2f cylinders one and two are not helping... (1 Viewer)

[Cruiser_GT]

The carb is a 1976.

The vac fitting at the top front of carb needs to connect to the manifold vacuum fitting right in front of the carb.

The choke breaker needs to connect to the vac fitting in the side of the insulator underneath carb (phillips head plug).

Need pics of hose connection at dissy and valve cover side of carb.

Jim - Here are the pics you requested. Thanks for the connection data thus far.

And you haven't even made fun of me yet... except I did believe this was the stock '78 carb. Long story, but I know why I was mistaken.

Thanks!

 

[Cruiser_GT]

Jim - No problem doing the relo for the carb breaker to the intake manifold (phillips). But, I'm confused on the front connection... Like, I can't find a port in the front of the carb... here's a pick after the relo... the only port that is close is the vac advance coming off the valve cover side (I said that for myself... I know you know exactly where and what that is).

Appreciate the help...

As a side note... what tipped you to the fact that this was a '76 carb? Also, is the '76 carb using vac retard rather than advance?

Thanks again.

 

[Nomis]

Also, is the '76 carb using vac retard rather than advance?

Vac. advance.

 

[Cruiser_GT]

Check the thing that's labeled as #45 in this picture (credit: SOR). It's one of the few places where a massive vac leak could affect cylinders 1-3.

Mr. Toad - I really wasn't thinking specifically about 1-3 being affected directly by a specific vacuum leak. I've been focused on ensuring that the desmog was connected correctly and that any leaks were plugged.

Have you got a pic that might tip me as to exactly where I might find the emission gas filter?

Currently I'm workng to this schematic...

https://forum.ih8mud.com/showthread.php?t=121581

Unfortunately, my carb is a bit different from the one shown.

thanks

 

[Fuzzy Logic]

Are you sure your idle solenoid is working properly

 

[Mr. Toad]

Mr. Toad - I really wasn't thinking specifically about 1-3 being affected directly by a specific vacuum leak. I've been focused on ensuring that the desmog was connected correctly and that any leaks were plugged.

Have you got a pic that might tip me as to exactly where I might find the emission gas filter?

Sure. It screws into the top of the intake manifold on the same side of the carb as cylinders 1-3. Since yours has been desmogged, look for where someone might have replaced it with a plug. Here's another SOR pic that shows where it ought to be:

Here's why I made that suggestion: There are relatively few problems that would only affect certain cylinders, especially where the affected cylinders are on the same side of the engine (front rather than rear). Doesn't sound electrical, so look at fuel and air. Plus, many times I have seen vacuum leaks caused by a faulty brake booster. The symptoms are nearly identical to what you describe, except that the affected cylinders are #s 5 and 6 instead of #s 1-3. With a big vacuum leak in the brake booster, you can pull the spark plug wires off #5, #6, or #s 5 AND 6 at idle and the engine continues to run as it had before you pulled the wires. If you then re-attach the plug wires and plug the manifold port that feeds the brake booster, the RPMs kick up about 200 RPM. The reason it affects only certain cylinders is that the booster draws vacuum off of the intake runner that feeds cylinders 5 and 6.

Since your problem is with cylinders 1-3, I looked for a place where a vacuum leak would likely only affect those cylinders, and I only came up with the vacuum fitting referenced above. It's an easy one to check, and if that's not it, move along and look for that rodent nest in the intake, inop valves, or blown head gasket.

Good luck

 

[Cruiser_GT]

Mr. Toad - Found it. It is plugged, but I will verify that it is plugged well. Thanks.

 

[FJ40Jim]

I'm confused on the front connection... Like, I can't find a port in the front of the carb... here's a pic after the relo... the only port that is close is the vac advance coming off the valve cover side (I said that for myself... I know you know exactly where and what that is).

The power valve port on the top of the carb should be connected to the manifold vac filter in front of the carb, the big hex thing. But yours has had the one or two plastic vac nipples broken off.

You could get a vacuum tee fitting and splice into the hose you just connected to the manifold spacer block.

As a side note... what tipped you to the fact that this was a '76 carb?

It has external PV, but no AAP.

Also, is the '76 carb using vac retard rather than advance?

The carb isn't using anything, It is just a source of ported vacuum signal. The distributor can be either vac retard or advance. Yours is actually both, but you have it hooked up correctly w/ vac only going to the advance fitting.

 

[Cruiser_GT]

Okay... I think all the vacuum lines are connected correctly. Still have not replaced the base gasket for the carb. I just hate to order a $2 part... so I'm waiting on that until I figure out the vacuum advance on the dizzy... the real purpose of this post.

Here's my problem. The corrosion is widespread. It took a bit of tapping to get the end of the diaphragm shaft to come free. In the pic below I am pointing out the location of a c-clip that I removed thinking it was holding the diaphragm shaft in place. I figure it has a purpose of holding the connector thing (attachs to the breaker plate) and would actually advance the timing when the diaphragm gets vacuum... what I'm getting at is this... should that thing free-float on the shaft?

Also, I can't find anything in the FSM about setting up the diaphragm. Looks like it has less than a quarter of an inch in travel. Is there a spec for how much travel is required?

thanks!

 

[FJ40Jim]

Put the c-clip back. It goes there for a reason.

The vac advance only moves the pickup plate appx 10 degrees. That's about .100" of travel.

PS: did you know there is no "base gasket" for the carb? There is a layer of gasket material permanently bonded to the top & bottom of the carb insulator block, but it is good for the life of the truck, unless somebody tears it up w/ a scraper. In that situation, the proper fix is a new insulator plate.

 

[Cruiser_GT]

Put the c-clip back. It goes there for a reason.

The vac advance only moves the pickup plate appx 10 degrees. That's about .100" of travel.

PS: did you know there is no "base gasket" for the carb? There is a layer of gasket material permanently bonded to the top & bottom of the carb insulator block, but it is good for the life of the truck, unless somebody tears it up w/ a scraper. In that situation, the proper fix is a new insulator plate.

C-clip will go back on. I figured it was there for a reason . I just wondered what that reason was? Perhaps it is only used in the initial setup of shaft... heck, I suppose the spring has a purpose as well, but I don't see that it has a role once all the pieces are assembled. Looks like the diaphram shaft moves back and forth rotating the braker plate a very small amount.

I left the mechanism drenched in penetrating lub last night and viola, I can make it actuate today by providing suction on the vac advance port. I still need more work on cleaning up all the corrosion inside the dizzy to ensure that the breaker plate moves freely as well.

The pic below (taken from SOR) shows #91 (plenum gasket)... I figured that it fit below the insulator. Since I have a vac leak at the base then per your guidance I will replace the insulator. It appears that this can only be purchased as part of the rebuild kit. Would you verify this for me?

I've read enough of your posts to know you are one of the most knowledgable folks out here concerning carbs and dizzys. Please forgive my ignorance and continue providing anything that you think I need to be aware of. I thought of PM'ng directly, but figured this thread might help someone else down the line.

I think I understand now how the diaphram works. My problem was that last night the thing would not accuate without using my hands to move the parts... it took way more than the 5 inches or so vacuum. Now that it is working, I will continue with the cleanup.

 

[FJ40Jim]

The gasket material that is permanently bonded to the insulator plate is plainly visible in the photo (the light colored material). The gaskets shown (#90 & 91) are aftermarket band-aids not supposed to be there.

 

[Cruiser_GT]

Thanks Jim.

 

[Cruiser_GT]

Update - Finally got the vac advance working on the LC. I also advanced the timing just a bit and adjusted the idle.

Running pretty well. Still fighting the vac leak at the carb base.

Also, for those of you that felt this idle problem was idle solenoid related... I checked it out by turning the ignition on and listening for the click. It is alive! Thanks for the idea.

Any ideas on a temporary fix for my vac leak at the carb? I was thinking about runnning a bead of rtv around the leaky side

 

[cruiser88]

Update - Finally got the vac advance working on the LC. I also advanced the timing just a bit and adjusted the idle.

Running pretty well. Still fighting the vac leak at the carb base.

Also, for those of you that felt this idle problem was idle solenoid related... I checked it out by turning the ignition on and listening for the click. It is alive! Thanks for the idea.

Any ideas on a temporary fix for my vac leak at the carb? I was thinking about runnning a bead of rtv around the leaky side

you can try it.dont know how long it will last. just a little

 

[Mr. Toad]

Well?

 

[Cruiser_GT]

LOL!

Caught me being a little lazy there Toad. Actually, I used the rtv and it sealed up the leak. A Singer never ran smoother than my 2f. Set the idel per spec and I mean it runs great. 2f's and I'm sure f's have got to be one of the smoothest engines of their day.

My gaskets came in today, but I'm away and won't get the carb reset until Thursday.

All this work and part replacement when the problem was simply a vacuum leak at the carb base. Well, other than the corrosion in the dizzy that had the vac advance hosed. I guess everything needed to be replaced and updated anyway... so all is not lost.


Thanks for the followup. I'll post a note to close this out after I pull the carb and re-seal it.

EDIT: I connected the vac as Jim recommended since I am missing the port that you pointed out.

 

[grant5127]

godspeed! bama...

 

[D'Animal]

Glad everything worked out.

 

[Mr. Toad]

Good to hear it's running well.