New 350 Block & Intake with Old Carb Issue

L

LiquidC

Petty Officer 3rd Class
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Apr 6, 2009
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96
Hey guys ... Just got a new 350 from GM with Vortec heads & a Vortec Performer RPM Intake from Edelbrock, and I'm just starting to put it together. I'd like to use my old carb if I could, but the Edelbrock Intake doesn't have the screw hole for the coil-spring enclosure for my carb.

My old carb is a Rochester Quadrajet 4bbl. Take a look at the pic's

The old intake with the carb on it.
IMG00546-20120426-1409.jpg

This is a close up of the screw.
IMG00547-20120426-1410.jpg

My new block, with Vortec heads, & Edelbrock Intake.
IMG00544-20120426-1403.jpg

IMG00545-20120426-1404.jpg


Can I get away with NOT screwing this down (leave it hanging), or is it time to pony up for a Marine Edelbrock carb??
 
Maddoxsdaddy

Maddoxsdaddy

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Re: New 350 Block & Intake with Old Carb Issue

I am going through the EXACT same thing with my motor build. What you have circled is what i call heat activated choke spring. Whan the intake gets warmed up, the spring pulls off the choke on the carb. You dont need a new carb, just a new choke configuration. I had the old style intake and am switching to a performer as well with no accomadations for the choke spring. you can "get away with it". Your carb will simply not have a working choke. Probably a little harder to start???

There are intakes available with accomidations for the choke spring. Just have to do a little searching to find them.
 
L

LiquidC

Petty Officer 3rd Class
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Messages
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Re: New 350 Block & Intake with Old Carb Issue

Thanks Maddoxs ... good info. I wonder if I could "get away" with having my local machine shop make me a small block of aluminum that would allow the heat transfer, and have a hole for a screw & bolt.

Wouldn't be pretty ... but I'd rather not have to ship this intake back for another one.
 
RogersJetboat454

RogersJetboat454

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Re: New 350 Block & Intake with Old Carb Issue

You could also see if you could dig up the parts to convert your old Q-Jet from a heat stove choke to an electric choke. That Q-jet most resembles something used on a early 70's era vehicle. Might be worth checking with a carb rebuilding place to see if they happen to have the parts needed kicking around. While you're there, if you haven't considered it, you may also want to consider getting that carb rebuilt (if it hasn't been done recently). Nothing will ruin your day quicker then bolting an old gummed up carb to a new engine, and have your new engine run lean and burn up pistons.

The other point I will make, your intake manifold is for a square bore style carb. Your Q-jet is spread bore, and the secondaries will most likely interfere with the intake if the carb will even bolt up to that style intake. There are adapters to adapt a spread bore carb to a square bore intake, but they usually add at least an inch of height to the carb mounting which can make this all a no-go in a tight bilge with the tall manifold and a flame arrestor already adding considerable height.

I like the Q-jet but it seems like a Holley or Edelbrock marine carb with an electric choke is looking like a more attractive option for you.
 
J

John_S

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Jun 21, 2004
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4,269
Re: New 350 Block & Intake with Old Carb Issue

RogerJetBoats is correct, that Q-jet will not fit that intake without an adapter plate. Adapter plate in general are a bad idea, but given the rpm intake, carb, and flame arrester, you might be running out of dog house clearance, to add another 1-2".

The Qjet will need to be re-tuned, (jets & rods) coming from a standard head to a vortec head sbc.

Vortec intakes don't have a stove pipe chokes because the heads don't have an exhaust crossover. An elec choke, manual choke, or no choke are the options.
 
J

John_S

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Re: New 350 Block & Intake with Old Carb Issue

Good deal. It still may need some tuning, but is much easier than most other carbs.

You will have to change the fuel line. Some people bend their own. There are CG approved flex lines, or you can get mercruiser lines (around $45), if you are still using the mechanical fuel pump. If it is a newer block, the fuel pump boss has not been machined, in which you need to switch over to elec fuel pump.
 
Bondo

Bondo

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Re: New 350 Block & Intake with Old Carb Issue

John_S said:
Good deal. It still may need some tuning, but is much easier than most other carbs.

You will have to change the fuel line. Some people bend their own. There are CG approved flex lines, or you can get mercruiser lines (around $45), if you are still using the mechanical fuel pump. If it is a newer block, the fuel pump boss has not been machined, in which you need to switch over to elec fuel pump.
Click to expand...

Ayuh,.... The Manual at the Eldebrock website, 'n a Street/ Strip tuning Kit is Invaluable....

The Best $30.bucks I ever spent, is that Kit.....
 
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