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Discussion Starter · #1 ·
Hello all,

While not a HotRod by any means, my 53 Packard is having some issues and I figured with the knowledge on this forum, I think I just might be able to get this figured out. Hopefully you all are willing to help a dude get his Packard back on the road.

So, here is the story. I picked up a 53 Packard last year that had been sitting for 30ish years. I had the tank gone through, installed all new fuel line, fuel filter, electric transfer pump, installed a recently rebuilt mechanical fuel pump, rebuilt the carb, new base gaskets and carb insulator, new battery, new plugs, wires, vacuum advance, all new vacuum lines.

When I rebuilt the carb (Carter 4bbl), it was SUPER out of spec. I'm surprised it ran at all when it was parked. Anywho, I rebuilt it and adjusted everything per the factory manual. I'm super OCD and have rebuilt many carbs before, so I feel pretty confident in the rebuild (but ya never know, maybe I missed something).

When I first got her fired up, she had a pretty gnarly miss at idle. A neighbor told me it probably had a stuck valve or lifter and to put MMO in her. So, I replaced 20% of oil with MMO per their instructions. After driving her a few times in the last week or two, something definitely freed up because she idles a lot better now.

I've got her to the point where she starts up relatively easy, idles well enough, and gets down the road okay. The problem I'm having is a weird lean (I think) area if I slowly wind it up with no load on her. When I get to about 25-30% throttle, the carb makes a gnarly sucking sound and wants to die. If I push past it, the accelerator pump squirts fuel and she revs up great. If I rev her up real fast from idle, she revs up great and this issue doesn't show up at all.

The weird thing is, if I partially cover up the primary side of the carb and slowly wind it up, she continues to raise in RPM and sounds fine. I don't know if I'm covering up a vacuum leak or creating better vacuum because the engine might still have stuck valves or rings causing low compression.

When I cruise, it seems to be around this lean area and the car just doesn't seem very happy when cruising around. I have to kind of accelerate and let off over and over. It sucks to say the least.

What do you all think? Am I fighting a carb issue, vacuum leak, or low compression not pulling the charge in?

Thanks fellas,

-Chris
 

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Discussion Starter · #3 ·
I’d add a few degrees to the base timing to see if the area you encounter is one of those places where the ignition advance is not keeping up with the needs of the engine.

Bogie
Hey Bogie, Thanks for the reply. I did what you suggested yesterday and nothing changed. I'm starting to wonder if maybe I didn't clean the air bleed passages well enough. Maybe they're clogged up.

-Chris
 

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Probably there is a gap in the transitions that occur between the idle circuit, transition circuit and main metering. Could be dirt, gums, varnishes or corrosion inside the passages. The WCFB is a pretty primitive carb with a mixture of materials. The modern carb cleaners are not really up to the task of removing this stuff.

You might try retarding the timing as well to force more throttle opening at idle.

A common problem on these old cars is the heat crossover under the intake gets plugged up with carbon and ceases vaporizing the dribbling fuel, this makes the engine behave as if were lean while fouling the plugs as if it were rich. A crutch can be to adjust the choke so it doesn’t fully open to force main metering to come in sooner than the lazy air flow through the venturi’s do. Another is to raise the float level so it takes less signal to initiate fuel flow from the primary venturi‘s.

With old carbs and ignitions your into a whole new world of tuning exercises that you will find solve one problem while creating others, you just have to find the compromises you can live with it’s not anything like modern cars that read and interpret sensor data and adjust the tune on the fly for you.

Modern fuel is blended for fuel injection as it has been for almost 30 years, it kind of sort of works with carburetors, but never all that well, but one has to remember that these points distributors and early carbs and spark plugs never went more than 10,000 miles between major tune ups and had a few screw adjustment touches between the big tune ups. Basically before the coming in the later 1950’s of modern carburetors like the Holley end bowel, the Carter AFB, and the Rochester 2 and 4G series carbs were woefully inadequate. Then the points ignition system was never very good nor long lasting. This was the way things were till electronic ignitions of the late 1960’s early 70’s. Back then every city intersection had 4 gas stations with a working garage and independent garages in between all with more business that they could handle. Back in 1956 the interstate highway system was just a gleam in Eisenhower’s eye. Being from a transcontinental family I have a lot of Route 66 and US-99 and 101 time as viewed from the back seat of a 49 Plymouth station wagon I shared with my forever car sick younger brother. So I‘m not just talking historical automotive theory. Getting a car to a hundred thousand miles without a major engine rebuild, but would include at least one valve job, back then was call for all the neighborhood men to come and ogle the miracle. And I’m not even talking about chassis lubrication on thousand mile intervals, oil and filter changes ever 2500 miles, cleaning and recapping spark plugs as required between 10,000 mile replacements, brakes that hardly met the definition, etc. So when someone you know that is under 60 years of age starts pining for high-octane leaded gas and oil stiff with ZDDP, just shake your head an walk away, for they know not of what they speak.

As for you and the Packard, sit back in your mind’s eye and enjoy the ride into automotive history. Forget about the modern mantra of tuning Holley’s with air bleeds, it’s nonsense as applies to WCFB’s (Will Carter Four Barrel) just in case you didn’t know what it means. And Will Carter had long before been ousted from president of the company he founded by the time the WCFB was designed as he thought carburetors not about corporate finances so the money grubbers tossed him. But naming the modern for the time carburetor after him was a nice gesture and didn’t add any cost burden to the investor class.

Bogie
 

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Discussion Starter · #5 ·
Probably there is a gap in the transitions that occur between the idle circuit, transition circuit and main metering. Could be dirt, gums, varnishes or corrosion inside the passages. The WCFB is a pretty primitive carb with a mixture of materials. The modern carb cleaners are not really up to the task of removing this stuff.

You might try retarding the timing as well to force more throttle opening at idle.

A common problem on these old cars is the heat crossover under the in take gets plugged up with carbon and ceases vaporizing the dribbling fuel, this makes the engine behave as if were lean while fouling the plugs as if it were rich. A crutch can be to adjust the choke so it doesn’t fully open to force main metering to come in sooner than the lazy air flow through the venturi’s do. Another is to raise the float level so it takes less signal to initiate fuel flow from the primary venturi‘s.

With old carbs and ignitions your into a whole new world of tuning exercises that you will find solve one problem while creating others, you just have to find the compromises you can live with it’s not anything like modern cars that read and interpret sensor data and adjust the tune on the fly for you.

Modern fuel is blended for fuel injection as it has been for almost 30 years, it kind of sort of works with carburetors, but never all that well, but one has to remember that these points distributors and early carbs and spark plugs never went more than 10,000 miles between major tune ups and had a few screw adjustment touches between the big tune ups. Basically before the coming in the later 1950’s of modern carburetors like the Holley end bowel, the Carter AFB, and the Rochester 2 and 4G series carbs were woefully inadequate. Then the points ignition system was never very good nor long lasting. This was the way things were till electronic ignitions of the late 1960’s early 70’s. Back then every city intersection had 4 gas stations with a working garage and independent garages in between all with more business that they could handle. Back in 1956 the interstate highway system was just a gleam in Eisenhower’s eye. Being from a transcontinental family I have a lot of Route 66 and US-99 and 101 time as viewed from the back seat of a 49 Plymouth station wagon I shared with my forever car sick younger brother. So I‘m not just talking historical automotive theory. Getting a car to a hundred thousand miles without a major engine rebuild, but would include at least one valve job, back then was call for all the neighborhood men to come and ogle the miracle. And I’m not even talking about chassis lubrication on thousand mile intervals, oil and filter changes ever 2500 miles, cleaning and recapping spark plugs as required between 10,000 mile replacements, brakes that hardly met the definition, etc. So when someone you know that is under 60 years of age starts pining for high-octane leaded gas and oil stiff with ZDDP, just shake your head an walk away, for they know not of what they speak.

As for you and the Packard, sit back in your mind’s eye and enjoy the ride into automotive history. Forget about the modern mantra of tuning Holley’s with air bleeds, it’s nonsense as applies to WCFB’s (Will Carter Four Barrel) just in case you didn’t know what it means. And Will Carter had long before been ousted from president of the company he founded by the time the WCFB was designed as he thought carburetors not about corporate finances so the money grubbers tossed him. But naming the modern for the time carburetor after him was a nice gesture and didn’t add any cost burden to the investor class.

Bogie
Hi Bogie,

I apologize for the late reply.

Since writing my original post, I pulled the carb off, tore it part and blew the crap of it to make sure that all the air bleeds and small passages were cleaned out. Unfortuanly, when I put everything back together, the problem still persists.

I also did a cold compression test with the throttle and choke wide open. Here are the results:

1 = 125
2 = 115
3 = 115
4 = 120
5 = 125
6 = 120
7 = 125
8 = 115

The numbers look to be pretty even, but they appear to be a little on the low side.

I haven't checked the vacuum at idle yet because I don't know of a way to test it without unplugging the vacuum advance. There is only one vacuum port and its for the hardline going to the dizzy.

I took your advice and retarded the timing a little at idle. She does sounds a little happier and seems to rev up a little cleaner as well.

By heat crossover, do you mean the heat riser in the exhaust manifold? The flapper door setup?

If I adjust the choke so it doesn't fully open, wouldn't that make every circuit run way richer?

Thank you for the help and all the great info, I super appreciate it.

-Chris
 

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Discussion Starter · #6 ·
Just checked the vacuum at idle. She was sitting around 19 inches of vacuum initially, then I played with the enrichment screws and got her up to 20 inches. I also recorded the issue at hand. Here is the link:


-Chris
 

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I would check the accelerator pump linkage. Maybe it does not start to shoot gas soon enough with a small throttle movement off idle. There may be slack in the linkage. Maybe the fill port under the accelerator pump piston is to exposed. I am not familiar with this type of carburetor but this seems to be a universal problem and happens with other type of carburetors as well.

Engine sounds very good and idle vacuum is excellent.
I am assuming this is a flathead and the compression is good for a standard flathead. I would think that as you use it the cylinders may even out some but the test is good. Remember this engine had leaded gas in 53. like bogie said, back in the 50's you needed a valve job at 50,000 miles. Everyone did it. This engine may have some lead deposits in the valve seats causing the compression test differences.
Just drive it! I would say there are many more miles on this engine.

how about a picture of the car?
 

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The intake is connected to an exhaust passage in the head’s that supply hot exhaust to a chamber under the plenum. The heat riser flapper gore in one of the exhaust manifolds or head pipes is designed to be closed when the engine is cold so all the exhaust on that side is forced through the intake exhaust crossover.

Two things happen with these thins one is the crossover passage gets clogged with carbon so it no longer works at all. The other is the flapper door fails closed forcing that side’s exhaust to always exit through the heat passage under the intake.p, which might be clogged.

The effects can be from no heat at all to vaporize the liquid fuel and even up the cylinder to cylinder AFR’s or too so hot the mixture is thinned and fried by the time it gets to the cylinders.

This is just something to add to your list of possibilities not necessarily the answer to your problem but something needing to be checked out.

Your compression numbers are a bit low but are reasonable both as standalone per cylinder and to the variation be cylinder.

Bogie
 

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When I cruise, it seems to be around this lean area and the car just doesn't seem very happy when cruising around. I have to kind of accelerate and let off over and over. It sucks to say the least.
JMHO, this sounds like lean surge, it is probably exiting the transition circuit and entering the primary circuit which is lean, I would richen the primary a little by changing the metering rod or jet.
 

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I "ll be watching , I have never worked on a wcfb, My grandson 17 yr old is going to finish a T bucket project I started several years ago , 350-350 with dual WCFB carbs. Engine is a mild reuild stock bore , polished crank bronze valve guides an Hyd flat tappet cam.
 

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My 65 corvette (327 & 250 HP) has WCFB with 1 size up on main jets according to my notes. There is a meter rod positioning. It’s been years (approx 30) since I had to do anything to the WCFB (knock on wood) I had saved this from some web site.

Mechanical Operation of Metering Rods
During part throttle (high vacuum) operation, the position of the metering rods is controlled by the metering rod arm attached to the pump countershaft (Fig. 5-C). Mechanical positioning of the rods is required to prevent fuel starvation as under high vacuum conditions the vacuum pull completely overcomes the vacumeter piston spring tension and the metering rods would fully close the metering rod jets.
Vacuum Operation of Metering Rods
When vacuum pull is less than the tension of the vacumeter piston spring, the metering rods (Fig. 5-C) are moved toward their "wide open" position. Low vacuum occurs during acceleration, hill climb ing, and other engine load conditions. As the engine load decreases, manifold vacuum increases until once again mechanical metering rod action takes place.
 

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Discussion Starter · #12 ·
I would check the accelerator pump linkage. Maybe it does not start to shoot gas soon enough with a small throttle movement off idle. There may be slack in the linkage. Maybe the fill port under the accelerator pump piston is to exposed. I am not familiar with this type of carburetor but this seems to be a universal problem and happens with other type of carburetors as well.

Engine sounds very good and idle vacuum is excellent.
I am assuming this is a flathead and the compression is good for a standard flathead. I would think that as you use it the cylinders may even out some but the test is good. Remember this engine had leaded gas in 53. like bogie said, back in the 50's you needed a valve job at 50,000 miles. Everyone did it. This engine may have some lead deposits in the valve seats causing the compression test differences.
Just drive it! I would say there are many more miles on this engine.

how about a picture of the car?
The accelerator circuit is working great. This issue happens during a no load cruise, or when reaching a certain RPM (don't know what it is because I don't have a tach) after slowing opening the throttle.

Awesome! That's great to hear. She still has a pretty gnarly lifter tick, but hopefully that'll eventually go away. And you're right, it is a flathead.

Haha! Will do! Hopefully that's the case.

Thank you,

-Chris

Here is the picture!
 

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Discussion Starter · #13 ·
The intake is connected to an exhaust passage in the head’s that supply hot exhaust to a chamber under the plenum. The heat riser flapper gore in one of the exhaust manifolds or head pipes is designed to be closed when the engine is cold so all the exhaust on that side is forced through the intake exhaust crossover.

Two things happen with these thins one is the crossover passage gets clogged with carbon so it no longer works at all. The other is the flapper door fails closed forcing that side’s exhaust to always exit through the heat passage under the intake.p, which might be clogged.

The effects can be from no heat at all to vaporize the liquid fuel and even up the cylinder to cylinder AFR’s or too so hot the mixture is thinned and fried by the time it gets to the cylinders.

This is just something to add to your list of possibilities not necessarily the answer to your problem but something needing to be checked out.

Your compression numbers are a bit low but are reasonable both as standalone per cylinder and to the variation be cylinder.

Bogie
Ah, okay. I know my door is loose, but the thermostatic spring is indeed missing. There is a weight from the factory that keeps it open I believe if the spring has failed. I'll investigate it further though just incase.

Okay cool, that's good to know about the compression.

Thank you,

-Chris
 

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Discussion Starter · #14 ·
JMHO, this sounds like lean surge, it is probably exiting the transition circuit and entering the primary circuit which is lean, I would richen the primary a little by changing the metering rod or jet.
That's exactly what it is. The only problem with doing that, is that I'd be covering up the issue at hand. This is the stock carb on a stock engine. There has to be a reason this issue is happening.

-Chris
 

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Discussion Starter · #15 ·
My 65 corvette (327 & 250 HP) has WCFB with 1 size up on main jets according to my notes. There is a meter rod positioning. It’s been years (approx 30) since I had to do anything to the WCFB (knock on wood) I had saved this from some web site.

Mechanical Operation of Metering Rods
During part throttle (high vacuum) operation, the position of the metering rods is controlled by the metering rod arm attached to the pump countershaft (Fig. 5-C). Mechanical positioning of the rods is required to prevent fuel starvation as under high vacuum conditions the vacuum pull completely overcomes the vacumeter piston spring tension and the metering rods would fully close the metering rod jets.
Vacuum Operation of Metering Rods
When vacuum pull is less than the tension of the vacumeter piston spring, the metering rods (Fig. 5-C) are moved toward their "wide open" position. Low vacuum occurs during acceleration, hill climb ing, and other engine load conditions. As the engine load decreases, manifold vacuum increases until once again mechanical metering rod action takes place.
Thanks for those notes, I super appreciate it. As of now, I'd rather not adjust anything outside of the factory specs because I feel like I'd be covering up the issue at hand, but it sounds like I may be able to raise the metering rods a tiny bit to get more fuel in these no load conditions if I do decide to go that route.

Thanks again!

-Chris
 

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Discussion Starter · #16 ·
UPDATE:

I installed a manual choke yesterday so I can start driving this old girl until I figure out what's going on. When the lean surging happens during cruise, the only way she's happy is when the choke is FULLY CLOSED. We were cruising about 40 mph (don't know RPM) and she was happy as a clam.

Obviously something is up. That means she must be getting air from somewhere right? How is it possible that she has a vacuum leak that big only during a certain RPM range?

At idle there are no signs of any vacuum leaks. She idles at a nice low rpm and the enrichment screws will get her to die if turned in all the way.

Anyone have any ideas?

-Chris
 

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It's been 50 some years since I've messed with a WCFB, had a pair of them on a sbc in a 36 Ford coupe, but I seem to emember the floats are a ***** to adjust. My though is the metering rods could be sticking and/or the floats are set too low.
 

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Ditto what ntfday says above, floats may be too low or fuel pump not keeping up.
There is also the possibility the primary and secondary jets are reversed, the larger jets go up front with the metering rods in them. A lot of people confuse this and install the smaller jets up front. This often results in the metering rods shutting the fuel off in the small jets.
 

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Discussion Starter · #19 ·
It's been 50 some years since I've messed with a WCFB, had a pair of them on a sbc in a 36 Ford coupe, but I seem to emember the floats are a * to adjust. My though is the metering rods could be sticking and/or the floats are set too low.
I could be wrong, but I don't think the metering rods are likely to stick because they are pulled up mechanically by the tab on that top shaft. The one that also operates the accelerator pump.

The floats are set per the factory specs in the manual, so I don't think the problem is there either.

-Chris
 

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Discussion Starter · #20 ·
Ditto what ntfday says above, floats may be too low or fuel pump not keeping up.
There is also the possibility the primary and secondary jets are reversed, the larger jets go up front with the metering rods in them. A lot of people confuse this and install the smaller jets up front. This often results in the metering rods shutting the fuel off in the small jets.
The floats are set correctly. Any higher and I'm sure the fuel would start to flow over. I had thought about the mechanical pump maybe not keeping up, but this issue still happens even when I run my electric transfer pump.

I knew of the bigger jets going up front and the small ones going to the rear prior to rebuilding the carb, but I'm not going to lie, I've been starting to question whether or not I actually did that or not. I should have checked them the other day when I had the carb apart. I'm almost 100% sure I did it correctly because I made reminder notes to follow when reassembling the carb. Also, it's my understanding that the rods wouldn't even fit in the small jets, and if they did, they wouldn't allow almost any fuel to flow. I could obviously be wrong though, it's just what I've read.

-Chris
 
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