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Fuel Expansion Issues

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In this Tech Tip, John offers up a couple solutions to a somewhat common problem of fuel expansion on the older vehicles.

“I recently purchased your Two Plain 9 Super 7 Carbs, Offenhauser 1075 Dual Intake, 49-53 Ford V8. This kit has been installed on my 1950 Ford Coupe. Although the automobiles performance has been greatly improved I do have an issue. About 2 to 3 minutes after shut down fuel begins leaking from the throttle shaft of both carbs. I've recently added an Offenhauser Fuel Pressure Regulator which is currently set to 2.5psi (after starting out at 3psi) and still it leaks.  Any suggestions as to what I might try?”

Hi, thanks for the question. You inquired about the carbs leaking out the throttle shaft a few minutes after shut down. It sounds like the fuel is expanding and flooding over into the throttle bore.  This would be the first thing to check by making sure the float levels are correct.  The other thing that could be checked is the heat range of the carb and if need be you could install one or more of the phenolic spacers P/N 91011615.  Fuel pressure can be cut down to 2psi or slightly lower. Feel free to visit us on the web at or call 1-800-979-0122 with questions or to place an order.

  • John W.

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