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Discussion Starter · #61 ·
Because I tried bigger jets and they didn't make any difference! And if you saw, I was told they are probably too large.
And just to be sure, I went to size 92 jets this afternoon with no improvement.

I'm thinking of a way, not to fix it but just as a test, to stick some fine wire into the air bleeds to restrict the flow. I'll solder all the wires together and secure them so they can't get sucked inside. Again this is not a FIX, it's just a TEST.

Even with it running so lean, either I forgot how it ran before, or it's picked up some horses compared to using 40+- year old carbs. It is 50 more cfm.
 

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I never tried peening the air bleeds and redrilling them but if I did I would worry about getting shavings in the well and not being able to get those out. I would think that removing them, drill/tap as needed for regular bleeds would be the better way to go. If you don't want to speed the cash for the drills and taps, you could probably get a local carb shop to do it or contact AED in Richmond.
 

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Discussion Starter · #63 ·
Today I had the chance to try my half &ss way to tell if smaller air bleeds would help, by sticking some fine wire into the air bleeds. It was a success! I didn't get an exact measurement of the factory air bleeds, and of course I forget at the moment what size wire I put in them, but it worked. It didn't go quite as rich as I wanted, but it's the first thing I did that enriched it at WOT. I believe I could drill and pull them just so they aren't pressed in extremely tight, but where would I get new press fit ones? Or do shops tap them and install replaceable bleeds?

Another possibility which the more I think about it the more I'm considering it, is to solder the top of the bleeds closed then drill them out smaller. I'll have to check the numbered metric drill bits I bought and haven't used yet to see if they go as small, and smaller than the current bleeds. That would let me start small and slowly increase the size.
 

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if you are gonna do it, do it right and drill and tap for new bleeds. then start going 1 size at a time smaller. the holley listing guide on holley.com will tell you what size the originals are and then you can go from there.

a bleed set is stupid expensive but buying a few is more affordable. if you can figure the area of the existing bleed and the area of the wire and do the math you should be able to get a few sets in the ball park. you can also go smaller and drill up.
 

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If the bigger jets didn't work by themselves and the temporary air bleed size reduction did, that would indicate to me that someone had opened up the secondary air bleeds a bunch.

It would be a good idea, no matter how you fix the air bleeds, that it would be wise to find out what the stock air bleed size should be for that carb.

Were you running this carb when you were going to the track? In a way I'm surprised that you haven't damaged the engine.

You'll probably need to source a drill index of very small numbered bits (I think they are #61-80) as well as a hand held "pin vise". Don't try to use a power tool on holes that small.
 

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Discussion Starter · #68 · (Edited)
I could barely get the non drill end of a .070mm drill bit in the air bleed, so that's about .025". Do these sound like factory size air bleeds?

RickL, Yes I have a pin vise... somewhere. I'm not a total idiot, I know enough that the pin vise is the way to go. Even with that I'm a bit afraid of breaking a drill bit, but I suppose if I go easy enough it will work.

I've looked high and low for the information from Holley on the size of the original air bleeds. Hotrodg, if you know where this info is I'd appreciate it if you could share that link with me? Again the carb is an 80531. I've found lists that give all kinds of info, but none about the air bleeds. Some lists for some reason just happen to skip over the 80531? And the phone tech support guys don't even know what size air bleeds it should have.

I pulled a Holley book off the shelf last night and believe it or not, it says if the air bleeds are too large, they mention bending a wire like a V and sticking it in the air bleed. I'm not sure what the V has to do with it, unless you bend the top ends out left and right to keep them from getting sucked in?

I've only been running the carb for a month and not much at that. Also I mentioned here that I got no knocks or pings when it goes lean if you missed that part. Probably because I had put on aluminum heads and it turned out the old were smaller CC's than the new ones. So my compression when down almost a full point but on the track it ran the same as the old iron heads. I suppose more air flow made up for the lower compression, anyway it doesn't even knock or ping on 87 octane E-10 anymore.
 

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The "wire trick" you read about in the Holley book is for reducing the size of an idle feed orifice in the metering block. (The air bleeds are in the top of the main body.) The reason for the "V" in the wire is so that the metering block gasket will hold it in place (similar to what you did except that you can actually leave it there if you are careful about assembling it without it falling out).

I looked on the Holley site and could find no listing of air bleed size, except for a handful of Dominator carbs that come from Holley with a screw in adjustable air bleed. In fact I've never seen it anywhere (not to say the listing doesn't exist though).

I think you have something confused on the metric drill bit size. It is more likely 0.7 mm not 0.07 mm which is .028". 0.07 mm would be .003" or slightly smaller than a human hair.
 

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.028" is probably close to, if not a stock air bleed.
 

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Discussion Starter · #71 ·
The "wire trick" you read about in the Holley book is for reducing the size of an idle feed orifice in the metering block. (The air bleeds are in the top of the main body.) The reason for the "V" in the wire is so that the metering block gasket will hold it in place (similar to what you did except that you can actually leave it there if you are careful about assembling it without it falling out).

I looked on the Holley site and could find no listing of air bleed size, except for a handful of Dominator carbs that come from Holley with a screw in adjustable air bleed. In fact I've never seen it anywhere (not to say the listing doesn't exist though).

I think you have something confused on the metric drill bit size. It is more likely 0.7 mm not 0.07 mm which is .028". 0.07 mm would be .003" or slightly smaller than a human hair.
Yes Rick on both accounts. I got my reading mixed up with the wire V and that drill bit was a .7 mm or .028"

I see at Summit they sell a Non-Holley kit to drill, tap, and install different air bleeds. Two different ones depending on what threads you want. And Holley sells quite a selection of screw in air bleeds. Although not many that are much smaller than my stock ones.

Is there anything else you can think of that would cause it to be so lean? I seem to remember that I had the same problem with the old Holley spreadbore. I had tried 99 jets and it was still lean. I don't remember how I fixed it.
 

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Yes Rick on both accounts. I got my reading mixed up with the wire V and that drill bit was a .7 mm or .028"

I see at Summit they sell a Non-Holley kit to drill, tap, and install different air bleeds. Two different ones depending on what threads you want. And Holley sells quite a selection of screw in air bleeds. Although not many that are much smaller than my stock ones.

Is there anything else you can think of that would cause it to be so lean? I seem to remember that I had the same problem with the old Holley spreadbore. I had tried 99 jets and it was still lean. I don't remember how I fixed it.
back in the day I would buy solid bleeds and drill my own. you would be surprised how a really small change can make a huge difference.
 

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With the hole size being so small, even .001" or .002" change in diameter is a huge change in flow area, which is proportional to the diameter squared.

Example, if the original hole was .025" and enlarged to .028", that would be a 25% increase in flow area.
 

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Discussion Starter · #74 ·
I just noticed something else wrong with this carb that could have to do with it starting very rich and a pump on the pedal may flood it.
The secondaries aren't always closing all the way. I never really looked at the linkage but thought they shouldn't open until half throttle? The way it is, it's hanging up part way open. Starting it with a really poor idle, then closing the secondaries it idled great!
Before I get in there and start bending linkage I thought I'd ask how it is supposed to work, and if the primary being closed should pull the secondary closed completely? Because right now it is not!

I noticed this the other night and I put in a much stronger spring in the vacuum canister, it seemed fine operating it by hand. But after it ran and I stopped it again, the secondaries were open a little. I looked on the Holley site but can't see that linkage very good... maybe in the parts breakdown I can see what the linkage is suppose to look like. I'll see if there is a different hole where it could go first.
 

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Discussion Starter · #75 ·
I found a different hole, but it doesn't go there. Looking at one on Ebay, it looks like my linkage is bent. Probably someone trying to get the secondaries to open faster/sooner? My linkage where it bends up to go to the secondaries has a 90° bend. In the picture I looked at it is not bent as far. I'll find some other pics before I go bending things. I'll also remove it and look closely for signs of pliers on it.
 

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Discussion Starter · #76 ·
Replying to myself again, the Holley website gives one part number #20-53, for the secondaries and the Summit site gives a different one #20-65. I'm ordering the one Holley says.

In the mean time I bent the rod and I'll see what it does. Looks a hell of a lot better. At closed throttle the secondaries can open just a very little crack by hand, maybe 1/32nd to 1/64 giving it some throttle doesn't look like it is pulling any fuel out of the venturi. If I close that crack I may not be able to slow the hot idle since the linkage would hold it open.

Oh, I looked at the spark plugs on one side and they look like it was very rich. I'll see if it burns off later today with a 6 mile round trip at almost 4krpm then much slower to my house. Just starting it and running it a little, it already cleaned off most of the ground electrode. (why don't they call that an "anode"?)

I have to search to see if I also have a numbered drill set, and look for the pin pin vise. Should I buy a kit to drill and tap the air bleeds or just use a drill bit and a tap I already have? They charge a lot for what *looks* like that's all it includes, and some blanks.
 

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The secondary linkage on the left side should help close the blades. the spring in the diaphram should keep it closed. Some had a screw on the right side of the sec shaft to set the closed angle. If it's not being held against that stop something is amiss or binding.
 

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In the mean time I bent the rod and I'll see what it does. Looks a hell of a lot better. At closed throttle the secondaries can open just a very little crack by hand, maybe 1/32nd to 1/64 giving it some throttle doesn't look like it is pulling any fuel out of the venturi. If I close that crack I may not be able to slow the hot idle since the linkage would hold it open.
In case you haven't looked, look under the carb base to see if there's one of these secondary stop screws. Those things can really help solve problems sometimes.

 

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Discussion Starter · #79 ·
The secondary linkage on the left side should help close the blades. the spring in the diaphram should keep it closed. Some had a screw on the right side of the sec shaft to set the closed angle. If it's not being held against that stop something is amiss or binding.
I did try a much stronger spring. Wow that sure does slow them down from opening.

I didn't see a screw that you describe, if it's like the one nad shows, I'll have to look for it. I don't think it will make a big difference, but maybe a little. Like I said, now the secondaries are closing almost all the way. Just a tiny crack open like 1/32 to 1/64. It was hit and miss before. Evidently the vacuum spring usually closed them, but once in a while it didn't.

Thanks
 

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My understanding of that adjustment screw on a vacuum carb was simply to keep the throttle plates from getting "stuck" in their respective throttle passages. Of course with it slightly cracked you are pulling a touch of fuel which will help the idle circuit. On a double pumper, it definitely helps to use it as it allows you to tune the primary idle screw much better.
 
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