2300C woes

M

My73WM

New member
Hey fellow enthusiasts,
I have a 2300c aftermarket carb on my 345. It has an electric choke, but I do not know what the distributor is because it is caked in oil. The carb has size 55 jets, which I m not sure if they are the correct ones for my area, I live in md, which is about 100 feet above. I had to rebuild it, with a little help from my friends. Once we put it back on it ran pretty good. I drove it 30 minutes home with no problems, but now that I have it home it doesnt seem to want to idle. It will start but wont idle, just wants to die. I didnt not have the positive side of the electric choke hooked up when I drove it home, but now that I have hooked it up, it just doesnt want to run without me holding the pedal down.
Any ideas would be appreciated,
Brian
 
Hi Brian. Welcome to the forum. The one thing that jumps right out at me which could be causing your issue is with your power source to the electric choke. The choke circuit must be energized whenever the engine is running. That means it should be sourced from a key switched "on" source. For it to receive energy the way you have it wired, the key would have to be switched to "acc", and obviously the engine wouldn't be running at that point. Do not source this power from the coil + terminal as that will not provide full b+ voltage.
 
Scoutboy,
good info. Could I use the selector switch for my gas tank then? That should work, right?

Thanks again for the help
 
Any source that will provide full voltage only when the key is on and engine running would be acceptable. I'm starting to second-guess myself about my earlier comment regarding the acc position. After I posted that, I started thinking about accessories like radios which receive their power from an acc circuit, but also work when the key is on. My statement about your circuit not being energized when the key is on May be incorrect. That said, it would still be better to source from a key on postion rather than acc. Lets just say you were listening to the radio with the engine off for x amount of time. The choke would be energized that whole time the engine was off, which is not what you want. The bi-metal spring inside thermo housing needs to be able to cool off while the engine is shut off, even for a 15 minutes, so that the choke can operate properly. Hope that makes sense.
 
my73wm said:
...I have a 2300c aftermarket carb on my 345... ...the carb has size 55 jets...
Click to expand...

Posting the carb's Holley list number would be helpful. The number is usually stamped on the forward vertical aspect of the air horn/choke plate housing. To me, when someone says *aftermarket Holley 2300*, I think of either the 350 cfm #7448, or the 500 cfm #4412 carburetor.
 
Getting back to this Brian, when you were driving with no power supplied to the choke, were you forcing the choke plate open manually? The way this style of choke is supposed to work when properly adjusted is as follows:

on cold start, one pump of the gas pedal sets the spring loaded choke plate almost fully closed. Once the engine starts, it should quickly rev up to and hold at a fast idle speed of @ 1600 rpms. As the spring inside the choke housing warms from the power being supplied to via the wire, it will very slowly, but gradually pull the choke plate open. As this is happening, the fast idle cam with graduated notches is also moving, allowing engine speed to gradually step down to @ 1400, then @ 1200 and finally @ 1000 before falling all the way to curb idle once the choke has opened fully. This is all a timed event that you can watch happen over the course of several minutes with the filter canister removed. The choke plate must be able to open and close fully and easily without sticking or binding up.
 
This 2300 is the 350 7448 carb, sorry for not mentioning that.

When I ran this down the road, I didnt have the choke open with anything, it just ran without the positive hooked up, now that I think about it, the truck seemed to have a little hesitation, like when I would give it a little gas, it would want to "hicc-up" sort of. Now I just cant even get to stay diling to watch it do anything.
Thats great info scoutboy74. If this electric choke is not hooked up properly, what would the truck want to start at all? Because it is not able to idle at all, not even long enough for me to look under the hood. I am going to try and see what happens if I hook the positive side of the electric choke to a on/off swiych and see if that makes any difference. I wont be able to work on it until this weekend, but I will keep you posted with what happens.

I appreciate the help with this
 
Those are excellent carbs for these engines. No need to hook the choke + to an on/off switch. When an engine only wants to run with partial or full choke applied at all times, that indicates a significant vacuum leak which can be either internal, external or even both. Vacuum leaks inside the carb (internal) are most often due to a gasket issue. For example, the wrong one was used which is either blocking off a passage that shouldn't be blocked, or not blocking off a passage that should be blocked. An external vacuum leak is usually found within the hoses and fittings that run between manifold vacuum ports and vacuum operated accessories such as power brake boosters etc. And/or a ruptured diaphragm inside an accessory.

What is often a helpful aid to others offering diagnostic help is well focused pictures of your engine bay including wide angle from either side and closer shots of individual components. If you have access to a digital camera, I encourage you to do some well lit snapping and post them up here for us to look at.
Also include any background information on this vehicle that you know of, like how it was running if at all before the carb work, or if you were using a different carb before. Details like that can help paint a better picture for us. Cyber-repair is a difficult process, but there are a number of participants on this forum who've gotten fairly proficient at it. Success involves a lot of input from the man on the scene.
 
Ok, I was able to dodge the rain drops and take some snap shots of my carb. I noticed that the choke plate was all the way open and I could not move it. I thought that it should be closed, am I right?

Hope these pics help.

Thanks,
Brian
 

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Thanks for the pics. Pushing the throttle to the floor once the thermal spring has cooled sufficiently will reset this style of choke to the closed position if all adjustments are within spec.

Tell me more about your rebuild. Did you use a Holley branded kit? What procedure did you follow for setting the idle mixture screws? Have you made any attempt to adjust the idle speed set screw?

Not that this is related to your issue, but I'm going to mention a couple house keeping items that should be attended to. First, your throttle return spring setup looks kinda dicey to me. Second, the slotted bar that connects the throttle linkage to the transmission kickdown pivot bracket is on backwards. I've attached a picture to illustrate the correct setup.
 

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Well, a little history of this truck. I bought it from out west and there was no history given to me about it, but from what I can tell this thing was beat up and rigged together in a lot of ways. It was just mistreated something fierce, so it doesnt suprise me that this carb was in such bad shape.
As for the re-build, I read up on this carb on this forum with michael mayben and yourself, which lead me to buying the correct re-build kit through advance auto. I had some help with the re-build, another ihc friend who has quite a bit of experience with these, so I am sure it was put together right. I did not touch the needles or the idle screws yet because I wanted to make sure I knoew what I was doing first. I am just not that familiar with these carbs that much.

Hope this helps.

Thanks for your input and the pic was great...I will switch that over right away
 
Alright. Well let's start with the idle mixture screws first. They are the small needle screws, with one on either side of the carb protruding from the metering block. Take a small screwdriver and turn both of these screws clockwise, but do so gently. When you begin to feel some resistance, stop. At that point, back each screw out an identical two full turns and stop. Does your choke plate close up at all when the throttle is cycled either with your foot on the pedal or by hand? If not, we'll need to address that as your engine will most likely want some choke to keep it running on a cold start.
 
Might consider getting the 1/4" thick Holley gasket with the 'heat shield' for under the 350 cfm carb. Someone will post the part#. If you open the carb fuel bowl, change the main jets to #63 if you have the 87 octane e-10 gas in the area. Those #50 series jets are for the smaller 275cfm 2300carb. Way too 'lean' for sea level operation. Check the accelerator pump diaphram for the 'yello/green' material, which works longer with the ethanol added in the fuel much better than the 'black' rubber pump.
 
Yes, the #55 main jets are too small for your application. The standard main jet size for the #7448 carb is a #61. This usually works quite well for an average IH 304/345 from sea level up to around 2500 ft elevation. The standard size power valve is an 85. You can usually get away with going down one size in the main jets if you use a two-stage power valve.

The felpro part number for the insulating/heat shield base gasket is 60677.
 
Ok, I will look into the jest and the heat shield. By not having the right jets and the het shield, will that make my truck not want to idle? I have not had anytime to work on it. I wont be able until tomorrow or the weekend, it is supposed to be nothing but rainy here all day tomorrow and weekend, but I will let you guys know what I have found.
I saw what you were saying about the pivot bracket being on backwards and I want fix that first. I am going to order the new jets and the heat shield for it too. Thanks for the part number by the way erik.

I really appreciate your help guys, very knowledgable...
 
One more thing, when I change the jets, is it ok to re-use the gasket? The gasket is brand new from the re-build kit, so I wouldnt think it would matter right?

Thanks again
 
The jets and thick base gasket won't affect your non idle situation. The fuel bowl gasket, if blue neoprene, is meant to be re-useable.
 
From what I've found, a poor idle quality problem with a #7448 carb is often caused by a dirty metering block (the part between the fuel bowl and carb body). The block has many small internal passages and orifices in it. Any bit of gunk, deposits, dirt particles, etc. Can really mess it up. Aerosol carb cleaner and a compressed air blowgun are your friends in solving this matter.

I've also found that the cork sealing rings that go on the idle mixture needle-screws get brittle and crumbly after time. New ones are available, but can be somewhat difficult to track down.
 
Erik is exactly right about the ease with which these internal passages can become impeded by grit sucked from the fuel tank, especially if there are no filters in place, or from deposits left behind by moisture contamination and gummed up fuel in the bowl.

When you serviced this carb, was it completely torn down and the hard parts allowed to soak in a cleaning agent such as crc tyme parts soak? Just hosing it down with carb cleaner followed by a quick blast of compressed air at that stage isn't good enough. Sometimes the passages in those metering blocks get so munged up that the brass plugs have to be drilled out to allow better access for cleaning.

The other obvious thing going on with this carb that we've touched on briefly, but need to pursue further, is that none of the adjustments for good drivability appear to have been made. It seems that the carb was simply re-installed, fuel source re-connected, and thrown into service. Until the choke is fully functional, this engine will be an absolute bear to get started, especially this time of year. If the idle mixture screw settings are way out of whack, there's no way it will idle properly. If the idle speed adjustment screw is backed off to the point that its not actuating the throttle linkage, that too will prevent the engine from idling unassisted. There's just a shit ton going on with this carb that needs to be sorted through in a methodical manner.
 
Well, I found some time to mess with this puppy today and I did what you said to do scoutboy, I didnt mess with the backwards pivot arm yet, but I adjusted the needles on each side of the carb and did just like what you said, and the choke plate goes to a 45 degree angle, so it is not running flat across. I see that the electric choke has an adjustment on it. Do I need to look at that?

Brian
 
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