PINTO CAR CLUB of AMERICA
Welcome to FordPinto.com, The home of the PCCA => General Help- Ask the Experts... => Topic started by: jeremysdad on August 21, 2013, 12:08:56 PM
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Reading about the Holley 5200 around the internet, I have come across info that the famous 5200 Pinto flat spot is quite likely a too-small primary idle jet.
I remember swapping mine from primary to secondary and vice-versa last year when I was trying to limp it on 2.5 cylinders, but can't remember if I swapped them back.
Can someone with an early 2.0 look at their primary idle jet and tell me what size it is? They're the large brass screws toward the top of the carb, one on the driver (primary) and one on the pass (secondary) side.
Thanks, guys and gals! :)
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The flat spot can commonly be caused by less than adequate accelerator pump shot too. If you can turn idle set screw both in and out and motor runs rougher either way then you are big enough on the idle jet. Pay particular attention to when you screw it OUT, or CCW direction. The lean out, or CW shows up more obvious than the over-richen, lean out will die but too rich may just get rough and not die. If you get rough going rich with screw then you're right as far as idle jet size. The richness will show up less on later models since they started necking back on the hole to hit idle emission specs.
You can always drill the hole bigger but you can't go back after doing so. I used to pick up extra idle fuel and air jets out of the junkyard just to have tuning parts. Pump shooters too.
If the carb has been set up to where the throttle blades are deep in the transfer slots or holes then your flat spot too, they should be set so that the blade or butterfly just begins to expose hole or slot there. The slots/holes act as miniature accelerator pumps themselves, if already exposed then no more fuel addition possible when the throttle is cracked open, and again the flat spot.
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I found my flat spot last night when I pulled the idle jets to check while installing my shiney new K&N breather assembly. There was a tendril of teflon tape covering the hole in the end of the primary idle jet. Who knows...cleane d the passage with carb cleaner, and voila, purring like a kitten. :) After researching, the larger idle jet goes in the primary side, which seems contrary from an American mindset, but it works when you consider that the main circuit doesn't come into play until 3000 rpm or so. Info sourced directly from Weber.
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Because the main idle feed hole with adjustable needle is up front. The back only needs a small hole to feed the transfer only, no curb idle hole in back. The transfer need a little bit of feed so that it is active when the back barrel first cracks open, the transfer is the accelerator pump there. Like regular Holley 4 bbl., the back gets less idle flow.
It can get wonky sometimes though. When they start searching to lower emissions they do all sorts of crazy things. The fuel flow not set by the jet alone, all systems have an airjet that bleeds air into the fuel to make it lighter and react quicker. If they increase the airjet, they can increase the fuel jet too but it could still flow LESS fuel than before. One of those weird things. On pulling done ANY 5200 I ALWAYS mark all jet positions on a piece of paper for future reference. Some are backwards as compared to others. I'm talking known factory built carbs not torn into by anyone before.
Why you do NOT want to mix up the airjets either.
I remember once pulling apart the 5200 on my Mustang II long ago when car just totally spit its' guts out and stranded me. Pulled a long piece of looked like yarn out of the fuel bowl and wondering 'how on earth that got past the filter?'. Like a 4 inch long piece. Just crazy.
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To OP, if you can give the R-(XXXX) number off the bottom flange of the main body, I may well be able to supply factory Ford fuel and air jet sizes out of the Holley Spec catalog. The Ford carb tag not of any use here. The Holley book should spec every 5200 made by them. Any carb made by them starts with 'R'.
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I'll go look in a sec, that would be great!
On an unrelated side note, this is the first car I've ever had that actually still had the metal id tag on it. Lol.
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R- 6309 - 3 is the number on the baseplate.
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That one shows original application was a '72 Pinto 2.0L ATX
Primary idle fuel jet 55, secondary 50.
Main fuel jet 132 primary, secondary 135.
Note: the catalog is messed up on the idle jet positions. It calls the key number out for primary but is indicating the secondary position in the carb breakdown picture. Vice versa for the other one. The actual numbers I gave you may be right anyway, if they were input into catalog from a simple list instead of that same mis-translation of the call out pic. They WILL be right for values, just may be mixed up as to the position. Five million numbers in a catalog, sooner or later somebody had to fudge up somewhere..... .......
Thinking the primary slightly bigger to have reserve for the curb idle screw, two fuel circuits on the primary side, only one on the secondary. You also want the one with the adjustment screw slightly bigger so that you can go slightly rich with the screw as an indicator you've gone too far, it helps when setting the screw. Of course there are carbs where that reverses so go figure........ ..
From the 'Holley Carburetor Illustrated Parts and Specs Manual' dated 1975, I bought mine around '78 or so.
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You, Kind Sir, have my sincerest thanks. That was spot-on what and where my jets are. Now I know what to shop for in a tuning kit, size-wise.
Kudos. Seriously, kudos.
Edit: Lol. Everybody's human. Mistakes happen. :)
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Would this get me close? The motor is happy now, but wants more fuel and spark advance. :)
http://www.ebay.com/itm/WEBER-Redline-32-36-DFV-DFEV-DFAV-Carburetor-Carb-Jetting-Jet-Pack-Kit-NEW-/281155905196?pt=Motors_Car_Truck_Parts_Accessories&hash=item417632a6ac&vxp=mtr
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Long shot there......... ........been a long time since I went looking for Pinto jets. I'd bet the numbering could be different, and changing to a Weber was a mistake in my day, they had no power valves and absolutely sucked for mileage as a result. Of course now that could be different. The lack of a PV will surely tilt the jet package. No PV means the main must get much bigger.
I know what the conventional wisdom says, but I carefully drilled by hand when I wanted bigger jets back in the day, and had no trouble at all. Had a Holley chart showing the absolute hole sizes of marked jets. A few overlapped by virtue of the finish being different on same hole size but the ones I drilled (using a modeler's pin vise) showed more fuel when used.
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Five minutes of research on the web says I'm wrong. Appears Holley and Weber used same nomenclature for jets. Kit should work but I didn't find the main sizes supplied in it, only three may not help.
Kit a bit high to me, I wouldn't use half of it. Once the air jets are locked in, rare to need to change them. I like separate stuff, of course the shipping can kill you........... .
http://www.racetep.com/weberX.html#jets
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I'm aware of 'Racetep', but they're not on eBay. I figure with a brand new 32/36, my current state of tune, and a tuning kit...we're walking in high cotton.
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Your stuff, your choice as always Daddio........ ...........
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Correct me if I'm wrong. :)
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That one shows original application was a '72 Pinto 2.0L ATX
Primary idle fuel jet 55, secondary 50.
Main fuel jet 132 primary, secondary 135.
Note: the catalog is messed up on the idle jet positions. It calls the key number out for primary but is indicating the secondary position in the carb breakdown picture. Vice versa for the other one. The actual numbers I gave you may be right anyway, if they were input into catalog from a simple list instead of that same mis-translation of the call out pic. They WILL be right for values, just may be mixed up as to the position. Five million numbers in a catalog, sooner or later somebody had to fudge up somewhere..... .......
Thinking the primary slightly bigger to have reserve for the curb idle screw, two fuel circuits on the primary side, only one on the secondary. You also want the one with the adjustment screw slightly bigger so that you can go slightly rich with the screw as an indicator you've gone too far, it helps when setting the screw. I'd be going with the 55 in primary....... .......
From the 'Holley Carburetor Illustrated Parts and Specs Manual' dated 1975, I bought mine around '78 or so.
Would you happen to have the specs for R-6655?, I can't find anything on it, it was on the car and I'm sure it's not what came on there originally. Thanks..
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Two listed there, 6655 and 6655-1, both show Ford Pinto 2.0L MTX and for 49 states not California. Both use pretty much same hard parts.
primary idle fuel jet 60
secondary idle fuel jet 80
primary main fuel 137
secondary main fuel 135
And yes, the number spread seems reversed from the last set given. I triple checked to be sure of what catalog says. I have found this in junkyard carbs before too. The fuel jet depends upon the airjet, you can have a smaller fuel jet and still flow more fuel. The airjet determines the draw on the main fuel jet and same exact main fuel jet can be made to supply more or less fuel.
There are some carbs where the idle fuel jet is blocked off and not installed either front or rear, for reasons of their own the OEM using that carb wanted to make sure it was harder for people to mess with emission settings. There will be an idle jet somewhere as you MUST have one, but pressed down inside a channel so hard to find and mod. Or they may be looking at costs savings of drilling, tapping more holes too. Them guys will throw a party over one hole saved on 50,000 cars, and someone will probably get a bonus for finding the cost saving.
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Excellent information AMC- Really good hard to find stuff!
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Two listed there, 6655 and 6655-1, both show Ford Pinto 2.0L MTX and for 49 states not California. Both use pretty much same hard parts.
primary idle fuel jet 60
secondary idle fuel jet 80
primary main fuel 137
secondary main fuel 135
And yes, the number spread seems reversed from the last set given. I triple checked to be sure of what catalog says. I have found this in junkyard carbs before too. The fuel jet depends upon the airjet, you can have a smaller fuel jet and still flow more fuel. The airjet determines the draw on the main fuel jet and same exact main fuel jet can be made to supply more or less fuel.
There are some carbs where the idle fuel jet is blocked off and not installed either front or rear, for reasons of their own the OEM using that carb wanted to make sure it was harder for people to mess with emission settings. There will be an idle jet somewhere as you MUST have one, but pressed down inside a channel so hard to find and mod. Or they may be looking at costs savings of drilling, tapping more holes too. Them guys will throw a party over one hole saved on 50,000 cars, and someone will probably get a bonus for finding the cost saving.
Thanks much for the info, I looked at the idle jets and can't see any numbers on them, are those numbers hole sizes?, the main jets don't have anything on them either but the hole size was .050 and .055??, and the high speeds have 70P and 90S. I know the idle jets need to be changed since the idle mixture screw is barely a 1/4 turn out and still don't idle quite right.
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Should help.......... ...go down just past halfway to 'Holley 5200 jets' section.
http://www.mazdatrucking.com/B2200/5200.html
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Should help.......... ...go down just past halfway to 'Holley 5200 jets' section.
http://www.mazdatrucking.com/B2200/5200.html
Thanks, I just found that site last night.. Of course the ignition is crap so I probably should fix that before messing with the carb, LOL..
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Thanks, I just found that site last night.. Of course the ignition is crap so I probably should fix that before messing with the carb, LOL..
Definitely do replace your ignition first. That's what led me to my belief that I need slightly more richness. (Which, I had wondered, as Chiltons states that one of the emissions features for 72 is an 'Emissions-rated carb'. Then after my discovery that my random miss was distributor cap related, and general running condition was still yet improved by a fresh set of plugs and wires (both under 7000 miles/12 mos in age) this weekend, it's evidently lacking something.
My list of fresh ignition parts: distributor, points (new), condensor (new), rotor (new), coil, wires (new), plugs (new). All gapped and set according to spec, timing set to 8 degrees, verified no vac leaks, new cam, fresh head rebuild, etc. Also new within 7000 miles: thermostat, coolant system hoses, radiator flushed, battery (new, with fresh connections).
Beyond that, it needs more gas. :) Thoughts welcomed, but carb and tuning parts on the way, anyway. Cause shiney is good!!! :)
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Well, don't have no emissions here so I'm lucky there, distributor is crap so I'm gonna ditch the points and go HEI, may not even have to do anything to carb after that, lol..
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Man I converted my points to electronic long ago, and a mistake not to. The engine just runs so much longer and smoother the whole way. As soon as I found junkyard parts it was done.
Hot ignition clears up a lot of perceived carb troubles. When you put a suddenly hot firing ignition on you can experience a need for slightly more fuel when the hotter spark burns all you have and asks for more. MANY erratic but perceived as incorrect jetting issues can be solved with electronic ignition.
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Yep, points to electronic is like night and day..
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I can tune Weber IDF's with my eyes closed but my 5200 was a 1st time attempt. I know the fuel jets are the ones in the bowl submerged in gas but are the 2 upper jets for air or are they fuel as well?
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Yes they flow fuel for the idle circuit.
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Great, so there's no way to put smaller air correctors in to richen it up? That means drilling my fuel jets
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The ones on the top are the air bleeds.
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The ones on the top are the air bleeds.
Oh OK, so if I install the smaller pair that came with the carb combined with the larger fuel jets I installed from the stock carb it should richen it up. I swapped all 4 assuming they were all fuel related. I forget the sizes but all 4 stock jets were larger than the jets in the NOS carb.
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It is a Weber. Define 'top', Good Sir. The two you can't see without removing the air cleaner are your 'air correctors'. The one you can see without removing your air cleaner is your Primary Idle jet. The one you have to crook your head around your valve cleaner...well ...that's your secondary idle jet, and that doesn't come into play until over 2200 rpm.
The two under your 'air correctors' are your 'emulsion tubes', which everything I have read says should not be touched unless you are an air/fuel ratio meter. :D lol
If it doesn't fit this: Speed screw less than 1 & 1/2 turns from not touching, and mixture between 1 & 1/4 to 1 & 3/4 turns from bottomed, then your Weber isn't jetted correctly.
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Believe me, unless you have STRONG reason to and are a tuning guru, you do not want to change any AIR jet on a carb. Not as simple as fuel changes, and much harder to understand the effect. Changing a fuel jet pretty much richens everywhere, change an airjet or emulsion tube and you change the entire CURVE of fuel, say low fuel at low rpm to high fuel at same rpm but the same fuel amount further up the range. The change is NOT equilateral across the whole spectrum of the jet use at all. Think of a steep ramp as versus a shallower one, but with same fuel at the top, or same fuel at the bottom. Now take that steep ramp and grab it in the middle and yank it one way or the other, what airjets and emulsion tubes can do. You can get lost there so fast it's not funny.
When you have a carb pretty much dialed in like stock ones are you are dollars to donuts miles ahead by changing fuel jets only.
Say I have car that runs too lean at less rpm and too rich at higher, all at WOT so mainjet only, how would you correct it? Think about it. Oh, and I took the power valve away from you too........... .............. .....
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Oh OK, so if I install the smaller pair that came with the carb combined with the larger fuel jets I installed from the stock carb it should richen it up. I swapped all 4 assuming they were all fuel related. I forget the sizes but all 4 stock jets were larger than the jets in the NOS carb.
Probably time to go back to square one and start over, and only "one" change at a time, shouldn't really have to change the air bleeds unless you did extensive mods on the motor?. . Don't know if you seen this before but this explains how the different circuits work, it is pretty simple.
http://www.thesamba.com/vw/archives/manuals/holley_carburetor/Holley_5200_Carburetor.pdf
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So, I remembered why my brain said 'It needs more fuel.' All the gas around here that you can find anymore is E10. Now, as we all (should know), adding ethanol to your gas sounds good (in theory, but not really), but it decreases fuel mileage. Why? Less potential energy. Modern vehicles can compensate for it on the fly, but we have to adjust through tuning. Have you ever read the jetting specs for an alcohol powered drag car? They're HUGE!!!
That's all I wanted to say. Hope everybody's having a great Labor Day weekend!!! :D
Keep it between the ditches. :)
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I'm not too bad at chasing jetting. I swapped all 4 jets because the NOS carb was running lean & all 4 jets were smaller than my stock carb. It's not AS lean now but it's still lean. Putting the smaller air corrector jets that came with the NOS carb back in & leaving the larger 36 year old fuel jets in place should richen the mixture. My plugs are white & ashy.
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Is the idle circuit lean also?, changing the idle jets only affect the idle mixture at idle, you only need to change those if you can't get an adjustment on the mixture screw, once the butterfly is past the transfer slot you're on the main and the idle jets have no effect.
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Is the idle circuit lean also?, changing the idle jets only affect the idle mixture at idle, you only need to change those if you can't get an adjustment on the mixture screw, once the butterfly is past the transfer slot you're on the main and the idle jets have no effect.
My brain is too tired to process the thought it is trying to get out, but in a Weber-designed carb, the progression holes (first ones uncovered if you flip it over and look just above the mixture screw) is also fed by the idle jet. I had a page with an illustration, but forgot to bookmark it. Thus the "speed screw open no more than 1 to 1&1/2 turns, mixture screw no more than 2 turns out" rule. The speed screw too far in is fudging a too lean idle jet by uncovering the progression circuit (and causes a flat spot when you tip in because you are idling on your enrichment circuit).
Does that make sense?
Eta: What you said is spot on for a standard Holley-design carb (your typical Motorcraft/Autolite carb, etc).
Eta 2: Not exactly what I was looking for, but shows the circuit pretty well. Notice how the hole right above the throttle plates are fed from the channel that feeds the idle mixture screw. https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=VFqNCfVDaDhFKM&tbnid=W3T5fTYa4xV2BM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.webercarburatori.com%2F%3Fp%3Dhandbook%26s%3D2&ei=25gnUrORB8rC4AO1kIDYDQ&bvm=bv.51495398,d.dmg&psig=AFQjCNFnNmr0FiMJQYyPBuuIo-XrNUgIWA&ust=1378413057600345
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Yep it makes sense and I know how it works just didn't word it right I guess, but basics are the same though just more adjustability with the Weber which makes them superior over most carbs.