Just rebuild the engine in my dad's 69' Fury convertable. He wanted a four barrel carb upgrade. So I got an old Edelbrock performer intake and milled the name off and painted it like stock. Got the engine in car with a Holley 650 vacuum secondary that came with a metering block on the rear for additional tuning. Bought carb off Ebay. Turns out everything had to be moved around to accomodate the Holley. And now the Holley proves to be junk car ran terrible. Put the original 2 barrel back on and every thing runs fine. But, really want to make the switch. Was hearing the Carter Thunder AVS was a great little street carb.

This is a 383 with a cam ground for mileage and a little bowl work behind the valves. Should I rely on the CFM calculator and buy the 500 CFM sense the car is not driven for performance or get the 650 which may give a little more performance on that occassional two lane road sling shot pass?

Leon

650 AVS is the PERFECT carb for that application.

Sheldon

The 650 AVS is a nice carb. I had to jet it up and put bigger accelerator pump nozzles on mine to get it to run right on my stock 340 with heat blocked off of intake. But once it was tuned I loved it.

Did you also go up from .098 secondary jets to say .100? I know I had to go up 8 percent rich on cruise and wide open but I didn't go up on the secondaries. Wondering if I should have! Don't mean to hijack the original post! I just needed to know this! Thanks!

Has anyone tried a 500 CFM Edelbrock Thunder AVS?

Or did everyone just assume they needed the 650. Reason I ask is at 5,000 RPM which is about all this engine will ever turn a 500 CFM should be plenty. Reading the post and seeing that guys are going up on squirters and jets......Well that is a tell tell sign the carburator is too big.

Does anyone know the size of the original 4 barrel for a 383 from the factory?

Leon

I think the 500 is too small because in normal driving the primaries won't feed it enough. So the mileage will get worse because you'll be using the secondaries whereas with a 650 it would be running on the primaries more.

Sheldon

I know guys who have ran a 500 CFM AFB on a 440. Back in the days of decent fuel, he was getting high teens for mileage. You will sacrifice some top end power, but should be stout on the bottom. For a mileage oriented build I would totally go with one.

..i think i read somewhere early 340 was about 485 or 500 cfm and early 440 was 585 cfm.
many different opinions on carb size!

If you are leaning towards the 500, go for it. It will have really sharp throttle response and you'll lose a few hp up top but the carb is good for at least 300 real hp.

R.

max wedge motors had 2- 500cfm AFB's for a race motor.

My '70 Bee had a 335HP 383. The stock Holley on it was less than 500cfm. I have a couple of Carters that came on the single quad 426 wedge motors. Less than 500cfm.

I put a 625 Carter on it and picked up some power and MPG's! Also went with a Street Dominator.

You'll be happy with the 500cfm. Its a great carb.