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Old 06-01-2020, 04:13 PM
topfuel67 topfuel67 is offline
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Default 1966 GTO Tripower Venturi cluster numbers

Does anyone have the correct Venturi cluster numbers for the center and end carbs for a 66 GTO? I tore apart several carbs over the years and didn't label the Venturi.
I have a 38864,2- 16266 that only have 2 tubes and 3- 16266 that have 4 tubes. I have a couple of others, but I'm pretty sure they're for early 60s or late 50's small Rochesters.
Thanks in advance.

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Old 06-01-2020, 04:41 PM
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Dick Boneske Dick Boneske is offline
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The ones with the two tubes are for the end carbs. They have cast numbers 16266 on them
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Old 06-01-2020, 05:12 PM
topfuel67 topfuel67 is offline
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Is the 16266 with 4 tubes for the center?
Thank you

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Old 06-01-2020, 07:52 PM
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Not sure if this helps but about halfway down the float bowl parts list






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Old 06-01-2020, 11:47 PM
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The clusters have casting numbers on them, not the part numbers shown. Thanks for the effort, regardless. I checked and found the following cluster numbers for center carbs. I believe 16266 is a correct number--if it's one with four tubes on it. I also found 31305, 15598, and 26958 on some other large Rochester 2 bbls.

Any of these will work if they have the proper sized idle tubes, idle bypass restrictors, and idle vents. Stock idle tubes for a 389 would be .033", idle bypass .043", and idle vents at about .039". None of these numbers are OK if you're running a lumpy cam.

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Old 06-02-2020, 03:47 AM
topfuel67 topfuel67 is offline
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Thank you all for your replies. I'll measure the tubes to be sure. I'm going with the factory cam and factory specs.

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Old 06-07-2020, 05:22 PM
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Quote:
Originally Posted by topfuel67 View Post
Thank you all for your replies. I'll measure the tubes to be sure. I'm going with the factory cam and factory specs.


The clusters that have the same physical configuration all are the same functionally except for idle tube sizes, idle bypass restrictor sizes, and idle vents.

The later ones--about 1968 and up, have an extra equalizing channel below the cluster, which is not covered with gasket unless you use the proper cluster.

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Old 06-15-2020, 08:52 PM
topfuel67 topfuel67 is offline
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What do the numbers stamped in the corner stand for? Some have a 70, some have 72, some have 68 etc. Is this related to the jet size? Even though it seems most of the factory jets are 55 - 68 range. I haven't really seen too many factory jets 70 and above in the carbs I'm playing with and a lot of these clusters have 70 or 72 stamped. Over the last few years I've acquired about 20 Rochester 2G carbs. Some just plain old 2bbl and some tripowers.
Thanks
Donald

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