Replacement carb?

A

atomicmonkey

New member
I have a 1972 Scout II with a 345 auto (I think 727, as the bell housing is not magnetic). This week I am going to order from IHPA a pertronixs, new spark plugs and wires and a shop manual. Ignition first! Next payday will be a big job for my new truck, I want to pull the intake manifold and replace the welch plugs as I have a small coolant leak collecting on the valley pan. At the same time I would like to put on a rebuilt carb. I doubt this carb has had any real tlc and I use this as a daily driver. I will also address a very poor vacuum system. My big question is: is there a drop in rebuilt holly carb that is fairly straight forward that I can get through IHPA? I can rebuild my 20hp honda outboard carb in my sleep, upside down...but this carb makes me feel a bit of a ninny and I need it to work so I can go to work! Thanks!!


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That 2300 series carb is really pretty easy to rebuild. As long as the idle fuel passages are not blocked, I'd get a kit and rebuild it.
 
Thanks for the vote of confidence!! What I thought about was getting a good rebuilt one from IHPA to put on, then rebuilding the one that is on there now. I think having some time to try and learn it without being under the gun would be a good thing for me :)
 
IHPA no longer offers rebuilt carbs or a carb rebuilding service. They do have brand new, aftermarket versions of the Holley 2300 (list 0-7448) available for purchase. Like chappie said, that carb you have should be a pretty good one once it has been gone through, sterilized and kitted with a Holley brand kit.
 
If it runs reasonably well now rebuild it. Those 2300's are smooth as silk when right.
When you do rebuild it, pay very close attention to the gaskets you install. Make sure they match 100% where there are passages. This is a very common mistake.

Make sire to blast all passages and that the fluid leaves through the connecting hole. The major air horn casting has 4 air bleed jets/passages in them visible under the choke plate. Make sure they are clean and clear. I like to use a brass wire off of a brush to clean them. Blast them with cc as they exit where the main metering plate seats..
Install a new base gasket/insulator too. IHPA should have them along with or in the carb kit.
http://www.IHPartsAmerica.com/store...e=ion&product_code=dpc-carbkit&category_code=

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Thanks Robert. It seems to run good right now, a bit Rich. I will know more after I replace the ignition set up this week. Right now it is terrible at cold starting. I am sure most of it is vacuum related but was wondering your thoughts on putting in that electric choke? Thanks again!
 
Ok...I installed a pertronics, new plugs and wires and cleaned up the vacuum system as good as I can for the moment. I rebuilt the carb and installed an electric choke. It all went fairly straight forward except for a few small things: when I put on the carb for the first time after the rebuild, the engine started right up and the idle went really high. I shut it off and thought it might be the power valve (I have no idea why I thought that!). I popped off the carb and pulled off the power valve and realized that I had mistakenly put two gaskets on it. I swapped it out with the old one and re installed the carb. It runs great now, but maybe a bit Rich. A neighbor said that I should put on a 5.5 power valve instead of the 6.5 that came with the rebuild kit. Any thoughts? I usually discount much of his advice as he is a top fuel dragster mechanic and really want me to get rid of my motor for a more performance one (never). The other thing is the fuel valve seat that came with the kit needs an adjuster nut and bolt. The one on my carb has a solid top with a straight screw driver slot built in. I could not put the new one in. Any thoughts on that?
The engine (304) is running super smooth with good pick up. The vacuum is a bit low to me, around 15" at sea level, maybe a vacuum leak somewhere, I will keep looking. It still runs a bit Rich, the mixture screws are darn near all the way out, but that is where the gauge likes them to be.
Super thanks for taking the time to read this!!
 
atomicmonkey said:
ok...I installed a pertronics, new plugs and wires and cleaned up the vacuum system as good as I can for the moment. I rebuilt the carb and installed an electric choke. It all went fairly straight forward except for a few small things: when I put on the carb for the first time after the rebuild, the engine started right up and the idle went really high. I shut it off and thought it might be the power valve (I have no idea why I thought that!). I popped off the carb and pulled off the power valve and realized that I had mistakenly put two gaskets on it. I swapped it out with the old one and re installed the carb. It runs great now, but maybe a bit Rich. A neighbor said that I should put on a 5.5 power valve instead of the 6.5 that came with the rebuild kit. Any thoughts? I usually discount much of his advice as he is a top fuel dragster mechanic and really want me to get rid of my motor for a more performance one (never). The other thing is the fuel valve seat that came with the kit needs an adjuster nut and bolt. The one on my carb has a solid top with a straight screw driver slot built in. I could not put the new one in. Any thoughts on that?
The engine (304) is running super smooth with good pick up. The vacuum is a bit low to me, around 15" at sea level, maybe a vacuum leak somewhere, I will keep looking. It still runs a bit Rich, the mixture screws are darn near all the way out, but that is where the gauge likes them to be.
Super thanks for taking the time to read this!!
Click to expand...

That vacuum is low. Do you have a tach connected? What is your hot idle speed? At sea level, you should be seeing steady high teens hg or better. Needing to have the mix screws all the way out to keep it running when they should be most of the way in (minus 1.5 - 2 turns) for lean best idle and max steady vacuum tells me something ain't right with your carb innards. Possible gasket mismatch. This isn't a pv issue. Dragster boy needs a ritilin. We're dealin' with farm implements here. The kit pv should be fine for all around driveability. As for the needle adjusted issue, I need to see some pics for comparison sake.
 
Couple more things for you to weigh in on. Where are you sourcing power for the lektrik choke? Have you witnessed choke/butterfly action and motion from cold start through warm-up? At cold start you should see the plate snap closed with a stab of the throttle. This should also engage a fast idle speed of @ 1600 revs. As the engine warms, you should be able to watch the plate slowly but gradually open to a full vertical position. The idle speed should also step down in @ 200 rpm increments until curb idle is reached.
 
I will get a tach on the way to work on Wednesday, I have a feeling I will be using it a lot! The hot idle is roughly 600rpm (I am guessing at this point, it is very slow but smooth). I pulled the eclectic choke power from the windshield wiper motor as suggested. When the engine was cold, I did one pump of the pedal and the choke plate closed with about 1/4" open. For the first time since I have had the truck, the engine started on the first try with no help from the pedal. The rpm's went to what I think is 1600rpm. As the engine started to warm up the choke plate slowly started to open. It took 7 minutes to full open. The rpm's stayed at 1600 the entire time until I pumped the pedal one more time where it slowly (4 seconds) dropped to the hot idle speed.
I will recheck the vacuum in the morning also (hot, using the line from the carb to the dist)
I would love to know what to do about the fuel valve seat also.
Thanks for your help!!!

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Ok...just fiddled around with the mixture screws, idle and vacuum. Again, until I get a tach in the morning, these are just guesses. At approx 650rpm, I have 16" (very steady) and the mixture screws are out 4 turns.
 
Your description of your choke function is overall pretty good. The closed plate gap could be tighter, but you might get by leaving that alone until the colder months return, especially in kowlifornikate. Sometimes the fast idle step down function is tough to get working right. Kind of a clunky design by Holley in my opinion. Using the line from the carb to the dizz to take your vac reading probably won't work as that is likely to be a ported source. A ported source is above the manifold rather than directly from the manifold. There is little to no vacuum signal present at curb idle from a ported source.
The replacement needle adjuster requires a special lock nut and flat screw. It won't work with that monstrosity of a nut that you have on there now, but I think you already knew that. Did the kit not come with the matching adjustment fasteners? I guess I'm failing to understand why you're not able to just switch things over as a unit. I'm sorry, but you need to make the issue more obvious to me, cuz I'm not connecting your dot. Again, 4 turns out is generally about twice as many turns out as we typically shoot for.
 
The new needle adjuster did not come with a nut or flat screw. The old one that is installed right now has a large nut but the flat screw is built into the needle adjuster. It looks like I need to find a Holley store and get those two parts so that I can make the new needle adjuster work with my carb.

What types of things would cause the mixture screws to be so far out?

At this point the truck is running better than it has since I have had it. I am just perplexed about the mixture screws and the strange needle adjuster that I have now.

Thanks!!
 
As mentioned before, an internal leak or blockage, either of fuel or vacuum. I believe it is closely related to your below normal vacuum reading. The good news is you've gained some ground. The bad news is I think you May need to go back inside the carb for a second, extra careful look at the gaskets and the gasket mating surfaces for any hole mismatches. Very few folks will hit the ball out of the park on the first at bat, so don't feel bad.
Now I have to ask, did you actually soak the carb parts overnight in some kind of carb dip such as thyme cold parts soak or berrymans carb dip? Or did you just spritz some carb cleaner spray here and there and chase it with a few blasts of compressed air? I'm just trying to get a sense of how thorough your break down and cleaning process was. The point here is that the cleaning process needs to be fairly extensive. What happens to your idle quality if you turn the mix screws in say two turns each? Does it just completely go to shit or what?
 
The good news is that I feel much more confident in opening the carb up. I soaked the broken down pieces in carb cleaner for a few hours then spent some time blowing out all the passage ways. I think next week, I will pull it off and do a full overnighter at the carb spa. I can then spend some quality time assuring myself that the gaskets are correct and I can put back in the new power valve that came with the kit.

When I screw the idle mixture screws in one full turn, it turns to crap, 1 1/2 turns will kill the engine.

Should I keep the old needle adjuster or should I track down the parts to make the new one that came in the kit work?

Thank you!!
 
Get the new seat adjuster parts if you can. Make sure you have the associated gaskets for those parts too, otherwise you'll have a major fuel leak there.
 
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