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View Full Version : 2F Carb questions, help needed


MDH33
07-22-2007, 01:48 PM
I have a 2F carb I'm rebuilding with date code 9 L 5 (Dec '69 ?). I need the float height adjustment measurements and I don't have a FSM for this year. Also, how should I set the air/fuel adjustment screw when re-installing (how many turns from bottomed ?).

Any help greatly appreciated.

:thumb: :beer:

Edit: it's a '69 2bbl carb not a '79 as I originally posted

treerootCO
07-22-2007, 01:50 PM
Turn and a half

MDH33
07-22-2007, 01:56 PM
thanks mike, do you have a FSM for a 79 2F carb thatwould have those float height measurements?

Edit: it's a '69 2bbl

treerootCO
07-22-2007, 02:10 PM
All my FSMs are in my dad's Cruiser and, you know, I can't have Cruisers at my place anymore......

subzali
07-22-2007, 06:28 PM
I've heard 2 1/2 turns...mine didn't run with any less than that anyway.

Haynes says: Raised (from air horn fitting surface) .161 in
Lowered (between needle valve push pin and float tab) .039 in

MDH33
07-22-2007, 07:20 PM
Thanks Mike and Matt.

Matts float height specs match up with Jim C's that he posted on MUD so that's what I went with and it looks good, fuel is right at the dot in the sight glass.

The idle problem is still persisiting after a full carb rebuild and I replaced all the vacuum lines that remain and tightened up the PCV valve line as well because it seemed to have a slight leak.

I'm stumped. :confused: It will idle with a tiny bit of choke, but with no choke it stalls at idle.

I still need to do a valve adjust. Could this possibly be the culprit??

treerootCO
07-22-2007, 08:23 PM
you have a vacuum leak. As I learned from my dad's cruiser, the leak could be internal.

Rzeppa
07-23-2007, 07:27 PM
Yep, needing some choke is most often a vacuum leak. Somewhere. Unfortunately, a fully smogged 79 has a LOT of places for vacuum leak. Start simple (hoses fallen off, cracked, nuts holding the carb on not torqued) then work your way up. Spraying carb cleaner at suspect spots to check for a change in idle RPMS is a time honored method.

BTW, I also start with 1.5 turns on the idle mixture screw, then work one way or the other by ear. Usually it wants a bit more CCW, but not always. Every cruiser is different. Float level should make no difference to idle unless it's WAY off.

Oh yeah...make sure the idle solenoid cutoff is opening when ignition power is applied :-)

MDH33
07-24-2007, 09:14 AM
I searched for external vacuum leaks and found none, although this has been desmogged and the few remaining lines may not be connected correctly...

So, i tried about three turns out on the mixture screw and it's idling, but not well.

I have another question about adjusting the carb: On the linkage side of the carb facing the firewall (see pic) there are what appears to be two idle adjustment screws. One is horizontal and points towards the drivers side, the other is above that and angles up towards the passenger side. Can anyone explain their function and how I am supposed to adjust? Thanks!

http://www.sor.com/shared/image/042/042-01D-1.jpg

treerootCO
07-24-2007, 09:31 AM
fast idle and slow idle.

:D

subzali
07-24-2007, 11:48 AM
instructions on MUD too.

MDH33
07-24-2007, 12:08 PM
fast idle and slow idle.

:D

Smart@ss :lmao:

MDH33
07-24-2007, 01:03 PM
instructions on MUD too.

I have read every post on MUD I could find. Unfortunately they all have a lot of talk about adjusting this and turning that, vacuum gauge, :blah: but no pics or references to my specific carb. Most are also talking about later model carbs. Mine appears to be a '69 model. I have yet to find a single picture or diagram and my headache is compounded by a de-smog job that could be botched...

just want this darn thing to run.

Rzeppa
07-24-2007, 05:30 PM
The fast and slow idle screws are pretty obvious as to which is which if you look closely. The regular (slow) idle stops the throttle plate linkage when the choke is not engaged, the end of the fast idle screw only touches anything when the choke is engaged.

I have a couple of spare ~70-72 vintage carbs you're welcome to borrow to dink around with if you want. They look like proper vintage from the photo and also from recollection of what fits what (this is a 72, right?).

Other than a vacuum leak, you may still have some kind of obstruction in the idle circuit preventing proper fuel flow. I can't remember, does it run okay now at higher throttle settings and loads than idle? IOW, is it crappy across the board or just at idle? Idle-only kind of narrows it down; that's when the idle circuit is the only section metering fuel, and also when vacuum is highest just below the throttle plate except when going down a hill with the throttle closed.

Are there any backfires?

What do the plugs look like?

MDH33
07-25-2007, 08:13 AM
Thanks for the reply Jeff.

Your explanation of the fast ans slow idle made things clear.

It runs great as long as I'm on the throttle a little, or if I have the choke out a hair.

I am still wondering about my vacuum lines. It's desmogged, but the VSV is still in place and there are several vacuum lines that are capped off. Four total coming out of the carb:

Two on the valve cover side. One is capped and the other is going to the distributer. Two on the drivers side, one going to the throttle body and one to the carb Diaphragm.

Anyone know how these should be connected? I'll get some pics this morning and post them up.

MDH33
07-25-2007, 09:56 AM
ok, i have a couple of pics showing the vacuum lines on this carb:

this one shows the three lines coming from the VSV. one goes to the manifold, one goes to the throttle body and one to the carb diaphragm.

http://mdhuber.smugmug.com/photos/176916018-L.jpg

next picture shows the opposite side of the carb and the vacuum line coming from the distributer to the throttle body. The other line is capped.

http://mdhuber.smugmug.com/photos/176916132-L.jpg

Does this look right, or is there a better way that I could connect it?

thanks.

subzali
07-25-2007, 11:58 AM
Don't know about most of those, but of the top of my head the dizzy one is correct.

MDH33
07-25-2007, 12:40 PM
Don't know about most of those, but of the top of my head the dizzy one is correct.

I added some labels to drivers side pic. Not sure if I have these vacuum lines from manifold and vsv correct:

http://mdhuber.smugmug.com/photos/176959492-L.jpg

Rzeppa
07-25-2007, 05:09 PM
Okay, that manifold doohicky is a thermal vacuum switch and doesn't do anything in that setup. The one to the "carb diaphragm" is suspect IMHO. Without having the emissions manual in front of me, I suspect the diaphragm you refer to is the choke breaker. The choke breaker is supposed to see full manifold vacuum ALL the time and shouldn't go through the VSV. The function is when the choke is fully closed, it opens it a crack as soon as the engine fires so the engine has at least a little air to run with.

In the previous photo with the line to the distributor, those lines look suspect too, depending on the distributor. If you have a "non-USA" or early distributor with vacuum advance, or a 1978-up with vacuum advance, the plugged off one abve the throttle plate should go to the distributor advance. In a stock 1969-1977 configuration, the distributor is a retard and should be controlled by the VSV in a fully smogged rig. I'm pretty sure the top one is the "ported" vacuum just above the throttle plate and the bottom one is probably full manifold vacuum; not 100% sure on that, but again, a stock 1969-up will have the dizzy going through the VSV and not direct to the carb. It is okay for a early-1968 or a 1978-up dizzy to connect to ported carb vacuum, bypassing the VSV, that's what you want for a desmogged rig.

The line with the check valve from the VSV to the charcoal canister looks correct, but IIRC there should be more than one from the VSV to the canister. Not being an expert in the 1973 model year canister or it's connections, that's just from later model canisters.

What's the line on the VSV on the lower left? Is that capped off or is that an open fitting or...?

Side note: I love the "Front" embossing on the brake master :-) Like you couldn't figure out which end was which? LOL!

wesintl
07-26-2007, 12:00 PM
You are not fully desmogged. Why do you have spaghetti going to the vsv? I would bag that little box entirely

MDH33
07-26-2007, 12:17 PM
You are not fully desmogged. Why do you have spaghetti going to the vsv? I would bag that little box entirely

My thoughts too, but I'm still not sure what to re-route and what I can eliminate.

If I'm understanding it correctly, I think that i can run a vacuum line from the choke breaker/carb diaphragm down to the inlet below on the DS throttle body, which should give full vacuum.

Eliminate the lines from the gas filter on the manifold.

disconnect the charcoal canister tube from the VSV and connect it to the air filter housing near the carb.

Sound like it would work?

wesintl
07-26-2007, 12:25 PM
I believe so. I'm trying to think how my 76 is..

you should have the one line from the dist to the carb and a line from the carb to the carb and close off the inlet on the intake..

MDH33
07-26-2007, 01:43 PM
I believe so. I'm trying to think how my 76 is..

you should have the one line from the dist to the carb and a line from the carb to the carb and close off the inlet on the intake..


cool :cool: I'll give it a try. Thanks! :thumb: