Purchased the regulator from Baxter, unit arrived in 4 days.. Carb Part, 14 PSI Fuel Pressure Regulator Set 3/8in NPT Port 12804 for Holley : Amazon.com.au: Automotive Did not like having to reset to zerobut I did. So if you're looking for a FPR to get 1-4 psi, then the 12-804 is no longer your best choice. He asked about issues and thoughts of what causes vapor lock, so it is just answered in more detail and suggested solutions on how to fix vapor lock. I cannot help you - and no one can without knowing the exact make up of the gasoline being refined where you are. Then, we got what was loosely described as winter gas, all year round, with RFG. I have adjusted a 6-9 lbs pump down. Product very good. If the carbs are drawing fuel and you lower the pressure at the reg, it should show on the gauge. Please choose a different delivery location. 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. This item can be returned in its original condition for a full refund or replacement within 30 days of receipt. A larger tank might need two quarts. All Holley regulators are pre-set at the factory so there is no guesswork when first installing the regulator. Reviewed in the United States on June 5, 2022. These will raise the boiling point of the fuel but reduce the octane. Part #: 12-807. . The project involved installing a 250LPH electric fuel pump on a relay system and then T off to a bypass line and a fuel pressure regulator on the fuel line going to the generator. 3/8 Inch NPT Ports 1 Inch 2 Out. By the way, I had an excellent service from this seller (5 stars!). You may receive a partial or no refund on used, damaged or materially different returns. P/N 12-803, 12-803BP, & 12-804 Installation Instructions 199R7914-3 NOTE: 12-803BP IS NOT TO BE USED WITH MECHANICAL FUEL PUMPS! I found this document on my local Oil Refinery's web site and it may help explain some of the problems with vapor lock and hard start. Thanks again fellows, for such informative posts. I would welcome your advice on this - with apologies for the length of this post. Chemistry does NOT work that way - just like adding more any one ingredient to a cake mix will make the cake better. The Holley 12-804 fuel pressure regulator features 3/8" NPT in/out ports. Stay up to date with the latest releases, events, promotions and more. 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. If your having pressure controll issues with the Holley regulators you can eliminate most problems with stability by installing a by pass line back to the tank and usualy a street car can use 1/8 copper. ${cardName} unavailable for quantities greater than ${maxQuantity}. on this design the adjusting screw all the way out should decrease the pressure the most - IF the ball valve will seat TIGHT, When I adjusted pressure below 30 - it would not seat any longer even with the adjustment screw all the way out. Most regulators need to be flowing to set pressure. I do wish there were some stamped values on the adjustment screw like other models I have seen. Use with standard pump only -not recommended for maximum pressure pumps. The owner had tried all practical means to reduce the heat gain of the fuel system but with little improvement. 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. Recommended Parts. Holley 12-804 low pressure regulator, Weber, jeep etc. 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". A by-pass style regulator has the fuel coming in the same side of the check ball as where the fuel comes out to the carb. As Raywith pointed out, you need to let the pressure go somewhere. Wouldn't the water still evaporate at the same temp? Holley 12-840 4.5-9 PSI Adjustable Billet Fuel Pressure Regulator with 3/8" NTP Ports,Black Anodized Brand: Holley 24 ratings | 11 answered questions $10902 & FREE Returns The package length is 9.652 centimeters The package height is 6.604 centimeters The package width is 9.144 centimeters Package Weight : 0.2 pounds See more product details This product is universal and applies to all vehicles. He finally achieved significant improvement by fitting a vent to the carburettor top (which is routed away and under the car for safety). 2023 Holley Performance Products, Inc. All Rights Reserved. Neither the Holley instructions nor anywhere I can find says what the maximum inlet PSI should be allowed to the regulator - but I was told it was 16 psi and one other spot on the web says something similar. 10 in stock. store ${cardName} not available for the seller you chose. [{"displayPrice":"$58.17","priceAmount":58.17,"currencySymbol":"$","integerValue":"58","decimalSeparator":".","fractionalValue":"17","symbolPosition":"left","hasSpace":false,"showFractionalPartIfEmpty":true,"offerListingId":"UhTnfcw7IZxaNntXlJwDKCZdMn2swwW9Qa8PxzrWBz%2By8RC0ilxVsHIj8toGUO%2FPmmF8b2HD1iNYooZ7n4ER0XuKiQsQQvJG86lgqsni6KYZs%2FdLcIOIE0Ukulbz%2BJYBuUOC820ciUZxU2UEL9sUjtoq8gdk8bOPIZ3QChg8zpgyIZxlTaXQEA%3D%3D","locale":"en-US","buyingOptionType":"NEW"}]. . Most certainly also, should that be successful, I will then experiment with IMCT as well. NPT Inlet Attachment: . The summer gasoline vaporizes in the line and the heat soak is quicker and longer on hot day's. You need to be a member in order to leave a comment. Somewhat of an inconvenience but that's why it's probably cheaper than other places selling the same part Great product from holley, but these do not come with the supplied tap that's suppose to be in box for the 2 machine screws that mount the regulator to the bracket. Refineries have been doing this for decades. Holley HOL 12-804 12-804 Fuel Pressure Regulator; ; Customer reviews . the fuel pressure gage needs to be in the line going to carbs. (Maybe this arrangement was intentional to assist in vaporising the fuels of the day but it is all bad in hot weather with today's fuels). Please try again. . The two will be very close to the same just as would Water and Anti-Freeze boiled in an open pot. The float has a needle that projects through the top of the carburettor so it is possible to see whether the float is "floating" or not. I do not have a pressure regulating valve to reduce the pressure from the pump but it works fine with no flooding under normal conditions and I have fitted a modern soft seat to the float cut off needle. It is not intended to be sold or used for any other purpose. Sorry, you're using a web browser that is no longer supported. This Holley FPR (12-804) use to be a perfect choice to solve the "too much fuel pressure" produced by the aftermarket fuel pumps on vintage VW. I turned into a side street and opened the hood. TURNING THE ADJUSTMENT SCREW ALL THE WAY IN WILL RESULT IN EXCESSIVE FUEL PRESSURE . Shopping Cart For over a century Holley has driven the cutting edge of fuel-system design. 12-804 Part Type: Fuel Pressure Regulators Product Line: Holley Fuel Pressure Regulators Summit Racing Part Number: HLY-12-804 UPC: 090127020234 Regulator Pressure (psi): 1-4 Regulator Style: Non-return Regulator Location: Inline Boost/Vacuum Reference Port: No Gauge Port: No Inlet Quantity: 1 Regulator Inlet Size: 3/8 in. 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. I have largely eliminated this problem with all fuel system components rebuilt, and an electric fuel pump but will get occasional stumble with a hot (after say, an hour run) engine idling or in traffic if it is say, 80 or hotter out. The higher the RVP, the greater the tendency to vaporize or vapor lock. Lots of Chinese Holley 12-803, 804 etc knock-offs are available. I remember when I was a teen in the 50's and everyone had a flathead Ford V8 or a Chevy stovebolt 6. The regulator is a Holley 12-804, I was told it went down to 1 psi and I have a stock mechanical fuel pump. . Second, you adjust this regulator by turning the hex screw on top - does anyone happen to know how many pounds one or more full turns would produce etc? . Each Holley fuel pressure regulator is fully adjustable so regulating the fuel pressure to your engines needs is a simple task. [endif]--> http://www.bp.com/liveassets/bp_internet/retail/retail_australia/STAGING/local_assets/downloads_pdfs/f/FN_modern_petro_vintage_engines.pdf,