Rebuilding 2300 List 2977 Carb

[trenlong]

Ok so here we go,
I am tommorow going to pick up the generic holley service pack p/n 37-1543 and shall hopefully begin the process.
Any tips list or idears I should know to start with?
I will post pics tommorow once I get the parts together.
Thanks,
Tren

[Michael Mayben]

We'll hold yore hands Tren!

Main thing is to TAKE PICS and document your first effort, that way you KNOW what ya got along the way and can compare with stuff I have here for samples.

Do NOT attempt to remove either the choke butterfly or the throttle butterflies, though you do need to verify that the screws are extremely tight.

Remove the nylon accel pump cam from the throttle arm, noting which hole the screw is in, that cam needs to be carefully inspected as well as the actuator arm, for wear.

Many of the pints are covered in that 23XX thread also, especially the accel cam/arm interface.

Be sure to remove the accel discharge or "shooter, and carefully remove and set aside the check valve that is underneath the screw. There are THREE different checks used on these carbs, you MUST use the one that is correct for that main body.

Those kit instructions cover all variations of the 2300, not specifically your 2997. So use that info as a reference, it is NOT an absolute for your exact mixer.

You will prolly find all the throttle body and fuel bowl screws loose. That is a common "problem". When ya go back together with it we'll discuss how to handle that.

The accel pump well "check" in your carb will either be a small ball bearing encased by a retainer, or a orange silicone rubber "umbrella". The ball is captive, no service required as long as it's not corroded/stuck. The silicone check will be replaced with the new one in the kit.

The throttle body-to-main body gasket you select from the kit must be an EXACT match for the old gasket. EVERY noob has a problem with that, ask Trever and Drew! Any carb is a precision instrument, so you can't be too clean in your re-assembly techniques. Same for cleaning all parts. THAT is the difference between "works perfect" and "parts donor".

Here's copy of the worksheet I use for Holley modular carb service, works for either a 2V or a 4V carb. Record the important inspection points as you pull it down, then you will know what the setup on it is for future tuning!

[trenlong]

yea ok I think the carb is a bit to gone, after cleaning it for about 2 hours and an overnight bath in carb cleaner this is how it looks

So Michael can you give me a call so I can buy a carb from you???? Jeff has my number.
Thanks,
T

[Michael Mayben]

Yep...my initial thoughts are..."parts donor"!!!

Jeff and I discussed this REAL early this morning and what options he can make available for ya that will include COMPLETE "tech support" for getting you up and running! I work exclusively now with the Ismail boys regarding the carb stuff, and they supply me with a lotta Holley cores so we can keep this stuff going for the future.

So deal with Jeff, he'll tell me what to prep (I have the NEW 2300 centerhung kits Jeff and Chad introduced at the Binder Bee already assembled and ready to dropship with all needed mods already performed for IH stuff) and we'll fix ya up!

In the meantime...try and get that exhaust hooked up and coolant in the motor...ya won't be able to install and run any carb for more than 30 seconds until ya git those parts completed...even in a temporary fashion! Don't wanna risk makin' a cripple outta that fresh motor!

[trenlong]

Awesome,
I will call up Jeff now,
I did get the exhuast hooked up last night.
one step closer, I am getting desperate to get this thing together!!! its been three years=)
t

[trenlong]

Ok well with a bit of luck and junk yard love I came up with this!!
Its a list 2977 of a 304 engine.








So disassemble and bath in carb cleaner?
Thanks,
Tren

[Michael Mayben]

That's a "previously re-manned" carb done by Holley, thus the white mylar sticker. While it's "based" onna 2997 core, it may not have been built as a 2997 replacement, I don't have the data to convert that number under the bar code to an actual LIST number. But that should not be a problem as far as matching the carb to your motor.

The manual choke appears to be complete, that is a carb that can not be converted to any other type choke system, so you will need to rig a choke bowden cable in the dash.

Two bad someone painted an engine with the carb attached! The carb cleaner/dip I use will strip that paint right off.

That vacuum fitting has been added and is a really bogus piece of plumbing! Remember, a true 2997 would NOT have a vacuum "ported" vacuum port in that location that is active. That tells me the metering block does not match the main body. The proper metering body for a 2997 will have p/n 4275 stamped into the top of it right hand side as looking at the fuel bowl, partially hidden by the air horn.

Just plug that vacuum port and try it and see what happens.

Go for it!

[trenlong]

Hi,
Yea that paint job is sweet!!! it is getting a bath right now, are there any of the gaskets that I shouldnt use out of the holley kit? I know you said there were some discrepancies with some of the gaskets.
if I block of the vacume advance what do I hook up the advance on my dist to?
thanks,
tren

[Michael Mayben]

Use the gaskets from the kit that match the removed gaskets exactly. If you have a concern or can't decide, then post a pic of ALL gaskets and I'll point to the right one. Lay 'em on the bench and mark which is which with a number.

In fact, if it's disassembled now, layout ALL original parts out onna clean white towel and take some shots. Then I can tell what to use from the kit. And I need to see the accel pump portion of the metering block also.

You can run the vac advance from a manifold vac point, such as that "open" hose barb for the wipers we talked about last week. But that is only if the wipers are now electric. Don't run from manifold vac if you are gonna use the vacuum pump built into the fuel pump. 266/304 motors ran from manifold vacuum up until about '66 or '67 models, maybe '68?

WE may need to go into the vacuum port analysis deeper when ya get the parts sterile. We'll use compressed air, carb cleaner, and common sense to "trace" the vacuum passage (and ALL passages in the metering block, main body, and throttle body.

[trenlong]

Ok so here is where we are at:
With some help from my brother who is a much better mechanic than I we managed to tear it down, clean is up and get it back together. All of the gaskets were perfect fits so there was no worries there. It went back together with out any problems and did not leak a bit... so on to the photos







So onto the questions:!!
Where is the fuel/air mixture screw?

roughly how many turns out?

vacume port for the vacume advance on the bottom plate is the right one?

It doesnt seem like it firing on all cylinders I am going to pull out the spark plugs to see if they have fouled or something

I was trying to time it with a timing gun but was not getting a consitent flash of light could it be I am not getting a clean reading on spark because them big ole plug wires are too thick?

how tight does is the accelerator pump supposed to be at?

what rpm do we time it at?

The engine did fire and run pretty well but not that well and I think its the carb...
Thanks Michael!
Tren

[Michael Mayben]

Got sum coffee down tha gullet, let's see if I can be coherent...

Here's how to verify the "ported" vacuum passage in that metering block/main body/throttle body:

First blow carb cleaner/air through the port on the metering body and see where it exits. Be careful, DON'T blow that shit in yore eyeball, it'll burn for at least an hour! Use a Sharpie to mark the hole!

Then "match" the hole on the main body and do the same. Note where the passage exits the main body.

Then find the corresponding port on the throttle body and repeat one more time.

IF the passage leads to a position in the main body/throttle body which is ABOVE the throttle butterflies, then that is a "ported" or "timed" vacuum source. When running at idle, you should see somewhere between 0.0"Hg and 5.0"Hg on the vacuum gauge when connected to that fitting.

If the passage leads to a point BELOW the throttle butterflies, then it's a MANIFOLD vacuum source, and when running at idle, that port will show whatever manifold vacuum the motor can develop.

That port on the metering block "should" be a ported source. But someone could have scruud with it, that is why we want to verify so we can tune it in properly.

Also, what is the p/n on the metering block for YOUR 2997 carb...an original metering block does NOT have that port drilled through, therefore it's "dead", a blank hole when you look inside.

The brass vacuum nipple in the 2997 throttle body is MANIFOLD vacuum, it leads to a point BELOW the throttle butterflies! That is how you remember the difference, pretty simple, no juju and you can ALWAYS figgr that out yourself on any carb!

In your pic, you have NOT installed the two idle mixture screws (with springs) in the throttle body. The tips of those screws should be CLEAN and not have a definite "ring" showing resulting from over-tightening at some point in the past. Set those two screws 2 turns out from seated for a starter.

For now, connect your vacuum gauge to that port and keep it there for tuning, we'll need some numbers from that position until it's all dialed in!

After ya report back your finding on the ported vacuum trace, then we'll deal with that. But for now, just cap that port on the metering block and DO NOT connect the distributor vacuum cannister to anything.

If it's not firing on all cylinders, it's possible ONE SIDE of the metering block is still clogged. Look at that carb as TWO separate carbs that share a common fuel supply bowl. The passenger side venturi supplies cylinders #2, 3, 5, 8. Driver side venturi supplies #1, 4, 6, and 7. That is a "medium rise/dual plane" manifold setup. I also need to know what the main jet numbers are, and VERIFY they both are the SAME number! The main jets supply ALL liquid fuel to the metering system, even for the idle circuit so if the mains are not right, nothing else will be either!

"Typical" main jets (OEM) inna 2997 are #51>#53.

If the idle/pullover circuits on one side are still clogged/restricted, then it ain't gonna run on four cylinders (it's actually running but EXTREMELY lean, resulting inna "lean misfire which is random). That makes ya "think" it's an ignition issue,when in actuality it's a carb/fuel delivery issue.

For accel pump "adjustment", look at that thread here where we worked with Dan in Denver on his centerhung 2300, the process is exactly the same. And ya GOTTA make sure the accel pump lever where it rides on the nylon cam is smooth, pics are in that thread. And I need to know WHAT COLOR cam ya have and WHAT HOLE the screw is in! The OEM cam for that carb will be "white" though yours may appear to be a mungee-lookin' "tan" or whatever. CORRECT cam color (thus profile) is CRITICAL for these carbs to work properly onna SV application...MOST important!

For where you are at right now, I never hookup a timing light, just time it initially "by ear". But any 304/345 will run OK somewhere between 6* and 8* initial timing, prolly end up with more once it's dialed in.

IF the timing light is NOT flashing steadily at EVERY fire point for #8, then you may have an ignition issue, could be way retarded or way advanced. Just hit a middle point and see what's happening. Retarded will make a "spit back" through the carb, advanced means it cranks over hard likea dead battery and it tries to "kick back" when it fires (can break the starter drive).

Your inductive pickup timing light "sees" an induced electromagnetic pulse every time the plug fires for that cylinder. It's physically IMPOSSIBLE to "insulate" against a magnetic flux field, therefore the thickness of the insulation of the plug cable has nothing to do with whether the light can pulse or not. But some cheezeball timing lights with an inductive pickup can't trigger reliably from some "spiral-wound" RFI suppression cables. Try placing the pickup on another position on the cable or another cable just to see if you can get any reliable/consistent flash. And an inductive pickup is polarity-sensitive, make certain it's clamped on the cable the proper direction and the jaws close COMPLETELY! Them high-zoot plug cables with the overlay heat protection for the DUI can create issues with cheezeball timing lights.

Don't get discouraged, no doubt you still have multiple issues to work through one atta time. And you are dealing with an UNKNOWN carb that is your FIRST attempt at servicing. So far ya done real guud, but we gotta go through all this stuff one step atta time!

DON'T connect the vacuum to the distributor UNTIL we figgr everything out. Don't wanna create additional problems. Once it's perfect...I'll explain why the "ported" vacuum deal (and the advice to disconnect it for timing purposes) is bogus, even in the IH service references!

[trenlong]

When I dismantled the carb there was two gaskets between between metering body and main carb body. The rebuild kit only came with one gasket. When I put it back together I only used one gasket and had fuel leaking out screw that holds it all together right above the accelerator pump. I put it back together again with 2 gaskets and it slowed the leak down substantially but its still leaking slowly.
The metering body number is 4275 for what that is worth.
The cam color on the accel lever someone sprayed the carb with spray paint and I am still trying to get through it to find the color.

I am working on getting a vacume gauge because we dont have one, but for now we should be ok not using one because we are just going to block both vacume ports off for inital tuning right.

The fuel jets are 53

When the carb is running I can see fuel squirt in when I use the accelerator pump and also at idle, it makes me seem to think I dont have a clog but as I am new to this I am not really sure.
Thanks,
Tren

[Michael Mayben]

TWO metering body-to-main body gaskets??? THAT's bogus! That means someone in the past drove a screwdriver between the two parts to "separate" 'em and cut through the sealing projection in the zinc casting! NO leak is to be tolerated, in addition to being a hazard, that will be both a "metering" fuel leak AND a vacuum leak depending upon where it's boogered. Ya CANNOT seal this stuff with any type adhesive, it will simply not work. The "blue" gaskets are a composite paper material treated with a neoprene surface treatment to enhance sealing yet not "stick" like the older brown or black gaskets. I have more than a few carb bodies and metering blocks ruined in that same fashion!

Do what ya have to to make that area seal with only a single gasket, two gaskets totally upsets the relationship between the components.

Just because the accel pump circuit "squirts, evenly, doesn't mean the metering block is sealing and is free-flowing for both venturis. The accel pump "shooter" for both venturis draws from the single accel pump/check valve/reservoir. That is a test of ONLY the accel pump circuit.

Even a cheepo vacuum gauge is fine for doing this. It tells ya MUCH about what is going on!

Spray carb cleaner on the accel pump cam to clean it, rub the stuff in real well. The cam is nylon, the carb spray won't hurt it at all. The paint will rub right off.

#53 jets are GOOD, don't scruu with those other than to make CERTAIN they are tight.

[trenlong]

yea ok
the carb wins I lose/
I just bought one from you guys... I suck at carbs. We cant get this sucker not to leak...
thanks,
tren

[Michael Mayben]

You gave up too easy dude! But then at least ya kept tha cashflow goin' the right direction!