rochester Quad==396 to small block - Impala Tech
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post #1 of 3 (permalink) Old 10-07-2014, 11:23 AM Thread Starter
Join Date: Nov 2013
Location: rhode island
Posts: 9
rochester Quad==396 to small block

1966 impala rag top with a 283, 60 over (292), cam is one small step up from stock, hyd lifters, HV pump the rest are chevy parts. Running a spread bore 68 manifold with a Roch/Quad off a 1968 396 camaro. The quad is rebuilt and does work however it came off a big block not a small block.
I know these carbs were used on many application by chevy sbc and big block cars and trucks .
Question: is there a way to find the jets, metering rods and ect. sizes for a small block application of the same carb ?, am i wrong to assume big block with size 71 jets ect. would be set up for more cubic inch than s/blocks,
396--283, 327 ?
lien is offline  
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post #2 of 3 (permalink) Old 10-07-2014, 11:40 AM
Join Date: Jan 2006
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There are three different primary venture sizes (two for the Chevy and one for the larger BOP engines). The cfm at wide open throttle are 640, 720 cfm and 850 cfm for the Buick, Olds or Pontiac 455 carb. The good news is that any of these carbs will work just fine on your little 283 because the rear barrels are not only vacuum operated but have a variable venture.

Because of this you can not over carburate the motor. The carb will only supply the cfm that the engine can draw (under load). Other wise you are driving around town with a spiffy looking two barrel.

There are boards that list the metering rods and the jet size. Additionally they list the letter designations of the less commonly encountered stepped metering rods that gave a more uniform fuel/air mix in the mid range where few carbs work well. Problem is knowing the part you want and finding that part are two different things. Chevy no longer sells parts, nor does any one that I know of. Most people who tune these carbs hoard what they have.

Big Dave
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post #3 of 3 (permalink) Old 10-07-2014, 02:10 PM Thread Starter
Join Date: Nov 2013
Location: rhode island
Posts: 9
thank you Big Dave, again you provide great info quickly. The boards that you mention that would have some information, do you know where i could find them ? After that perhaps i would know what to look for at swap meets, ect., all part of the classic car hobby.
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