66 Holley Carb Question

[William G.]

My recently acquired 66 Roadster L79 350 hp with all original driveline has a Holley carb 4160 List 3367. The former owner had the carb rebuilt by Holley a few years back and says it was original to the car. I have two questions:
1. The carb has a stamped date 661 which corresponds to the first week of June 1966. The engine build date is 27 May 1966 and the final car assembly date was about 8 June 1966. Can this be the original carb with the date a week after the engine assembly date and a few days before final car assembly?
2. The carb is running extremely rich and the plugs are black,dry and sooty. Has any one had any trouble with Holley rebuilds as far as incorrect jets or a similar problem to this?The car runs smoothly but without full power. The former owner states that this is the way he received the carb from the factory rebuild. Thanks for any help.

[Kevin M.]

Re: 66 Holley Carb Question

Engines were built without carbs, I can see this date working. Next most people here don't have Holley rebuild there carbs so responses will be more of what's wrong and how to fix it, I don't know. This picture below is from John Hinkley showing the engine test run process, he said they put oil, coolant ran for less than a minute or something like that and them dumped the fluids and sent it down the line.

Kevin

[Jim T.]

Re: 66 Holley Carb Question

Bill reference the previous owner telling you your 66's carb was rebuilt by Holley a few years back. Holley started putting a modification on later carbs that would help prevent destruction of the power valve if the engine back fired through the carb. Your carb may not have this modificaton when they rebuilt it. Anyway your rich condition is probably a ruptured/blown power valve. I have had more than one occurrence with my 68 L79 since I put a Holley on it in 1973. A proven detection method I have used, release the hood, start the car, remove the air cleaner lid. Put a finger over the front vertical vent. If the engine dies right away, this indicates the power valve is ruptured. If the power valve is good the engine will not die right away, but will eventually die if your finger is held in positon obstucting the vent. Power valves are easy to replace. You can check the jet size when you replace the power valve, the size is stamped on each jet in the metering block. You can also remove your carb and using parts from Holley and install the modification to help prevent the infamous Holley ruptured/blown power valve. Holley power valves are available separately as well as the vent bowl and metering block gaskets. I have found them at Auto Zone. The "65" power valve should work for your engine.

[William G.]

Re: 66 Holley Carb Question

Thanks to both Kevin and Jim for their responses. I'm happy to hear that the carb could be the original. As far as the carb running rich, I have read that the power valve is a problem as well as even the jets and the float. But thanks to Jim I have a simple test to determine if the power valve is the culprit. It seems to be the more likely scenerio. Many thanks.