69 Vette engine question help needed
Thread Starter
Intermediate
Joined: Apr 2011
Posts: 41
Likes: 2
69 Vette engine question help needed
Just got a 69 Vette
Having body work done on the car/paint
The carb is not working, is there an optimal carb for these engines?
The engine is slightly modified with LT1 aluminum intake, hooker headers, maybe ignition too not sure.
Car has a auto transmission
Can someone point me to someone who knows these engines/car I live in Toronto Canada
Having body work done on the car/paint
The carb is not working, is there an optimal carb for these engines?
The engine is slightly modified with LT1 aluminum intake, hooker headers, maybe ignition too not sure.
Car has a auto transmission
Can someone point me to someone who knows these engines/car I live in Toronto Canada
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
Welcome and congratulations on your new vette. Your on the right forum and its great to see another Canadian C3.
People here like lots of pics. As for your carb I personally would put at least a 700 holley carb on it. There will be others that really like the Q jet, but I personally like the way the holley is modular. As for making more power, that is tuff to do without changes in the motor. Changing the rear gears could make it feel like its making more power. You have to be carefull not to use too much gear or it will rev to high on the highways.
People here like lots of pics. As for your carb I personally would put at least a 700 holley carb on it. There will be others that really like the Q jet, but I personally like the way the holley is modular. As for making more power, that is tuff to do without changes in the motor. Changing the rear gears could make it feel like its making more power. You have to be carefull not to use too much gear or it will rev to high on the highways.
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Welcome to the club! Noticed you mentioned having an "LT1 intake" so I'll make the logical leap that it has a square-bore carburetor flange. With the exception of actual LT1 engines most C3's were originally equipped with Quadrajets which have a 'spreadbore' flange. If you just want a carburetor that will perform well out of the box on what is presumably a mild 350 with a minimum of hassle I would suggest a 670 cfm Holley 'Street Avenger', Summit sells it as a 'HLY-0-81670' or '-80670' depending on whether you want an electric or manual choke. There is one catch, though...unless you've got an LT1 hood or a big-block type hood on your car you can very easily run into hood clearance issues with an aftermarket intake and a Holley carb. This leads to the world of Quadrajets...if you choose to run a low-rise, stock-type intake you can fit a Quadrajet under a small-block-type hood with a stock-type large air cleaner.
As far as the "more HP" issue, that is really more related to camshaft choice (limited without any valvetrain changes) and exhaust- just bolting a big carburetor on top of the motor without allowing the rest of the engine to breathe won't really do anything for increasing horsepower on its own. The nice thing about Quadrajets is that you can bolt one on the car now as it is, and if you go and put together a motor with larger cam or perhaps build a stroker you can still use that carb on the new improved engine...Holleys are more or less 'displacement-specific' in that their idle calibrations are directly related to engine displacement; i.e., you have to use a cfm range that is suited to your combination of cubic displacement and cam size. A Quadrajet is essentially a 'variable-cfm' carb because of its secondary air valve and will work well over a wide range of displacements and cam sizes. IMHO the WORST thing about QJets is that they are not a modular design and are therefore fairly difficult to tune and/or rebuild (especially for the inexperienced)...Holleys are really the best for that.
As far as the "more HP" issue, that is really more related to camshaft choice (limited without any valvetrain changes) and exhaust- just bolting a big carburetor on top of the motor without allowing the rest of the engine to breathe won't really do anything for increasing horsepower on its own. The nice thing about Quadrajets is that you can bolt one on the car now as it is, and if you go and put together a motor with larger cam or perhaps build a stroker you can still use that carb on the new improved engine...Holleys are more or less 'displacement-specific' in that their idle calibrations are directly related to engine displacement; i.e., you have to use a cfm range that is suited to your combination of cubic displacement and cam size. A Quadrajet is essentially a 'variable-cfm' carb because of its secondary air valve and will work well over a wide range of displacements and cam sizes. IMHO the WORST thing about QJets is that they are not a modular design and are therefore fairly difficult to tune and/or rebuild (especially for the inexperienced)...Holleys are really the best for that.
