It appears this one needs 40 to 50 minimum. The other part numbers utilize an AN O-ring inlet, outlet, & return ports, and do not require any sealer on the threads. . Can i install a fuel pressure guage on the unit itself? ***The inlet pressure limitation is 7 psi. Spring clothes pins, aluminium foil, wet burlap, etc. Going to check my VW bus fuel pump pressure. We will have the previous answer corrected. The higher the RVP, the greater the tendency to vaporize or vapor lock. [endif]-->. You'll find they both have the same initial boiling point - been there and done it. A: Turn the screw out to lower the pressure. Holley 12-804 low pressure regulator, Weber, jeep etc. It is an experimental thing and MORE IS NOT BETTER - less is better until you find the happy medium based the fuel you buy or have in the tank already. This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles. Any of these heavier than gasoline petroleum distillates above will raise the vapor point of gasoline if mixed into it. Many thanks for taking the time to clarify this interesting subject . Shipping cost, delivery date, and order total (including tax) shown at checkout. The unit however is working fine but am curious about the missing gaskets and how important they are? Please try again. I commented that it was already vented by the clearance around where the float needle projects through the top but he advised that this was not enough and the vent needed to be at least a 1/4" tube and that he could see it venting vapor. Loosening the regulator locknut and turning the adjustment screw clockwise increases the pressure. I can start my car instantly after sitting in a cool garage at about 75 deg F. Drive 30 miles and then park for 20 minutes. Fuel pressure regulator includes mounting bracket with 2 each self-tapping screws for regulator to bracket installation purposes and 3 screws for bracket to vehicle installation.Regulator has a 3/8" NPT . If you put in too much you can return the fuel to some "kick" without knock with a small amount of acetone. It will meet your needs and deliver great quality at an affordable cost. I got all of my supplies in the Home Depot fittings section. It's easy! Contact Us - DO NOT EMAIL CAR QUESTIONS. Lots of Chinese Holley 12-803, 804 etc knock-offs are available. P/N 12-803, 12-803BP, & 12-804 Installation Instructions 199R7914-3 NOTE: 12-803BP IS NOT TO BE USED WITH MECHANICAL FUEL PUMPS! Unfortunately, this fuel pressure regulator does not even come close to regulating the pressure and keeping the pressure down. In theory the vapor carburetor was the way to go in that day - with lower flash point fuels like poor grade fuels that all pretty much resembled the weight of kerosene in that early day of motor fuels. We encountered an error while updating this page. 10 in stock. [endif]--> http://www.bp.com/liveassets/bp_internet/retail/retail_australia/STAGING/local_assets/downloads_pdfs/f/FN_modern_petro_vintage_engines.pdf,