is the correct answer when especially in this case - it is NOT. Troubleshooting Carburetor Problems and Vaporlock Blues Revisited - Hagerty Lifestyle. Holley fuel pressure regulators are designed to precisely control the fuel pressure from the fuel pump to the carburetor. http://www.frontieroil.com/attachments/contentmanagers/106/PrdctsSpec_UnleadGasSpecs.pdf. Powered by Invision Community, http://www.bp.com/liveassets/bp_internet/retail/retail_australia/STAGING/local_assets/downloads_pdfs/f/FN_modern_petro_vintage_engines.pdf. The vapor lock issues that I have are with 1920's Packards where the fuel system is essentially at atmospheric pressure throughout. . No issues. So this thread has been a great find for me particularly at this time. The BP article does not address how to re-blend your own fuel, and indeed - each batch of gasoline - and even how long it has been sitting in a tank will change it's properties as certain things evaporate out of the fuel changing it's properties if in a vented tank. The chemistry class experiment you are referring to will yield the approximate boiling (vapor) point at STP - Standard Temperature and Pressure ONLY. The thinner, lighter products are at the light end of the scale the thicker heavier products are at heavy end. Holley Fuel Pressure Regulators 12-803 HLY-12-803. $41.19. Holley part number for the kit is 12-807; Summit sells it for about $6. There's always a catch with bargains, Reviewed in the United States on July 9, 2022. I suspect as the article suggests even with all these steps you can still get the crap gas to boil if it is hot enough under the hood. Shopping Cart I have found IMCT is a happy medium that does both in the right quantities - raise boiling point and octane just enough to be a "goldie-locks" kind of additive to help prevent vapor lock. [endif]-->. here's one installed,same holley low pressure regulator, line pressure in the top, one side is hooked to the fuel pressure sender, other to the line going to the fuel block.