Q jet EFI
Race Director
Joined: Jan 2000
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From: San Jose CA
If it's like a regular square bore carb, the bolts won't line up and you'll get significant interference on the primary throttle blades.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Just contact the EFI manufacturer to see if they make one to replace the Q-jet. Since almost ALL GM cars made between 1965 and 1980 had Q-jets on them, I would be amazed if they didn't have the unit you need.
Race Director
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From: San Jose CA
Racer
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I thought it was approved while mounted to the stock intake?
Race Director
Joined: Jan 2000
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From: San Jose CA
It'd need an adapter to fit the stock intake.
There're probably at least a few cars in the "all GM cars with a QuadraJet" group that could fit that throttle body and adapter, but Corvettes certainly aren't one of them.
There're probably at least a few cars in the "all GM cars with a QuadraJet" group that could fit that throttle body and adapter, but Corvettes certainly aren't one of them.
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Race Director
Joined: Jan 2000
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From: San Jose CA
Team Owner
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Sucks to live in Kalifornia.
Drifting
Joined: Aug 2015
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From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
"Note that the Fitech throttle body will bolt directly to a spread bore 4-BBL manifold but may leak without the adapter plate."
You can sort of see the mounting holes here:
No idea about the throttle blades though. They may well be the reason for suggesting an adapter plate is needed.
Drifting
Joined: Aug 2015
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From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
Maybe the throttle blades are higher in the throttle body, allowing them to clear? Or maybe not, and it actually does need the adapter (the wording in the instructions makes me wonder if it's actually needed or if they're just covering themselves). If I have it off the engine again then I'll have a look to satisfy my curiosity.
Edit: Looking at the 1st manifold you pictured, the gasket provided wouldn't seal between the holes (it's an open square gasket) and so wouldn't seal that manifold around the front of the carb/throttle body. It possibly might seal to the 2nd manifold, hard to know without comparing in person.
Edit: Looking at the 1st manifold you pictured, the gasket provided wouldn't seal between the holes (it's an open square gasket) and so wouldn't seal that manifold around the front of the carb/throttle body. It possibly might seal to the 2nd manifold, hard to know without comparing in person.
Last edited by Metalhead140; Oct 11, 2016 at 08:37 PM.
Race Director
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From: San Jose CA
One thing is for sure - without a dual pattern manifold, there will be problems with the throttle blades. Either they design them to fit both styles and the primaries are spread-bore sized and recessed, or they are square-bore sized, recessed, and you get fairly significant turbulence as the inbound air charge slams into the smaller opening at the intake manifold.
Drifting
Joined: Aug 2015
Posts: 1,939
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From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
One thing is for sure - without a dual pattern manifold, there will be problems with the throttle blades. Either they design them to fit both styles and the primaries are spread-bore sized and recessed, or they are square-bore sized, recessed, and you get fairly significant turbulence as the inbound air charge slams into the smaller opening at the intake manifold.