Double Barrel intake Question
Thread Starter
8th Gear
Joined: Jun 2012
Posts: 8
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From: Harrisburg PA
Double Barrel intake Question
I'm 14 and just got a 1974 stingray with a stock 350.
i saw a 'vette on TV with a double barrel intake and i really like the look. I was just wandering if there would be any problems with putting it on the 4- barrel Rochester and anything i would need to know like driving with it in the rain. Any help would be appreciated and thanks.
i saw a 'vette on TV with a double barrel intake and i really like the look. I was just wandering if there would be any problems with putting it on the 4- barrel Rochester and anything i would need to know like driving with it in the rain. Any help would be appreciated and thanks.
Team Owner
Joined: Jan 2006
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From: Crossville TN
I think you are describing a twin 4-barrel intake manifold (but I'm not sure). Whether you can use the Rochester carb [assuming you mean a Quadra-Jet, which was the stock carb on that car], you can only install it on intake manifolds with a "spread-bore" pattern.
If you look at the bottom of the carb, it will have openings for the throttle plate 'butterflies'. The size and position of those openings must match those of the intake manifold. The "spread-bore" pattern is when the carb has two small primary openings and two large secondary openings. Other carbs, like most Holley carbs, have a "square-bore" pattern, where all four openings are the same size and equally spaced. Again, to use that type of carb, you would need a "square-bore" intake manifold.
Lastly, I would tell you that putting two 4-barrel carbs on a stock C3 engine [made between 1973-1981] might look nice...but it would be unnecessary, as the engine would need less fuel than one Quadra-Jet could supply. If your intake manifold is made for two spread-bore carbs (quite unusual, if you have one), you could still install it without doing any harm to the engine, as the Q-Jet carbs are self-regulating and will only open the secondary air valve as much as is required for the engine it is (or they are) placed on. Of course, any carb needs to be properly tuned with correct jets, rods, etc. to operate well on whatever engine you have.
Hope that helps with your question. If not, clarify what you have and what you want to do, and we'll try it again.
P.S. If what you have is a 2x4-barrel intake for an earlier version 283 or 327 Corvette engine, it will fit on your engine, but you will need to find two carbs that have the same throttle plate pattern. Early Corvettes used the Carter WCFB carbs; some aftermarket intakes for the small-block Chevy (SBC) engine were made for Carter AFB carbs, which are still widely used.
If you look at the bottom of the carb, it will have openings for the throttle plate 'butterflies'. The size and position of those openings must match those of the intake manifold. The "spread-bore" pattern is when the carb has two small primary openings and two large secondary openings. Other carbs, like most Holley carbs, have a "square-bore" pattern, where all four openings are the same size and equally spaced. Again, to use that type of carb, you would need a "square-bore" intake manifold.
Lastly, I would tell you that putting two 4-barrel carbs on a stock C3 engine [made between 1973-1981] might look nice...but it would be unnecessary, as the engine would need less fuel than one Quadra-Jet could supply. If your intake manifold is made for two spread-bore carbs (quite unusual, if you have one), you could still install it without doing any harm to the engine, as the Q-Jet carbs are self-regulating and will only open the secondary air valve as much as is required for the engine it is (or they are) placed on. Of course, any carb needs to be properly tuned with correct jets, rods, etc. to operate well on whatever engine you have.
Hope that helps with your question. If not, clarify what you have and what you want to do, and we'll try it again.
P.S. If what you have is a 2x4-barrel intake for an earlier version 283 or 327 Corvette engine, it will fit on your engine, but you will need to find two carbs that have the same throttle plate pattern. Early Corvettes used the Carter WCFB carbs; some aftermarket intakes for the small-block Chevy (SBC) engine were made for Carter AFB carbs, which are still widely used.
Last edited by 7T1vette; Jun 27, 2012 at 10:16 AM.
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