General Category > Quadrajet Carb Talk and Tips
LOW budget engine not working well....HELP!
jberenyi:
The newly rebuilt engine is a matching number 350 bone stock except for .030 over on bores. Clifford built this carb from scratch because I did not have a carb for him to build. This Vette uses 7044206. When I got it back it ran just fine with the tired engine but now its a completely different animal. I also had Cliff rebuild the original distributor and he re-curved it to be in at 36 deg at 2800 rpm which I have confirmed it is. Initial timing is set to about 12 deg at 700 rpm. Vacuum is about 15Hg at 1000 rpm and it will get better as she breaks in. I confirmed there are zero vacuum leaks. When I last spoke to you all I noticed that with 5 turns out on the mixture screws and cupping the airhorn with my hand the rpm would rise signifying a lean condition. I turned the idle screws out to about 8 turns and and it got rid of the lean condition about 90%. If she idles at 750 rpm and then cup with the hand it will go up to 800 rpm but that's it. The carb was provided with 75 jets and a 44 primary which is concerning because the specs say it should a 46. But me being at 4500 ft. above sea level maybe its okay. Anyhow, at 8 turns out she's running better but not perfect with respect to idle only in drive or park. All other things like cruising, acceleration, etc. she's perfect. I really think we have an IFR that needs attention on sizing. Thought's anyone?
Kenth:
In 1974 Corvette uses a std performance Qjet or a high performance Qjet.
The std 7044206/7 units uses 46B pri rods #75 jets .034" idle tubes .100" idle bypass air and CH secondary rods.
The HP 7044210/1units uses 43B pri rods .037" idle tubes .120" idle bypass air and DA secondary rods.
In any case i would open the idle needle holes to .095" and idle tubes .002" to start with.
jberenyi:
--- Quote from: Kenth on August 01, 2021, 12:59:43 PM ---In 1974 Corvette uses a std performance Qjet or a high performance Qjet.
The std 7044206/7 units uses 46B pri rods #75 jets .034" idle tubes .100" idle bypass air and CH secondary rods.
The HP 7044210/1units uses 43B pri rods .037" idle tubes .120" idle bypass air and DA secondary rods.
In any case i would open the idle needle holes to .095" and idle tubes .002" to start with.
--- End quote ---
Good info. One thing to note, I know this carb's casting number is not the one I listed above. Also, my baseplate is missing a port for the vent hose on my charcoal cannister! After paying about $800 for this carb I'm disappointed its not working 100% on a spec build bone stock 1974 350.
Cliff Ruggles:
What are the engine specs?
You've mentioned "bone stock build", but no details.
What cam was used in the engine (specs).
Overbore, dished pistons, flat tops, and what head gaskets?.....
Mudsport96:
Sorry to the original poster/thread starter. I know you pm'd me, but i dont call numbers off of the internet man. Post up your build info here and we can help. I know you said bone stock rebuild, but many parts are not to factory spec
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