Calling any Holley carb experts - the dreaded fuel efficient 1920

[gdizzle]

66 dddddart L6, 225ci, automatic, with single bbl Holley 1920, original. Engine rebuilt 3 months ago.

Ok I am set on figuring my stutter out on this carb.

Everything else checks out, timed, lashed, fuel line mod (Dan). I just rebuilt the carb with the kit from Mikes. I have set the carb per instructions found in both Mikes kit and the Dodge shop manual, and the manual I found online for the Holley 1920. Idle is fine, does not stall and not rough. Starting is fine, hot or cold starts right up even after a few days of non-use.

New gas tank, new filter, lines are clean, no sediment.

I have tried very unscientific trouble shooting:

As I accelerate from a stop, if I push down abruptly (or normally) it will cut out for 1/2 second, then start to accelerate (rough as it accelerates for about 1 second). The only way I can keep it from cutting out is if I slowly (barely push pedal as slow as possible) increase my speed, I mean so slow that people get pissed behind me. Once I reach about 25mph, there is no issue and I can floor it and it will not cut out.

Next test: I am cruising at 45 - 50, I start to coast for a few seconds so it slows down to maybe 30, I then floor it and it will cutout (hesitate) for 1/2 second then move. then I coast for 2 seconds, floor it again and this time cutout is shorter 1/4 second. Then I let it coast and floor it a 3rd time and now no stutter at all. This is all being done at speeds around 30 - 40.

Last test: this only happens under load. If I am in Park and rev engine up, no hesitation or cutout.

When I rebuilt the carb., I did check all settings for float. The float appears very old, orange not black. I weighed it dry at 7.5g. I did not adjust it. Spring is delicate but seems to work. It is missing the baffle.
What I am not understanding, is the cut out due to flood of gas, or too little gas? I tend to think the latter. Is it possible that the float is too light? and is not letting enough gas get in to the metering block? Any and all help would be greatly appreciated.

The only thing I have not done is remove the economizer and check the fuel level while it is at idle.

p.s. if the Float was getting soaked and not rising, wouldn't that get me too much gas?

 

[nm9stheham]

The wet float check is the most accurate for the float setting (removing the economizer). The float being low will typically cause some degree of hesitation and stuttering.

But the symptoms you describe sounds most like the accelerator pump is not filling right OR the check ball in the accelerator pump circuit is not sealing right. This check ball in the pump well has to seat when you push the throttle down so that the accelerator pump squirt goes out into the carb throat; if the check ball does not seat , then the pump squirt just pushes back into the bowl.

If you look at the Mike's Carbs videos on the 1920, he emphasizes this being cleaned out and working properly, and shows how it is done and the ball seat made to work well. I think their kit has a new ball too.

BTW, your float weight is close to the standard 7.3 gram float weight; it is hard to say if your measurement is accurate enough without knowing your scale; I have used a powder reloading scale to get very accurate readings. But if the float is gas-logged heavy, then you would run rich all over. The wet float setting will show that as a high fuel level in the bowl.

 

[gdizzle]

Good info. Here is what is real interesting. I remember looking at the check weight setup, the plug on top of it was all smashed etc...so I did not try to remove it and clean the check weight. The plugs Mike supplies with the kit are too small for the check weight. I looked in the little hole at the bottom where you can see the tip of the check weight and there was a small thin wire, propping the weight up, so it does not go all the way down. I figured that is how it is built, but now I am thinking that is fucked up? If I do reopen the carb and drill out that plug and clean out the check weight, I am not sure how I am going to put in a new plug? where would you even find something like that?

 

[Breadburner]

http://www.carburetor-parts.com/1920_c_131-2.html