Mysterious Vacuum Hose, were to...?

[giantpune]

So as soon as needle moves from 0 on ported vac, I am at correct spot?

You want no vacuum on the ported port at idle.

 

[YellowHorse]

You want no vacuum on the ported port at idle.

Thanks, I read it wrong first time. No vac at idle on ported, and as soon as throtle is open just a tad, should see vac.

 

[YellowHorse]

Another issue I had was trans kickdown linkage was preventing carburetor to open past 45%. I massaged rod in to slightly different shape and took off a bolt on the carb kick down cam. Now cam on the carb does not start to engaging kick down linkage untill 45% open and fully engaged once carb is 100% open. Hope that's the right way to go about it.

Linkage has some resistance for carb to close all the way, so I had to increase tension on the return spring.
Last picture shows bolt on a cam which I took off, still there.

 

[giantpune]

I'm not familiar with your specific carb and transmission combination. Holley does sell an extension for the ford kickdown rod. This does in the gap between the kickdown rod and the carb in your last photo.

https://www.holley.com/products/fuel_systems/carburetor_components/brackets_and_linkage/parts/20-41

 

[Sheriff41]

Another issue I had was trans kickdown linkage was preventing carburetor to open past 45%. I massaged rod in to slightly different shape and took off a bolt on the carb kick down cam. Now cam on the carb does not start to engaging kick down linkage untill 45% open and fully engaged once carb is 100% open. Hope that's the right way to go about it.

Linkage has some resistance for carb to close all the way, so I had to increase tension on the return spring.
Last picture shows bolt on a cam which I took off, still there.

It's important to get your carb set up right as a baseline.

In the first picture is that a return spring going forward from the throttle linkage? If so, I suggest you remove that extra return spring, disconnect the throttle cable from the carb, and see if the cable positions even with the ball stud with the carb in the fully closed position. If it doesn't then you need to adjust your throttle cable bracket (the one that mounts to the intake and holds the throttle cable) so the opening in the throttle cable is even with the ball on the carb linkage. Once you do that and before you connect the cable to the ball stud check the relationship between the throttle wide open and the throttle cable making sure you have full travel from the cable to WOT. Once you do this you should not need the extra spring.

On carbs with universal linkage, I like to use this ball stud that fits in the large opening on the throttle linkage: https://www.amazon.com/gp/product/B078WJS5V6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
This allows the cable to be straight through the range of motion. I then align the cable to the ball stud making adjustments to the throttle cable bracket. You may need to elongate the bolt holes in the bracket to allow fore and aft adjustment rather than bending the bracket.

You will need a small return spring for your kickdown linkage to pull it forward when you let off the accelerator pedal.

 

[YellowHorse]

It's important to get your carb set up right as a baseline.

In the first picture is that a return spring going forward from the throttle linkage? If so, I suggest you remove that extra return spring, disconnect the throttle cable from the carb, and see if the cable positions even with the ball stud with the carb in the fully closed position. If it doesn't then you need to adjust your throttle cable bracket (the one that mounts to the intake and holds the throttle cable) so the opening in the throttle cable is even with the ball on the carb linkage. Once you do that and before you connect the cable to the ball stud check the relationship between the throttle wide open and the throttle cable making sure you have full travel from the cable to WOT. Once you do this you should not need the extra spring.

On carbs with universal linkage, I like to use this ball stud that fits in the large opening on the throttle linkage: https://www.amazon.com/gp/product/B078WJS5V6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
This allows the cable to be straight through the range of motion. I then align the cable to the ball stud making adjustments to the throttle cable bracket. You may need to elongate the bolt holes in the bracket to allow fore and aft adjustment rather than bending the bracket.

You will need a small return spring for your kickdown linkage to pull it forward when you let off the accelerator pedal.

I set to make sure throtle cable almost fully compressed when butterflied open.
When disconnect throtle cable extends past carb cam as it should (this way cable spring should close buterfly).
However my problem was kickdown linkage resisting closure of buterfly towards the end of the travel - I need extension.

 

[vintageman]

I set to make sure throtle cable almost fully compressed when butterflied open.
When disconnect throtle cable extends past carb cam as it should (this way cable spring should close buterfly).
However my problem was kickdown linkage resisting closure of buterfly towards the end of the travel - I need extension.

I actually have my throttle cable set this way also, when disconnected it is extended about a 1/2 inch forward of the ball connector. For the kick down linkage adapter/extender, I believe that is only used on a 4 barrel Holley. I have a 4 barrel Summit 750 that I have to use the extender on. My kick down does not bind up though and did not bind up when I had my 2 barrel Holley on previously. Not sure is a little more tweaking with the shape is required but someone with more knowledge on this will surely chime in. One more thing, in your last photo, it looks like the throttle cable has somewhat of a bow in it, kind of like the bracket at the manifold mounting point is too low, I had to add some washers under my mounting bracket to get a straight cable run without the bow. Good luck.

Tom

 

[Sheriff41]

I set to make sure throtle cable almost fully compressed when butterflied open.
When disconnect throtle cable extends past carb cam as it should (this way cable spring should close buterfly).
However my problem was kickdown linkage resisting closure of buterfly towards the end of the travel - I need extension.

That's good. I've just seen many set up with the throttle cable not allowing full travel of the linkage. Sorry I don't have any experience with the kickdown extension so I'll defer to those that have.

 

[YellowHorse]

It's important to get your carb set up right as a baseline.

In the first picture is that a return spring going forward from the throttle linkage? If so, I suggest you remove that extra return spring, disconnect the throttle cable from the carb, and see if the cable positions even with the ball stud with the carb in the fully closed position. If it doesn't then you need to adjust your throttle cable bracket (the one that mounts to the intake and holds the throttle cable) so the opening in the throttle cable is even with the ball on the carb linkage. Once you do that and before you connect the cable to the ball stud check the relationship between the throttle wide open and the throttle cable making sure you have full travel from the cable to WOT. Once you do this you should not need the extra spring.

On carbs with universal linkage, I like to use this ball stud that fits in the large opening on the throttle linkage: https://www.amazon.com/gp/product/B078WJS5V6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
This allows the cable to be straight through the range of motion. I then align the cable to the ball stud making adjustments to the throttle cable bracket. You may need to elongate the bolt holes in the bracket to allow fore and aft adjustment rather than bending the bracket.

You will need a small return spring for your kickdown linkage to pull it forward when you let off the accelerator pedal.

Thanks.
I am getting two kits which Holley makes 20-41 (extension) and 20-91 (spring and a cam with some limit bolts). At which point front spring cam be eliminated.
Also will need to straighten my throttle cable, as Vintageman pointed out.

 

[mrgmhale]

Thank you. Do you happen to have 1971 vacum to trans calibration?

The Forel vacuum schematics for engines (sis calibrations) did not begin to appear until 1973. But, Mustang Barn took the time to collect/create vacuum schematics for 1967 - 1972, and makes them available for free. With their approval and knowledge I combined all of their separate PFD files into a single PDF that is grouped by year, and sorted by engine. The drawings are sometimes a little crude, but for engine calibration purposes for 67-72 they are far better than a sharp stick in the eye. That file is attached to this post. I have also attached the 1973 Shop Manual Volume 6 excerpt that shows all the emission control systems for 1973 Mustangs, and also provides the vacuum calibrations for the 73 engines.

In reading your question it sounds like you wanted also how the auto transmission vacuum line is connected. Lucky for 71 and 72 Mustangs things are easy, where they have a single vacuum line leading to the transmission vacuum modulator valve. One end is connected to the port at the rear of the tranny modulator diaphragm. The other goes directly to intake manifold vacuum, typically to a large vacuum tee behind the carburetor (unpainted silver looking vacuum tee that screws into the intake manifold.

For 1973 things got a little more complex, as their auto trannies have a dual diaphragm vacuum modulator. There are two kinds of vacuum sent to the modulator, one is intake manifold vacuum, as with 71/72 Mustang engines. The other is ported vacuum used to also open the EGR valve. The two kinds of vacuum use different diameter vacuum hose, The larger internal diameter hose if for manifold vacuum, and it is attached to the vacuum tee behind the carburetor. The other is slightly smaller in internal diameter, and is plugged into a small, plastic tee in the same vacuum line leading to the EGR valve. There is yet another attached file that shows how the vacuum modulator hose routing is set up from the factory, using a 4 port tee screwed onto the firewall.

If you need more info or need photos let me know.

 

[mrgmhale]

I'd keep looking for more vacuum leaks. Spray carb cleaner around the base of the carb, you can also use an unlit propane torch. Idle will normally change when you find one.

It also seems you have the Holley on a stock iron intake. Normally they seal fine, but I'd pull the carb and check the condition of the gasket. The carb pre-heat passage is below it, and given I see a flimsy Holley gasket on there, it could have burned through and be pushing exhaust gasses into the intake.

View attachment 77940

I found what was a fairly small vacuum at the base of our 2v carburetor on a 73 Mustang 302 engine. What apparently happened is a prior owner had not properly tightened the carburetor mounting nuts, and the passenger front cornet of the carb had a little vacuum leak as a result. I had removed the carb for other reasons, and discovered that problem when I examined the base plate gasket. I have it pretty well displayed in a video I have at the 41:42 mm:ss time location in the video:

https://www.youtube.com/watch?v=U-ETjhRqUwQ

 

[RC92234]

I'd keep looking for more vacuum leaks. Spray carb cleaner around the base of the carb, you can also use an unlit propane torch. Idle will normally change when you find one.

It also seems you have the Holley on a stock iron intake. Normally they seal fine, but I'd pull the carb and check the condition of the gasket. The carb pre-heat passage is below it, and given I see a flimsy Holley gasket on there, it could have burned through and be pushing exhaust gasses into the intake.

View attachment 77940

That's exactly what was happening in my car. I didn't see how bad the gasket was until puling the carb for replacement. The part of the gasket near the top-left bore in your photo was burned away completely on the bore side. New gasket (had to find on eBay) and 4360 carb from a '77 Lincoln and the improvement was outstanding.

 

[rackerm]

You mean like this one! Crappy aluminum casting burned right thru the side. I thought I had a leaky gasket. I did not see it until I remove it. Also see how thin the inner wall is. Now I use only cast iron plates.

 

[Stanglover]

Watching Autorestomod video, he states to not use ported vac on the side of the carb, but instead use vac niple on the bottom of the carb...for vacuum advance. Do you all agree?

8.3 min in to it

NO!!

 

[Stanglover]

Late to the party as usual, but can I add my personal experience as I too have a Holley 670 S/A.
On my car, a 71 M code 4 speed manual, mild Melling cam and 10:1 pistons, it ran best on ported vacuum. It has no additions like A/C or any other vacuum robbers other than a power booster and air cleaner vacuum temp switch.
I did find it beneficial to block off the heat cross over passages from under the intake due to fuel vaporization and I also found it needed to thicker base plate because the front butterflies did stick in the ports, which were sized for the Autolite 4300 carb. My carb ran very rich out of the box and stank the garage up. A local tuning specialist drilled a 3/32" hole in each primary butterfly and that allowed the transfer slots to be set where they should be, square. No more stinky gas smell either. The front 3/8" port is for the PCV tube, the rear on for the booster, but in my case it is plugged as the booster is connected to the T off the manifold. All others unless needed should be capped off.
As for the distributor, it is the stock Autolite running Pertronix Ignitor II module and coil. It is curved by, in my case, welding and recutting the limit slot to .410" or a 10L slot which equals 20 degrees of crank timing. This allows the initial timing to be increased to 14-16 degrees, which Cleveland's seem to like. The springs I use are 1 original heavy set slightly loose and 1 Mr.Gasket 925D light spring set with light tension. This gives me near perfect timing throughout the rev range and all in at around 3000rpm.
There is a cheat for this IF your dist. has a 13L slot. By adding a small piece of NYLON tubing, that will limit the travel close to a 10L and get you close. You might need to fine tune the initial to find the sweet spot. Pic 2
I forgot to mention that I do not use the 3 port vac switch either as the vac canister is a single diaphragm, set at 4-6 degrees vac on top of the mechanical degrees.

 

[Bobby]

Since buying big blue from the member here, I finally took of intake filter to figure out why it runs 2k rpms at idle and hard to keep running while cold.

So the car has Holly 670 cfm street avenger Carb and what I found is that there are two vac lines not connected anywhere. Small line goes through firewall and thick line Ts off from intake plenum.

Am I right to assume that they need to be hooked up to the black canister ?
Also what's that canister is for?

To answer your last question. The vacuum canister is for your A/C-Heater. This canister has a reserve of vacuum in it. The plastic device on top is a check valve to prevent loss of vacuum. While driving normal with your A/C on or heat blowing on your legs, everything is dandy. If you suddenly hit the gas to pass someone for instance, the sudden loss of vacuum would cause the dampers in the A/C unit to default to the defrost vents and you would not have that nice cool air hitting you in the face until manifold vacuum is restored. The canister contains your reserve vacuum to keep the dampers in their current position so that you have that nice cool air in your face instead of cooling your windshield. The port that has no hose on it will need to plug into the vacuum tree mounted to the rear of the engine above the firewall.....or, if you have room, you can route it to the manifold vacuum tree on the intake.

 

[YellowHorse]

I opened um my Holly carb to check on floats, gaskets and set idle transition, set floats paralel the ceiling.
Float bowl does not tilt down much because a rubber nipple is propping it up - is it normal, or should I trim it?

Also there was a good amount of dust like build up which clean up with a dry tooth brush.

Lastly, balancing chanel (at least what my common sense makes of it) between throtle body openings had casting residue blocking most of the passage....last pic.

 

[Hemikiller]

Yes, trim the nipple off the pump diaphragm.

 

[YellowHorse]

Ok, I rebuilt carb with new gaskets, cleaned up fuel deposits, set fuel floats, adjusted idle screw to have transition slot square and adjusted secondary butterflies to slightly open to get idle at 900-100rpms when hot.
Also connected plug wires in correct order! Previous owner mechanic really was a tool.

Car starts now weayyyy easier and runs better....dont have to start it with gas to the floor lol, actualy no gas input at all.

Vacuum runs at 16
Timing looks to be around 20 at idle 1" - 1.25" away from 0, which I marked ).
How do you see exact timing? I have marked 0, should I mark different color what I am targeting?