Carb swap in pictures, Holley 2210 to 2300.

[jeffro]

Santa Claus came and gave me a new carburetor for Christmas.

There is a lot of information here about switching to the Holley 2300, but I've not seen a step by step tutorial, and despite the wealth of information we do have, there are some little things I found unaddressed. So I decided I'd try my hand at making a step by step tutorial. Here's what I've finished so far, I've got more pictures to take to finish it out but I was feeling inspired to post this after reading "Scout II heater housing rebuild" by toomanycars.

My old carb is likely very familiar to most everyone here. It's a Holley 2210 "Smogerator". I'm not a fan of these carbs, I'm pretty sure no-one really is. I do know quite a few guys that can make them run well, but I've found them to be very finicky and difficult. The 2300 swap promises a bit more power, better driveability, tunability and reliability. I've heard many times the problems with the 2210 start right from the beginning, it was designed from the outset with one primary goal, and that was to meet 50-state emissions requirements that came into force in the 70's. It's got all sorts of vacuum lines run all over the damn place, each one a potential source of problems. Other problems include a speed sensor that keeps the throttle open after you let off the gas, a somewhat cantankerous choke pull-off, and temperature sensors that also have the ability to adjust idle speed. I've also been told the power valve setup it has is poor, but I really can't speak from knowledge on that.

The Holley 2300 sounds like an advancement just by name alone, but in reality it's an older design carb. Older in this case is much better. Primarily sold for circle-track racing today, it was once a fairly common carburetor, and even part of high performance packages such as the Dodge "six-pack", which had three of them in a row. They come in 350CFM and 500CFM configurations. I've got the 350CFM model, it's model number 7448. Everything I've heard is that this is the best two-barrel carb for an IH v8. I know some guys that run the 500CFM units, but in every case I've heard it's taken some fiddling to get them working well. Both versions are not emissions legal for vehicles built after 1968 or so, but I'm emissions exempt. You should check to ensure you are as well, or be prepared to swap back and forth for inspections. Also, with a bit of tuning it really shouldn't be any worse on emissions than my old carb. In fact, since they're much easier to tune and keep in tune I suspect emissions will ultimately be better.

Here we go, this is how I got started. A box of goodies, a laptop full of instructions and a bit of space on my dining room table to inventory things.


Here's the new carb, wearing a jaunty top hat. With it sitting on the gasket and hanging off the table like this, I was able to check the operation, get familiar with the bits and pieces, and start to determine if any other parts would be needed.


The 2300 ships with an incorrect gasket for use on an IH. It'll work, but chances are you'll have problems with fuel boiling in the float bowl if you use the supplied gasket on the left, the gasket on the right is highly recommended for IH use. It's got a bit of duck bill there that will insulate the float bowl from the intake manifold.


So here's what we've got to work with under the hood on the passenger side of the Scout II. Lots of vacuum lines running everywhere. It's not the worst in the world (try a 3rd-generation twin-turbo RX7 sometime) but it's plenty obnoxious.


Driver's side. Little better over here.


Start by removing the air cleaner, it's simple enough. Unscrew the nut at the top, lift the air cleaner up and move over to the side. There is a large hose that connects it to the driver's side valve cover with something that looks like a PCV valve (it's not), you can remove this and remove the aircleaner assembly, or just move it over to the side like I have.


Since we're working the driver's side first, I'm going to remove this vacuum solenoid next. This box is the "brain" of the automatic throttle control system. When it receives vacuum, it keeps a spring loaded vacuum actuator thingie "closed". You can see it right in the middle of the picture above, it's yellowish in color and has a vacuum line coming off to the left side. The actuator pushes directly on the throttle lever. Essentially, this is used as an engine speed sensor, but from what I can tell by my vacuum routing diagram it can also receive (or not receive) vacuum signal from the temperature sensors (mine wasn't set up to do so).


The left fitting on the box:


Connected to this fitting on the carb, this is where it gets it's vacuum signal.


The bottom fitting on the box:


Connected to this fitting on the vacuum actuator, this is where it delivers vacuum signal to keep the throttle open in certain situation.


Then I worked on removing the EGR valve vacuum lines. I'm removing my EGR in this swap. You can see behind the EGR valve that I've also removed the hose for the brake booster from it's fitting on the intake manifold. This was simply to make working easier and because I planned on replacing it while here (you should be inspecting and replacing this hose at regular intervals, it's important!).


The sole vacuum line coming off the EGR routes to this heat sensor on the driver's side of the intake manifold. It's connected to the top fitting. This heat sensor sends vacuum to the EGR valve in certain situations to allow exhaust gasses into the intake.


Here the top line is now removed, and I'm going to follow the bottom vacuum line off the temp sensor and remove it from both ends.


Here's the other end, connected to the base of the carb on the passenger's side, this is where the heat sensor sources it's vacuum signal from.


Back on the driver's side I removed the throttle cable linkage (the nut is loosened in the picture):


And I also removed the return spring that attaches from the carb throttle arm to the intake manifold.


As I said, I'm removing my EGR during this exersize. But in order to do so I've got to remove this PCV hose first because it's in the way. It's hard as a rock and shatters with impact!


Two difficult to reach bolts at the base of the EGR valve and the EGR is gone. There is a bit of debate over whether this is beneficial or not, but I'm in favor of simplicity here. I don't and didn't have an EGR on my 401 pickup, and the lack of it didn't give me any problems. Regardless, I may restore the EGR at some point in the future if I feel it's absence is missed. Just remember to hook up the heat sensor on the driver's side to a full vacuum port on the new carb and then from the heat sensor to the EGR valve.


In removing the PCV hose, I managed to pull this vacuum fitting from the intake manifold. The PCV hose from the PCV valve was connected to this end. You can see the hole it once occupied just to the left of it.


I removed the large diameter hose here from the back of the carb. This has a T-fitting on the end and feeds my in-cab vacuum gauge and the other heat sensor. That heat sensor has no other vaccuum lines running out of it, the fittings on it are capped, so I'm sure it's not doing a damn thing except plugging the other end of the vacuum line. I'm going to use this end to feed vacuum to the aircleaner assembly heat sensor once we reinstall. I previously stole the aircleaner line for my in-cab vacuum gauge.


Then I removed the fuel line. This is pretty easy. Hold one nut while you turn the other.


Once the fuel line is off I pumped some of the gas out of the float bowl by operating this lever on the carb. This operates the pump shot, which is what pours fuel down the carb body when the gas pedal is stabbed. This function operates outside the the venturi and is designed to deal with sudden demands for fuel. Venturi on the other hand respond to airspeed, but airspeed won't increase immediately after suddenly opening the throttle. In fact the airspeed across the venturi drops initially. This is because then engine won't pull more air without more fuel, and the same volume of air will move slower through a larger opening than a smaller one. This is why you must have a pumpshot. The pumpshot takes care of the engine's demand for more fuel while the venturi catch-up, without it the engine will hesitate badly with sudden pedal movements.


Here's the throat of the carburetor. You can see the venturi. I tried like hell to get a shot of the pumpshot squirting fuel down the barrel, but I couldn't get my timing down. It was too hard to operate the lever and hold the camera and hold the choke open. You can see the area where the fuel from the pumpshot enters the barrels. It's a little sqaure notch at about 1:30 at the top of the barrel on the bottom there. The other barrel's notch is obscured. Incidentally, you can see how dirty this carb has gotten inside. I believe this is largely because of EGR.


Next it's time to remove the choke activation circuit. This is comprised of the fancy bent-up metal wire coming straight up from the intake manifold and is connected to the choke armature on the carb. Down on the intake manifold is a bi-metal spring. I'll show it in a few. At the top there is a little metal clip that can simply be pried off. Once the clip is removed the wire comes right out of the armature.


Looking down the wire we can see the bi-metal spring. The bi-metal spring is pretty cool, but we don't see them very often in automotive applications anymore. It's comprised of two types of metal laminated to each other. Because the two metals contract and expand at different rates, we can use the bi-metal spring to activate things based on temperature. This spring is normally covered with a little metal cover, but I've removed it so we can see. The cover just pulls off. The base of the housing the spring is held in is connected to the intake manifold by two hex-studs. I couldn't get them to back out, so I eventually removed the adjustment nut seen on the right side of the spring. This holds the spring to the housing base. I left the housing base there and replaced the cover. The spring and wire had to be removed because it cannot be used by the new carb and would likely interfere with the proper operation of it.


Now we can remove the carb itself. (Sorry, I got ahead of myself with this picture, the choke wire should be removed by now). There are four bolts holding the carb onto the intake manifold. Sometimes carbs are attached via nuts on studs, but this one is not.


With the bolts removed the carb just lifts off. It's likely some fuel will still leak out of it, try to keep it level to prevent this.


Here's the last vacuum line. It's connected under the float bowl and thus a little hard to get to. You could remove it earlier, but this way I can give a good picture. This line is connected to the carburetor's metered vacuum port, and is used to operate the vacuum advance on the distributor. Remove it now if you haven't already done so.


Now the carb is off. Set it somewhere and admire your work. Note there is still one vacuum line attached. This is the choke pull-off. It opens the choke up after the engine is started.


I'm pretty impressed with how dirty this unit is. It's supposed to be only 2 years from a fresh rebuild, and the truck sat for most of those two years. I'm thinking perhaps it's seen a bit more use than that, I've only put 3000 miles on it.


Now we pry off the old gasket, it came really easy.


And remove the old hard fuel line that connects to the carb from the fuel filter. The new carb accepts fuel in a different area, so we'll have to modify this hard line or build a new one. I think I may build a new one so I'll always have all the parts I need to go back to this setup.


This ends the removal phase of the carb swap. I'll post the installation phase in a little bit. My 2300 is on, but I've not gone through the pictures or wrote anything up yet. I can tell you this, the swap was so worth it. It was like driving a different truck once I was done. Easier starting, more power, better response, everything. I expected a difference, but I wasn't expecting it to be as good as it was.

[ihscoutlover]

Great writeup Jeff. Kinda like when I did the rear brakes on my Terra. Very detailed. Maybe we can get together and do one on the rebuild of these carbs. You shoot pics while I clean and build? JK. Very nice work, although you might want to edit the last one and advise of plugging the intake with a rag or something to prevent crud from getting down in there. Again great writeup and I look forwards to the install of the new carb.

Jeff

[Robert Bishop]

Looks like a lot of fun! I love to look at your pictures. It is cold where you are at in St. Louis. I used to live in Columbia, MO and remember the cold and snow.

Robert

[46binder]

Great pics, My 2210 is garbage, maybe I should get a 2300. Anyone have a used one good for rebuild?

[Catfish]

Fantastic attention to detail. I will definitely use this post in the future to help me install a new carb.

[Catfish]

Fantastic attention to detail. I will definitely use this post in the future to help me install a new carb.

[gary9202]

[jeffro]

Originally Posted by Robert Bishop

Looks like a lot of fun! I love to look at your pictures. It is cold where you are at in St. Louis. I used to live in Columbia, MO and remember the cold and snow.

Robert

Yeah, it was in the teens and snowing when I was doing this. Had to be pretty motivated. Keep moving, stay warm, go inside from time to time and drink some hot water.


Jeff, you don't see the intake covered because it wasn't open but for long enough to install the new gasket and carb. Good thing to do if you are planning on leaving it open for any length of time. As for a writeup on a carb rebuild, I'd do one one a 2210, but there are serveral really good writeups on that available here and at IHonlynorth's forums. I've seen some good stuff on the 2300 as well. So unless folks really like my writing style or something, I don't think I'm gonna do it. It's a lot of work putting one of these together. I'd say taking pictures, retaking pictures, redoing things because I forgot to take a picture of what I was doing and writing this up more than doubled the time it would take to do the job alone. That's why the install phase isn't completed, it got too damn cold and I just went into "get it done mode". Now I'm going to have to tear things down a bit to finish showing how to build it up.

[ihscoutlover]

I just figured pointing that out to newbies so that they don't end up with crud and nuts and parts and stuff in the intake where it doesn't belong. I have seen some of the mentioned builds, but I didn't recall seeing one on here. Either way yes you are correct it does take time to write and picture these. I plan on doing a writeup on Melissa's Traveler's front brakes when the weather breaks a little. Great job either way. Definately a good help to those who haven't done one of these before.

Jeff

[Tonebone]

Anxiously awaiting the install phase. I see it snows in your garage too. Tony