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Discussion Starter #1
Upgraded to the 2bbl progressive from the original Rochester. So far results have been mixed. When it seems to be functioning properly the motor runs like a dream. But I keep chasing air leaks all around the trans adapt 2025 adapter that allows me to bold on this 2bbl carb to my stock 1 bbl manifold. I have identified the air leaks here by using carb cleaner. I'm running a I6 194 in 63' Nova with other modifications to the engine. I like it simple and clean.

Additional running symptoms are as follows

1) Car shudders under all conditions of acceleration from light to heavy.
2) Bleed screw is out 2.5 to 3 turns and it idles just fine
3) If I punch the peddle the engine bogs
4) At cruising speeds from 35-75 the engine will mis-fire regularly.
5) Very light lean pop on deceleration.
6) Fuel adjustments make little difference.
7) Engine tends to run better while warming. Once it reaches regular operating temps these problem manifest themselves more.

Steps I've taken to solve the problem

1) After installing original gasket, I took it off an applied a silicone gasket dressing. Bare gasket or dressed gasket didn't make a difference.
2) I've tried different levels of tightness on all the appropriate bolts.
3) Howl and curse at the darn thing in the hopes I can intimidate it into working right.

One last consideration. The trans adapt adapter bolt holes did not line up with the bolt holes on the carb. I had to shave away some metal on the adapter to get things to line up close enough to tighten everything down. As far as I can tell this isn't a contributing factor but, eh! I might be wrong?

What do you think the problem could be? What should I do about it?


331 Posts
I put this exact carb on my I6 250.
I did not experience air leaks.
Did you use gasket sealer? This is what I used. Used it on all gaskets, adapter to manifold and carb to adapter.

I spent alot of time cleaning the intake, stuffed a rag in there before starting this task.
I tightened the bolts "quite" tight and also used thread locker on the 6 bolts (2 for adapter to base and 4 for carb to adapter).
After getting the carb on, I checked that all the vacuum hoses were hooked up correctly.
I then reset the timing.
Didn't worry about the kickdown cable until the car was running well.

Tuning instructions here

Picture of my carb installed.

Hard a hard time setting the choke/fast idle, but found a great video explaining it, put it in this thread.

TomFoolry's inspirational post

Snippet from the tuning document...

Idle Mixture Screw and Idle Circuit
The idle mixture screw and idle circuit is CRITICAL to the overall driveability of the car. Not only does it control the idle, it also controls the entire low speed running circuit, as well as part throttle transition. The mixture screw is not just an air screw, as in other carbs,it actually opens a passage and lets in a pre-mixed volume of fuel and air. The more you open it, the more pre-mixed fuel enters the engine. Clockwise is leaner and counter-clockwise is richer.

Assuming you have no vacuum leaks this is a very simple process. However if you cannot get a good adjustment and you have to open the idle speed screw more than 2½ turns to get the engine to idle, then there’s a good chance you have a vacuum leak and you'll need to fix it before going on.

Set the mixture screw by first screwing it in until the screw stops, or bottoms out, then back out the screw 1½ turns. DO NOT FORCE AS THIS WILL DAMAGE THE SCREW AND IT’S SEAT IN THE BODY OF CARBURETOR. Start the engine and let it warm up. Do not worry about the idle speed at this point, just as long as the engine keeps running, as it will be re-adjusted later on. Start by turn the mixture screws in, until the idle starts to stumble and get rough, then slowly turn them back out (turning ¼ to ½ turn at a time) until the best idle quality is achieved. Use your ear, not a scope or gauges, as you want to tune the engine by sound. The car should idle well and small adjustments clockwise (leaner) should make the idle speed drop off. Adjust to the best, fastest, and smoothest running point.
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