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I have a Holley throttle body...somewhere. You'll maybe get answers from someone else before I can dig it up and see why the OEM plumbing doesn't work.
Seems suspicious, given that the Holley was intended to be a direct replacement. You ARE removing the fuel fittings from the original throttle body, for re-use on the Holley...right?
The Holley TBI unit (the pressure regulator) is threaded for fuel inlet and fuel return exactly like the Rochester TBI. Screw in the adapter fittings (with fresh plastic gaskets) from the Rochester, the fuel hoses (with fresh O-rings) screw into the adapter fittings.
The one complication is that the adapter fitting for the fuel return hose has mild interference with a vacuum nipple on the rear of the throttle body. Some gentle prying, or perhaps a little grinding of the corners of the hex used to wrench the thing into place would fix that.
Photos below.
Last edited by Schurkey; Feb 28, 2020 at 02:40 AM.
The bare ports at the rear of the Holley TBI. Larger (Left side in photo) is inlet, smaller (Right side in photo) is outlet.
With the Rochester fuel fittings taken from the original TBI unit. Remember, these fittings seal to the Holley fuel pressure regulator with plastic gaskets. Note lack of clearance between vacuum nipple and corner of fuel adapter. Shouldn't be a big problem to crank the adapter in, especially if the corners were ground-down a little.
Viewed from the top of the TBI. Adapters stick out the rear, pointed somewhat downward.
The original fuel tubes are sealed with an O-ring. There are also fittings available in the aftermarket that adapt the metric thread/O-ring seal to 37-degree SAE flare, for use with so-called "AN" hose ends. (They're not really AN, which is an obsolete Military spec.)
Last edited by Schurkey; Feb 28, 2020 at 02:37 AM.
