46 Guests, 0 Users

Author Topic: Cheep way to adjust fuel mixture with holly webber 5200  (Read 367 times)

0 Members and 1 Guest are viewing this topic.

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Cheep way to adjust fuel mixture with holly webber 5200
« on: December 09, 2019, 06:31:59 PM »
As some of you all know i built an intake kanifold for 2 SU carburetors awhile back

It ran great but i decided to do some redesign and temporarily fitted the stock holley webber 5200 2hich ran like crap..

Ive been doing some research and did some mods on the linkage as I described in another post.

With the SU carbs the engine ran easily up to 6000 plus rpm and had great torque but gas mileage suffered.

With the 5200 it hardly got up to 4500 and ran really rough and strained at 4000 plus.

The carb was a "rebuilt" one fitted by the previous owner

I checked the jets and discovered that when the carb was "rebuilt" the primary and secondary main and air bleed jets were both swapped.

To.complicate things there are 3 different measuring systems used to designate jet s8zes for the 5200, flow rate, micron and thousands inch hile diameters.

Here are some jet size comparisons i found

103 cc/min=105 microns, or 41.34 thou
128 cc/min=110 microns, or 43.31 thou*
152 cc/min=115 microns, or 45.28 thou*
178 cc/min=120 microns, or 47.24 thou*
201 cc/min=125 microns, or 49.21 thou*
225 cc/min=130 microns, or 51.18 thou
2 51 cc/min=135 microns, or 53.15 thou
275 cc/min=140 microns, or 55.12 thou
298 cc/min=145 microns, or 57.09 thou
325 cc/min=150 microns, or 59.06 thou*
346 cc/min=155 microns, or 61.02 thou
375 cc/min=160 microns, or 62.99 thou
400 cc/min=165 microns, or 64.96 thou*
425 cc/min=170 microns, or 66.93 thou*
450 cc/min=175 microns, or 68.90 thou*
475 cc/min=180 microns, or 70.87 thou
525 cc/min=185 microns, or 72.83 thou*

Fuel flow is controlled by a combination 9f the main jets in the bowl.and air bleeds or compensators.

 main jets in the bowl meter gas to venturies and gas and diluted by air  bleeds or "compensators" at 5he top to lean mixture.

Bigger mains = rich

Bigger bleeds = lean.

Basic theory

Run primaries with large mains large bleeds

Secondaries smaller jets smaller bleeds

Sounds backwards but thats how they work.

Sp3cs from an international harvestor website with 4 and 6 cyl engines.


4 cylinder
Primary Main Jet 140
Secondary Main Jet 140
Primary Air Corrector Jet 170
Secondary Air Corrector Jet 160
Primary Idle Jet 060
Secondary Idle Jet 050
Pump Jet 050

6 cylinder
Primary Main Jet 160
Secondary Main Jet 160
Primary Air Corrector Jet 190
Secondary Air Corrector Jet 180
Primary Idle Jet 075
Secondary Idle Jet 065
Pump Jet 060

Since The carb is supposed to have about 140 micron main jets in the primary and secondary and 170-160 micron jets in the air bleeds.

Mine were way small and had a small one in primay side and large in secondary.

Well i researched sources for jets and got really confused and couldnt make any sense of the sellers and supposedly the jets cost like $8 apiece or $32 for a set which may or may not work.

SOOO...

All the "experts" on webbers say that you shouldnt drill the jets which i sorta agree with but since i couldnt find jets so  i decided to drill.

I also installed a cheep narrrow band fuel air meter..
Air fuel gauge doesnt have numbers but looks like an oil pressure gauge with a rotating needle. If you assume that the scale went from 0 to 100 Supposedly "optimum" mix would be at 50 max lean at 0 and max rich was at 100

I sawpped the primary and secondary jets and Performance improved dramatically with jets in proper holes but Gas mileage was about 10-12 20 highway and gauge stayed at 85, sometimes dropped to 60

So i decided to enlarge the primary air bleeds to.lean the primary mix.

I got a set of "metric" drills from amazone and found that in the set there were about 5 s8zed from .060 to .070

So i selected a middle sized on  probably about .065 or so for the primary air bleed and drilled.

Well it turns out that the enlarged hile was too big and the mix was too lean, car bucked and bogged.

Gauge read 85 at idle but dropped to about 20-30 at hard acceperation indicating lean.

Hmm how to reduce the size of the air bleed.. cant make the hole smaller. but you can obstruct it to reduce the flow.

So.. i cut about an inch of 24 gauge wire from an ethernet cable, stripped the insulation, bent a piece into  a "U" shape and stuck it into the primary air bleed see pix.

Car ran strong but gauge indicated rich once more, always around 60 -80 just a little rich.

I then used a single wire inserted into the primary air bleed and now car runs good not great but gauge reads 85 at idelllle and cruise, 30-40 at hard acceleration in secondaries, pulls to .6000 good good but not great torque so I suppose the mixture is about right.

See attached photo.

Will.check the mileage and update.

Bottom line.. air bleed.size seems very critical.since the addition of a thin wire can affect the mixture a lot..

But good news is that if you need to play with the jetting just drill the bleeds a bit oversixlze and add some wires to fich up the mixture till you get the performance you want.

A lot cheeper than buying jets at $32 a pop.

Btw..I also noticed that the booster venturies were l99se so i removed them applied superglue to them reinstalled andmpeened them in.




Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Wittsend

  • Pinto Master
  • *****
  • Posts: 2224
  • FeedBack: +241/-0

  • Total Badges: 8
    Badges: (View All)
    Tenth year Anniversary Mobile User Topic Starter Poll Voter 1000 Posts Linux User Windows User Fifth year Anniversary
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #1 on: December 10, 2019, 03:02:03 PM »
Interesting, "Tuning by Wire." It is actually an interesting prospect. Sort of like the rods in Carter/Edelbrock/SU carbs (granted not tapered).

  I have soldered up holes in jets and then drilled them to a specific size. Not sure if it holds long term. But if there is any breakdown of the soldier..., well, you are getting a lead additive.

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #2 on: December 10, 2019, 03:12:33 PM »
Maybe there is hope for making these carbs work..

Found an interesting article on modding the 5200 for racing

http://www.thelolaregistry.com/DIY/Weber.htm

I also found a boxed set of 150 metric drill bits that include  in sizes from 1.10 to 2.0 in increments of .01 mm along with smaller and larger ones on amazon

https://www.amazon.com/Unxuey-Precision-Drilling-Plastic-0-4mm-3-2mm/dp/B07T2YGB8B

These correspond to the weber jet sizes

1.20 = 120
1.40 = 140 etc

Meanwhile Im cutting new runners for the redesigned manifold for the 2 Su carbs.

Hopefully Ill get it finished soon
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline pinto_one

  • Pinto Master
  • *****
  • Posts: 1001
  • FeedBack: +70/-0
  • Gender: Male
  • Pinto-One

  • Total Badges: 10
    Badges: (View All)
    1000 Posts Photographer Tenth year Anniversary Topic Starter Signature Poll Voter Mobile User Apple User Windows User Fifth year Anniversary
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #3 on: December 13, 2019, 09:18:08 AM »
Good info on the old webber 5200 , Make note that the later copys 5210 and newer are diffrent , the older one were 270 CFM and newer (or Last ) ones were 235 CFM and the jets were maker for flow , I remember working on these when a pinto owner would come into the ford dealer with problems with the carb , yes they were always were just cleaned up with a carb kit installed , yep the air bleed jets and tubes were always in the wrong place and jets also , and somtimes the idle jet was missing ,  more offten when the carb was put togather wrong it is always put back wrong , just to let eveyone know that when you do take one of these apart write down the numbers of each number of the jets and bleeds and where they go , Thanks for Long Time Ford Man digging up this long lost info ,
76 Pinto sedan V6 , 79 pinto cruiser wagon V6 soon to be diesel or 4.0

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #4 on: December 13, 2019, 09:37:08 AM »
You re welcome..

My car is sort of a test platform.as i am always tinkering with it to try to make small improvements for reliability, performance and wxonomy without major mods.

Interesting that you have found incorrectly installed jets as well.

Wonder if they were that way from the factry or switched during a "rebuild"?

Mine also had a mix of size designations so i dont really know what size they are.

As i mentioned i found a set of mertic drills 1-2 mm on amazon that comen in a box that has marked storage spaces.

I plan to paint the shanks of the drills with paint matching the resistor color codes, 1.10= black 1.2= brown 1.3= red etc so i can use them as size gauges for the future.

Will post info about fuel mileage when i have a few milles on the current config.

Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #5 on: December 13, 2019, 07:16:46 PM »
Update on 5200 ca4b jetting

Well i installed an air /fuel meter "AFM" to check the mixture.

I had a bung welded into the exhaust pipe about 2 ft downstream from the junction with the exhaust manifold and installed a cheep Bosch 3 wire heated O2 sensor.

This unit opuputs 0-1 volts depending on the mixture. 0 = lean 9= rich.

Actually a pretty flat curve from 17:1 to 15:1 then  the voltage rised to a max of about .9 volts at about 14:1 to 10:1 see attached graph.

I used a gauge from amazon

https://www.amazon.com/ESUPPORT-52mm-Fuel-Ratio-Gauge/dp/B00SMJ0BTQ

And compared readings from O2 sensor between gauge and a digital voltmeter and saw that the gauge is linear from 0 to .9 v and matched the viltmeter.  Midpoint of .5 v is straight up and indicates about 14.5:1 ratio.

So the entire range of the meter matches the working range of the sensor about 14:1 to 16:1 pretty much the ideal range so if you have a very rich or lean condition the meter would probably go off scale.

with my current jetting the engine idles at about .8v or about 14.3:1
Cruise varies from .6-.8v

Sudden throttle open and voltage drops to about .3-.5 v still  close to optimum mix.

I will measure the  current jets and post info about the sizes as soon as i have time.

If anyone is interested in installing a AFM gauge i woud recommend this one.

The gauge has 3 wires

Red power for illumination,
Green for signal from O2 sensor
Black for ground for both illumination and signal.

O2 sensor has 3 wires one for power to heater it  it uses about 4 amps

One ground for heater usually the heater wires are the same color and signal is differen.

One for signal

BUT make sure that you run a ground wire from the exhaust pipe to the gauge otherwise the reading wont be correct.

Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #6 on: December 17, 2019, 09:50:15 PM »
Ongoing saga of holley 5200 jet search

Welll..

After  numerous partially successful experiments with drilling the nets and using wires to resize them J decided to drill the main jets to 1.4 mm (140 microns) and use the approx 165-170 airbleed in the primary and redrill the secondary to approx 160

This resulted in a lean mix and bog.

SOOO..

I kept the 140 main jets and moved the 160 to the primary and filled the secondary with solder and redrilled it to about 140 ish.

This c9mbination seems.to.run pretty well, not great but engine gets to.6000 in first and 55oo in second, minimal bog at 1700 in 4th

Noticeable transitions between idle, main and secondary stages.

AFR gauge reads about 14.5 -15 ratio

Not sure about the mileage yet

So i guess this is about as good as the 5200 will get.

Definitely about 2/3 the torque of the SUs and not nearly as smooth

Also.takes a lot more pedal to.cruise at 50-70 mph

Drivable but i am eager to get the  new manifold for the SUs welded up and get them back on
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Wittsend

  • Pinto Master
  • *****
  • Posts: 2224
  • FeedBack: +241/-0

  • Total Badges: 8
    Badges: (View All)
    Tenth year Anniversary Mobile User Topic Starter Poll Voter 1000 Posts Linux User Windows User Fifth year Anniversary
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #7 on: December 18, 2019, 02:14:18 PM »
It is always a tough call whether it is 'Holley spent mega $$$ on research and who are we to know better' and, 'these carbs were set up for a poor smog control situation and certainly that can be improved upon.'

The nice thing about SU's is they are so easy to fiddle with. Different viscosity in the damper..., a few twist of the main jet position. On the other side when you start getting to different taper needles, and hand sanded needles that get just as complicated as any carb.

I love the EFI in my Turbo Pinto. 31 year old engine in a 46 year old car, it sits for months and starts at the turn of a key.

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
New thoughts..
« Reply #8 on: December 20, 2019, 02:05:27 PM »
Testing the latest jet combination i discovered that a similar condition still exists, rich during idle and cruise and lean durning hard accelleration causing a momentary hesitation.

Opposite of the ideal.situatio n of lean cruise and rich accelleration.

It occurred to me that i connected the crankcase vent with the stock PCV valve to the intake manifold as per factory stock setup.

Thinking about that i realized that under high vacuum conditions ie idle.and cruise the valve is closed allowing the carburetor to determine fuel mixture

BUT at low vacuum during sudden acceleration the manifold vacuum drops and the valve opens to allow a sudden rush of unc9ntrolled and uncarburetated air into the intake manifold leaning the mixture.valve.

I also have the breather tube from the oil filler cap tk the air cleaner connected so i am going to try to block off the vacuum port to the intake manifold for the crankcase vent and as well the v3nt from the crankcase .

In theory that way the only air entering the intake manifold should be a controlled mixture from the carburetor.

Any ideas?
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline pinto_one

  • Pinto Master
  • *****
  • Posts: 1001
  • FeedBack: +70/-0
  • Gender: Male
  • Pinto-One

  • Total Badges: 10
    Badges: (View All)
    1000 Posts Photographer Tenth year Anniversary Topic Starter Signature Poll Voter Mobile User Apple User Windows User Fifth year Anniversary
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #9 on: December 25, 2019, 08:21:49 AM »
I would leave the PVC valve set up the way it is , but make sure you have a good name brand valve , seen some fit all copys that will bleed to much ait and mess up the idiel ,  next is to make sure you have the right well tubes , the ones under the air bleeds , some were stamped with diffrent numbers , easy to get swaped in the wrong hole , from what I can remember the number is stamped on the end , last you can narrow the adjustment down by disconecting the linkage to the secondary , just run one barrel and tune , you will always get the best MPG out of of it because carb works its best wide open , last is do you have the exhaust heat to carb hooked up ??
76 Pinto sedan V6 , 79 pinto cruiser wagon V6 soon to be diesel or 4.0

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 371
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Cheep way to adjust fuel mixture with holly webber 5200
« Reply #10 on: December 25, 2019, 08:32:06 AM »
Actually i finally connected the pcv  valve as per factory the carb has a hot water heater in the manifold.

I put 140 main jets and 150 air bleeds in both primary and secondary that produced good torque to 6000 with secondary opening at about half throttle

I checked the well tubes didnt see any numbers from the top and couldnt remove them but the one with the larger bore was in the primary side.

Did an 80 mile test run on flat road with speed between 50 and 70, mostly 55 to 65

Refilled tank and it took about 3.2 gallons for about 24.7 mpg so i figured that was good.

Am now doing an around town test for 100 miles to check that mileage as well.
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles