A little background: Friend bought a pretty nice '67 L71 several years ago and shortly after the fuel pump failed, showing an external leak. He bought a replacement, supposedly correct AC Delco from the guy on the west coast who's usually the highest on all his stuff, paying over $400. Put it on the car and it wouldn't idle or hot start, so he sent it to a mechanic where he lived. He told me the mechanic was waiting for an adapter to check the fuel pressure, to which I said he's wasting his time and your money. So the test showed the pump was putting out 9 lbs. (so much for MY opinion). I bought a '66 L79 Nova a couple of years ago with similar scenario. New pump and car was miserable to drive. Shuts off at red lights, cranks all blubbery puffing smoke. So I put a gauge in the line and it's showing just below 9 lbs. I hated to put something non original on this car, but bought a Holley inline, NO return line regulator and plumbed it right into the side of the mechanical pump so it's not so noticeable, set it to 5.5 lbs and it made absolutely a new car out of it. It actually acts much better than even before the pump failed. I have multiple L71 cars of my own and have always thought they were ornery. Holley's in house shop has built one set of my carbs and a vendor that I've used for years has done others and the result is the same. My '67 that I drive more than the others has been especially bad lately, not wanting to idle and hard starting when hot. So I put a gauge on it tonight and it's showing 8.5 lbs. I believe that many of the people on the internet that are complaining of vapor lock and other similar issues as well as just simple tuning with flat spots, inconsistent idle speeds, etc are actually experiencing high fuel pressure which seems to be a major problem with not only no brand parts house pumps but also AC Delco replacements. I'm going to (RELUCTANTLY) butcher a fuel line on my '67 and put another inline regulator in it but there are obviously tons of correctly restored cars without regulators added and I'm wondering how many other people experience similar problems and how they're dealing with it. I do not believe that Holley carbs like anything above 6 lbs.
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