The Holley 12-804 fuel pressure regulator features 3/8" NPT in/out ports. 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. When it burns however, it is an eye and throat irritant, even though it raises octane, burns hotter, easier, and cleaner. Thanks again fellows, for such informative posts. This product is made of high-quality materials to serve you for years to come. 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. Changing the vapor pressure (and thus the boiling point) of gasoline is not new. Browse In Stock and Ready to Ship Alternatives, Universal Fit, 1-4 Fuel Pressure Rating (psi), Aluminum. A: The reliable, albiet slower, stovebolts never suffered vapor lock because the fuel pump and lines were up front in the airstream of the engine fan. Shop Fuel Pressure Regulators at Summit Racing. 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. If youre looking to dial it in accurately its not going to do it. '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge . Product very good. In the fuel use map in the Exxon or Mobil gasoline websites, there are a few places where the Reid Vapor Pressure spec is varied from other fuels. It IS variable and a result of the various fuel blend components. [endif]-->. The first opportunity to try it occurred recently. There is clearance around the needle which I would have thought would be enough to vent the increased pressure but maybe not. Reviewed in the United States on June 5, 2022. All kinds of remedies were tried. No mention of vapor lock issues, but engine de-carbon activities. To keep it on simple terms, several people have confirmed that adding some kerosene, diesel fuel or stove oil will reduce the tendency to vapor lock and will NOT hurt an older model, low compression engine. By 1913 it was the other way around. 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. Will rise to above 180 degrees on the Temperature gauge. All Holley regulators are pre-set at the factory so there is no guesswork when first installing the regulator. 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. use a 1/16 - 1/8" restrictor in the end of your fuel line to see if you can set the pressure then. I look upon that effort with a heavy heart though, for I have been religious about keeping the old car original as possible. Much of the excess engine heat will end up soaking the fuel system under the hood. I will be trying one of these but am curious what is the active ingredient(s). What if any additives would do this and why? Could you explain a little more about how you would run the bypass? Add to cart. The intent being to get "cool" fuel to the carburettor bypassing the areas where the system heats the fuel. To avoid extra back pressure on the pump, and to keep cool fuel flow past the lowest pressure point in the fuel system; a by-pass line should be used and it should NOT "dead head" to the carburetor - that is put the return line as close to the carburetor inlet as possible. => https://www.holley.com/data/Products/Technical/199R7914-3rev3.pdf. Carb Part, 14 PSI Fuel Pressure Regulator Set 3/8in NPT Port 12804 for Holley : Amazon.com.au: Automotive CALIFORNIA WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov. The 12-804 is made from durable aluminum and has a satin chrome finish that is extremely resilient to corrosion and abrasive chemicals. 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. Mr. Gasket 1561 Fuel Pressure Gauge 1.500 in. [endif]-->