Too much fuel pressure for a given needle and seat assembly can overload the needle and seat and may cause flooding or drivability problems. I tried to bring the 0-140 pressure feed regulator down to 30 by adjusting the two - to up the return flow and lower the feed pressure - but the 15 psi reg I had just worked on started to climb past 9. How much should I add to every gallon of gas.I believe they are adding about 5% ethanol to the fuel here. Bobburns thank you for the confirmation and technical explanation. http://www.jalopyjournal.com/forum/showthread.php?t=386155, Kingman, Arizona - The place on the way to other p, http://www.holley.com/types/Fuel%20Pressure%20Regulators%20-%20Carbureted.asp, (You must log in or sign up to reply here. Purchased the regulator from Baxter, unit arrived in 4 days.. If you purchased April gas when you take your Antique out of winter storage it is only a month until the switch from 124 deg F to 140 deg F. This might explain a lot of problems in early summer. It seemed to work fine for a while after I dialed it into 2psi at idle, but now it reads 6psi and it won't adjust down to 3psi. Q: 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. 9 really is max. $12.15: ac000400: Front Axle Beam Bushing Reamer For 1.34 Up To 1.50 Diameter . Joined: Apr 7, 2008 Posts: 1,727. Depending on what kind of electric fuel pump you used you will need a regulator - or series of regulators to step down the pressure getting to the carburetor like a Holley 12-803 type at the very least. He finally achieved significant improvement by fitting a vent to the carburettor top (which is routed away and under the car for safety). 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. The pressure regulator works fine when mounted flat, but should work ok when mounted on it. If yes what size should I, A: The lower I can get with this pressure is 3.5 psi (at max adjustment). If youre looking to dial it in accurately its not going to do it. The reg takes 3/8" fittings and the gauge takes 1/8" fittings. To ensure this condition, the installation of a Holley 12-810 oil pressure safety switch is recommended 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. Add some heavy ends. Recommended Parts. 12-804 : Quantity: Share : . . The carburettor was flooding, the electric pump was still running. 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. A vapor lock condition would be caused. This diaphragm repair kit is for 12-803 and 12-804 regulators. Holley part number for the kit is 12-807; Summit sells it for about $6. Eligible for Return, Refund or Replacement within 30 days of receipt. For more information go to www.P65Warnings.ca.gov, WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov, WARNING: This product can expose you to chemicals including 1,1,1,2-Tetrachloroethane which is known to the State of California to cause cancer. Does it come with the hose fittings or to be bought separately? [endif]--> http://www.bp.com/liveassets/bp_internet/retail/retail_australia/STAGING/local_assets/downloads_pdfs/f/FN_modern_petro_vintage_engines.pdf, ,