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Hi I have a 68 fastback 289 that is stock internals maybe a small cam. I am getting around 8mpg around town and it has a flat spot in the throttle around 15-1700 rpm. It also doesn’t pull very hard and sounds like it’s not running smooth. The timing is dead on and everything else is great. I was wondering what metering rods and springs everyone’s running. I know the 600 is a little big but I got it for 40% off so I couldn’t pass. Also any tips on what size jets to put in would be great.
 

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I might would buy another 600 if I saw it for 40% off. Good score!
Many people say that the 600 is too much carb for a 289. Personally, I don't know. What I do know is that the tuning kit for that carb is very handy and will help you dial in you new carb to get the most out of it. They cost about $50.
 

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I put two manual choke avs2 500s on my 289 works great haven't touched them.
Remember the manual choke version is calibrated different than the auto choke.
you said timing is perfect. If you changed the cam you can only use the book as a guide.
Did you check your mechanical advance every 500 rpm to see if it is at least doing what the manual says?
is the vacuum advance working ?
what carb did you buy?
I would call edlebrock tech

Ken
 

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At one point, I ran a 1405 Eddy. The Edelbrock Tech site has a chart of their metering rods, springs, jets etc. and their affect (lean/Fat) on a their carb. I referred to it numerous times. Every engine is different, so, it's best to wing this on your own.. IMHO.
 

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My experience with edelbrock carb tuning was always a struggle to get around the flat spot. Did lots of reading on it but never really was satisfied. Try a bit more timing and adjust the lever for the squirter, I believe there are three holes. You may find you need the full tuning kit to change needles and jets to reduce the air fuel ratio for a 289.
 
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