1967 427 Holley 2300C Carburetor issue?

[Ken A.]

Re: 1967 427 Holley 2300C Carburetor issue?

I thought these were NEW carbs. BTW, Holley does not recommend drilling the squirter.

[Timothy B.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

FWIW, these end carburetors have a idle circuit and a metering plate inside which contains the idle feed restriction and main jet, there should be two air bleeds on each side. The transfer slot is fueled by the same port as the dribble hole. The dribble hole is below the blade so it sees manifold vacuum and keeps the transfer slot wet so when the blade moves up there is fuel flow without hesitation. The dribble hole also keeps the fuel fresh because the car can be driven like a two barrel. If this hole gets larger than .022 the idle can get rich.

The PCV valve can also contribute to idle air as a calibrated vacuum leak, I don't think you will ever get these blades to fit even, they are not supposed to be tight because they will stick closed and vacuum will not pull them open. I can't help but wonder if the air bleeds are drilled the same. If the mixture screws are approx 3/4 to 1 turn out for best vacuum and idle quality I think it's fine. If you are still experiencing hesitation you may want to try a larger pump squirter.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

I thought these were NEW carbs. BTW, Holley does not recommend drilling the squirter.

They ARE new, and by the way, I've had several people with new 2300's describe the same problems I've been having. The NEW squirter was marked "21". It wasn't 0.021". It was 0.018"+. I made it 0.025" as recommended. If I wasn't supposed to drill it, my error, but it worked substantially better/ Off idle stumble is nearly gone, but still have issues getting a good idle mixture. Also still getting venturis dripping at higher RPMs.

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I reran today after reworking the Rear carb throttle plates. I could not improve the plate to bore seals. I reran and have the same problems as before, however, the stumble off idle is nearly gone, which I attribute to the enlarged squirter diameter.

I removed all three again and installed the ones that were on the engine originally, old service replacements from year "4"..... 74, 84, or 94....not sure. These were running fine on the engine before I took the car apart and decided to get correctly dated NEW 2300's. I have a few leaks and stuck floats on both F & R secondary 2300's so I have to open them up to clean them out. The center 2300C was fine but had to shut down right away. I'm doing this to get a baseline.

My patience is thinning. I may convert this engine to Rochester fuel injection to get it to disperse the fuel properly.

===

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

FWIW, these end carburetors have a idle circuit and a metering plate inside which contains the idle feed restriction and main jet, there should be two air bleeds on each side. The transfer slot is fueled by the same port as the dribble hole. The dribble hole is below the blade so it sees manifold vacuum and keeps the transfer slot wet so when the blade moves up there is fuel flow without hesitation. The dribble hole also keeps the fuel fresh because the car can be driven like a two barrel. If this hole gets larger than .022 the idle can get rich.

The PCV valve can also contribute to idle air as a calibrated vacuum leak, I don't think you will ever get these blades to fit even, they are not supposed to be tight because they will stick closed and vacuum will not pull them open. I can't help but wonder if the air bleeds are drilled the same. If the mixture screws are approx 3/4 to 1 turn out for best vacuum and idle quality I think it's fine. If you are still experiencing hesitation you may want to try a larger pump squirter.

Just noticed your post Timothy.....

Yes, today when I had the rear apart today I did in fact check that dribble hole and how it's also in the same cavity as the slot. I took some photos of that area. The hole is around 0.018" IIRC.
PA190015.jpgPA190016.jpgPA190017.jpgPA190018.jpg

I've been wondering about the throttle plates also since I looked more closely at the old 2300's I have from the engine. I see similar gaps in those throttles. Maybe I'm chasing a ghost, I'm unsure.

I have to break away from this tomorrow but will be back on it Wednesday.

Thanks
Rich


A few more photos for reference.
PA190020.jpgPA190021.jpgPA190022.jpgPA190023.jpg

PA190024.jpgPA190025.jpgPA190026.jpg

[Timothy B.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

Can you describe to me your concerns about the idle mixture, also, what rpm is the main circuit dripping. If you lower the float in the primary three or four flats the main circuit will start later and vice versa.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

Can you describe to me your concerns about the idle mixture, also, what rpm is the main circuit dripping. If you lower the float in the primary three or four flats the main circuit will start later and vice versa.

Timothy, I'm heading out for the day to the FL West Coast right now and won't be back until late so I won't be able to further respond until then....

The idle mixture appears reasonable as I', getting a good variation with the idle mixture screws now. The main problem was that debris and now that's much better.

The problem now is I'm getting sputtering fuel in the venturis at 1500-2000 rpm and more. In post#19 my latest video clip shows the condition. It's causing popping and sputtering in the exhaust too. Just not crisp yet. I checked the float levels of all 3 carbs and appeared correct.

When I get back on it tomorrow I'm thinking I'll re-install the new F & R 2300's and leave the original 2300C primary there for my baseline tests. Maybe I just need to fine tune the new 2300C better. Maybe as you suggested to adjust the float level lower will help. it may be just that simple. I hope.

Thanks for your persistence and patience to help me resolve this.

Rich

[Timothy B.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

At main circuit start up when the air flow through the booster venturi creates a low pressure signal, air is pulled in through the main air bleed and then through the emulsion bleeds and it blows the fuel up into the nozzle like spray off the ocean. At main circuit start up the fuel level in the main well is the same level as the fuel in the float bowl so if the level is lower it will take a stronger signal to lift the fuel and start the main circuit.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

............... If you lower the float in the primary three or four flats the main circuit will start later and vice versa.

Okay. The stock float setting is observed by seeing fuel at the bottom edge of the bowl inspection screw hole, correct? So I should expect the fuel level to drop below that somewhat. I'll try that after I re-install the new 2300's. I will test it to see if it reduces the venturis dripping versus atomizing.

Rich,

At main circuit start up when the air flow through the booster venturi creates a low pressure signal, air is pulled in through the main air bleed and then through the emulsion bleeds and it blows the fuel up into the nozzle like spray off the ocean. At main circuit start up the fuel level in the main well is the same level as the fuel in the float bowl so if the level is lower it will take a stronger signal to lift the fuel and start the main circuit.

Thanks for the explanation. I was reading up on my Holley theory of operation today on my seven hour round trip ride in the back seat of a SUV and I am beginning to understand these systems. I just need to put theory into practice now and get these running properly.

Thanks,
Rich

[Timothy B.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

If you lower the float in the bowl it will lower the fuel level in the main well and should delay the main circuit start up until a higher rpm/signal.

Some metering blocks have what's called a kill bleed in the main well, it's a small hole to bleed off the signal until overcome by a stronger signal and it delays main circuit start up. I wonder if the original metering blocks had this and the new Holley blocks don't.

It's a area I can't speak from experience in but there are carburetor tuners that can. This tuning can be like a disease because you want to keep changing things trying to improve the engine. That's why it's important to only change one thing at a time to see what works and if not you go back and try something else.

It's OK to lower the float below the sight plug, this is just a general guide.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

If you lower the float in the bowl it will lower the fuel level in the main well and should delay the main circuit start up until a higher rpm/signal.

Some metering blocks have what's called a kill bleed in the main well, it's a small hole to bleed off the signal until overcome by a stronger signal and it delays main circuit start up. I wonder if the original metering blocks had this and the new Holley blocks don't.

It's a area I can't speak from experience in but there are carburetor tuners that can. This tuning can be like a disease because you want to keep changing things trying to improve the engine. That's why it's important to only change one thing at a time to see what works and if not you go back and try something else.

It's OK to lower the float below the sight plug, this is just a general guide.

Timothy, Interesting info regarding the metering block. I have many photos of it on the PB page, not sure if it'll be a clue. Page 6 is where I tore into the 2300C to clean the packing debris and took many photos for reference.

http://s684.photobucket.com/user/richmz/library/Holley%20List%203660%20pics/Repair%20All%20Three?sort=2&page=6

I can also take apart the early 2300C and compare later. I think it's 1974 vintage as a black ink stamp is on top of the bowl "2974". List date stamp on front of air horn is 2924.

I decided to put all 3 new 2300's back on this morning and do as you suggest regarding the float adjustment. I'll report back with results.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

Can you describe to me your concerns about the idle mixture, also, what rpm is the main circuit dripping. If you lower the float in the primary three or four flats the main circuit will start later and vice versa.

Rich,

At main circuit start up when the air flow through the booster venturi creates a low pressure signal, air is pulled in through the main air bleed and then through the emulsion bleeds and it blows the fuel up into the nozzle like spray off the ocean. At main circuit start up the fuel level in the main well is the same level as the fuel in the float bowl so if the level is lower it will take a stronger signal to lift the fuel and start the main circuit.

Timothy, Thank You. I think I got it.

This afternoon I lowered the float level. I took it down 3 flats, tried it and was a bit better, less dripping in the venturis. I have a old Holley Guide that states each 1/6 turn(CW) it drops the level 1/16". So I went a few more, and the level is now down about 1/4" from the bottom edge of the site hole. BTW, before was actually above the bottom edge of the site hole. When I unscrewed it originally, fuel came out so I thought I was alright, then I removed the screw and a lot came out. It was much too high from the beginning. I believe this simple error on my part had much to do with the problem. I think I was chasing a ghost.

I also found a problem with the right side emulsion screw seal. It was dislodged a bit, probably sucking air, so I reinstalled it with a tighter fit and I believe that helped also.

I ran it up, re-adjusted the emulsions for best vacuum and idle, about 1 1/4 turns out on each side, and it's much better. Minimal venturi dripping at raised RPM.

https://youtu.be/38L-OpWeey0

Also, I controlled the temperature for a higher overall run to about 180 earlier and reacted much better too. I think I have it solved. When the engine is run under normalized temperature in the engine bay with air cleaner and normal configuration, after a few final t w e a k s I think it'll be fine.

Thanks for your help, and for everyone's help with this oddity that I had. I certainly learned more about Holley's with this adventure.

Rich

[Timothy B.]

Re: 1967 427 Holley 2300C Carburetor issue?

Rich,

Glad it helped out, FWIW here is a picture showing the Holley metering block. The middle picture shows holes #22, they are air bleed holes into the main well. The center hole is approx at float level and that is the hole that allows air to start the fuel flow and blows it up to the nozzle.

The top hole is above the fuel level and is a kill bleed, it's not on all Holley metering blocks and it's purpose is to bleed off some signal and delay main circuit start up until it is overcome by a stronger signal, some blocks have it and some don't. I am not saying you need to drill a kill bleed, just showing how the main circuit start up is changed using this bleed.

[Richard M.]

Re: 1967 427 Holley 2300C Carburetor issue?

Thanks Timothy. I printed that out and going to compare to my photos of the actual block here. I also took the old 2300C apart this morning to check jet sizes. Those are # 64's. I compared to the new 2300C jets(in pictures) and they're the same.

For a while I wondered if the new jets were wrong, but appear the same as what was on the car before, which ran very good.

RIch