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Discussion Starter · #1 ·
Hello guys this is a first time of me finding this with my Holley carburetor and out of all my years of tuning and troubleshooting my Holley carbs I have never seen anything like this before. I found this a few weeks back while I had my air cleaner off and was checking some things over and found it again today.

What I found was that the rear passenger side main air bleed was full with fuel. I had to take a second take as my shop light was all I can get a good light with but I took a shop towel and tried to dab it and sure enough I could see a wet spot and it was fuel. I rebuilt the carb back in March and it was as clean as can be and I used carb cleaner and my air compressor and it did fine. I have correct fuel pressure at 5.5 psi with my regulator.

I have looked all over my main body back then and it showed no signs of fuel spillage anywhere and everything was as dry as can be. I sprayed the air bleed out with carb cleaner and then blew a quick shot of air into it and it was all dry naturally. I did not have any issues with the carb running bad or any driving problems. Well today I had my air cleaner off again looking over things and checking stuff like I normally do on a regular basis and once again I had fuel that was full to the top of my passenger side main air bleed.

To verify I took a toothpick and I stuck it in and used a big magnifying glass and sure enough the toothpick soaked up the fuel and I could see it on my finger. I looked with my light down in the air bleed and there no sign of anything being plugged up. I even recently had my truck out on a few wide open throttle runs and there was no issues with anything on how it ran. I looked at my air vent and there was no signs of any fuel spilling out.

The metering blocks I used on a previous carb and they worked fine and had no issues with them either. I sold that carb (long story) but kept the blocks as they were only a year old and I have them customized for screw in idle feed restrictors. I then today took an air can and sprayed air into the main air bleed and fuel came out my booster just fine for the quick second I shot it with the air. When my truck is running and I take it out and drive and take the air cleaner off everything is dry and no signs of fuel in the main air bleed.

The only time I see this is after it has been sitting and I do not have any fuel boiling issues or anything like that. I am stumped on this one and do not know what could be causing this weird problem. Runs fine, looks fine and the pressure if fine and truck runs just fine in all driving conditions. My carb is a Holley 1850 600 vacuum secondary if that matters.

Anyone ever see something weird like this before? No other air bleeds had any fuel in them.
 

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Discussion Starter · #3 ·
36 sedan I will check out my booster and see if there is anything in it to restrict it. I never knew that if the booster passages were clogged up that it could cause fuel to be pulled up through the air bleeds. That makes sense to me. I blew out the air bleed and the booster sprayed fuel out very easily and I will keep track on it. If I see it again then I guess at that point I will have to take it apart and blow out the metering block passages and also the check the booster from behind on the main body and see if all is clean. First time for me but makes it odd that only the one bleed would be like that and all the others are fine.

My air cleaner is a K&N style so I need to clean it out and re apply the fluid to it and rule that out but I doubt it is that is it does not look real dirty at all.
 

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Discussion Starter · #4 ·
Well guys here is an update on my situation. I have replaced the intake manifold from the air gap to the Edelbrock performer rpm intake and I am still having the same problem as I can turn my idle mixture screws pretty much all the way in and engine will still run and I can even back the primary idle screw off quite a bit and drop down the idle and I know for fact I am in the right amount of transfer spot exposure as I have always wrote down what amount of turns I can go.

I don't have an o2 gauge to see the air fuel ratio on this thing but I know for a fact the air fuel ratio is jumping all over the place by throttle position and there is no stability on idle and off idle depending on your throttle position when not in park. Moving the throttle regardless at lower highway speeds at 55 mph it will have a studder only in a certain throttle position range but as long as I keep it steady on highway speed at 2300 or more rpm and being at 55 it runs just fine without issue but let off the throttle just a hair then it becomes shaky and studders.

Seems to have a big spike in super lean to super rich in certain areas as I can tell by the way it acts. Never had this before with any build regardless of camshaft specs or intake used. Still doing all of what I spoken before. Its funny in the colder weather of 25 degrees and my engine was running near 200 degrees and it does slightly better then when it is warmer out when its 40 plus degrees or warmer so go figure. I had this thing good and hot and running and out for a good drive.

The one improvement is though I have 17 inches of vacuum again as to where with the air gap intake I only got 16 at best and it was hard to get there. The engine responds better with this intake as well versus the air gap so I have gotten some improvement in that area to a degree.

This is one of the most weird issues I have ever had. I am going to try one more thing on my carb and see how it does and if that does not work then I am out of ideas except to check with a degree wheel at a later date and see if something is up with the camshaft grind and wonder isf something is off with it. I wish I could check the degree without having to take the timing cover off as for the first time in ten years I have a leak free timing cover at the U channel area of the oil pan and would hate to mess with it.

Going to try a few last tricks on my carb and if that does not work then on to more advance checking and will have to see if something is off cam wise. I don't know what else to check as my whole build was checked like a fine tooth comb before it was built and all specs was checked. Have exhausted all else.
 

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I wish I could check the degree without having to take the timing cover off as for the first time in ten years I have a leak free timing cover at the U channel area of the oil pan and would hate to mess with it.
You don't need to remove the timing cover to degree the cam.....you would only need to remove it if you want to change the cam timing.
To just degree the cam and see where it is relative to the crankshaft/piston all you need is accurate TDC and the valvecover off the driver side, pull the rockers off #1 cylinder, and then use the pushrod tip as the indicator test point.

Probably have to pull the waterpump for degree wheel clearance along with working room, but the harmonic balancer and timing cover don't need to come off unless you need to move the cam timing.

If you've got time for a little ignition test, rewire the distributor cap 180° different, then pull distributor and restab it in with the rotor 180° different too.
This will let you see if something in the distributor is making the problem....shaft wobble, mag pick-up flunctuation, etc.
The rich vs lean plug readings should flip-flop location in the motor if the problem comes from the ignition.
 

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Discussion Starter · #6 ·
Ericnova72 I will jot those down as things to do if a few other things I try does not make any changes. I will have to get some custom spark plug wires of a cut to fit variety as the ones I got now would not hookup being 180 degrees out since they are made to length wires. I have a few more things going to try and see but I have to wait till next week once the weather breaks some.

I am going to have to get an ignition box to hookup as well as I like running one as it for me works a lot better then a control module and helps with better spark. I just have not had funds and time to get one hooked up but plan that on my list. Thanks for that idea as I would have not thought of that. I will have to get a degree wheel as well.
 

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Discussion Starter · #8 ·
No the seals are not bad and I have used a total of four different carbs on this build and a previous build and all of them were in working order and no problems with my carbs.As far as my idle feed restrictors goes they are currently .028 primary and .031 secondary which is stock out of the box settings for a Holley 600 vacuum secondary carb. I have worked with these for over ten plus years on many different builds and ran from mild to wild and this particular engine and camshaft I had custom ground is giving me fits like I have never had before and no changes to my carb is changing things on how it acts.

I am going to try a few more things on my carb adjustment wise and see how it does as going leaner should not be needed with my current calibration as it worked on a bone stock 305 in the past and ran excellent and my engine is far from a stock build. I keep notes of all of my previous builds and what my carb settings and calibrations were set at and I should be right in the ball park but unfortunately its not working like it normally should. Something is just off with this something and it had bee like this on two builds with this camshaft.

I have checked everything Boot77 and its just a nightmare and if you read this whole post you will see what I mean.
 

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Discussion Starter · #10 ·
Yes it fires up and runs normal just fine without any issues. Has good throttle response while hitting the throttle in park and in gear. Its just all the other problems its doing that I can't get to change at all regardless of adjustment to my carb or any carb I stick on this engine. It studders while in park and smooths out once in gear and the engine is under load.
 

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Discussion Starter · #11 ·
Here is just a minor update if anyone is curious. I took my carb off and wanted to check it over and I last had my truck running Friday and was trying to adjust the thing to see if I could get any range of the idle mixture screws and hardly got anything at all. I knew my transfer slot had to be good so I decided to take it off today and I took the carb off and my intake was full of fuel residue because of it running so rich and it was still wet I could wipe it up with my fingers and they were dripping.

I know my fuel pressure is good at 5.5 as I checked with my gauge and my regulator is working as it should. I rebuilt this carb last fall and have had no signs of the needle and seats having any problems and float levels are good and never any sings of fuel dripping from the boosters or flooding. As I can run it but its just super fat rich. Took it off and the transfer slots were only about .020 or a hair less so they were square and the secondary side was only open up a 1/4 of a turn.

I took the carb apart to see if anything looked out o the ordinary again like I did with the previous one I used on this thing and all looked good but I can't say for a hundred percent sure but when I tried to slowly as I could take the front fuel bowl off and then the front metering block I wanted to be as careful as possible and see if the power valve chamber area had fuel in it as if I have red correctly in my books or on another forum years ago if you should never have any fuel residue in the chamber if your power valve is sealing good and not blown.

I can't say for sure but I was able to wipe some from inside the chamber with my finger. I took the power valve off and the gasket looked good and is a non stick type and it was good and tight and the power valve was still good as I have a power valve tester and it still held vacuum. I checked the main body with a straight edge and it checked out good as it had the same specs of clearance with a brand new main body I have at the side but it needs to have new boosters installed as the one Holley put in are loose as a goose thanks to poor quality control.

The fuel that I found in the chamber recessed ares of the main body that has the vacuum signal hole for the power valve could have gotten the fuel in it when I took it apart from the gasket but I don't know for sure. The front fuel bowl had less fuel then the rear fuel bowl when I dumped it out and normally the fuel bowls should be about equal give or take a hair even though the front fuel bowl receives the fuel hookup first and fuel can backtrack in the line but I highly doubt it.

I checked the previous carb and the front fuel bowl was still full even after sitting a few months and this one had no difference in using a feeler gauge to see the difference between the outer area of the main body towards the inner power valve recessed area.

The carb is nearly new and about only a few years old when I got it used. So to be on the safe side and to rule out any warpage issues, I used a magic marker and colored it and used a file to file it down as flat as possible and then used a sanding block and spent time to get it as good as possible. I got it down to less then .03 with using a feeler gauge and it would have a faint drag. I don't think this is the issue as the last carb I used the main body was good enough on the flatness according to my rebuild books and what they state what is an acceptable range and I used it before and never a problem.

I only one time had a warpage issue and it was on a brand new 650 double pumper and front fuel bowl would drain during the summer months and be almost empty after three days but I did not have any issues with it running or being able to adjust the mixture screws like this one and previous three other carbs.

The only thing I did find different was that the base plate I am using which is like a brand new base plate, I wondered about the transfer slot length and I took and older 600 vacuum secondary Holley out and looked to see how many turns it took to get .020 on the transfer slot and it took about a 3/4 of a turn to one full turn to get a good square transfer slot range and be square. On this carb it takes at least a minimum of 1 1/2 of a turn to start showing the transfer slot. I took a dial caliper and measured the distance from the bottom of the base plate on the older Holley and it is .365 from the bottom of the base plate and it measured the same on another base plate I got.

On this carb that is on my truck and the same base plate used with the previous two other main bodies that was used with the metering blocks and fuel bowls and other parts, it measures a whopping .020 higher at .385 from the bottom of the base plate. So that is why it takes more turns to get it to show square on the transfer slot and even though the transfer slot is square I wonder if with the throttle having to be open up that far and the transfer slot sitting up .020 higher on this particular base plate is causing it to be open up so far that even though the transfer slot is hardly showing at only .020 with the increase opening that the amount of air coming through is actually pulling a lot more fuel in comparison on what it would pull on another base plate with the transfer slot being less opening needed to get the correct setting of the transfer slot.

I am going to get my truck running either today or tomorrow and see if my sanding on the main body may have found a possible cross channel leak that would not show up in other ways and wonder if perhaps the idle mixture screw ports between the metering block and the main body was perhaps getting just enough of a sealing issue that the power valve chamber vacuum signal could have been sucking constant fuel from the idle mixture channel in the metering block and that was what might be the probem but like I said I had two other main bodies used with this base plate and there were no signs of warpage issues and have used different metering blocks that were brand new and they showed up fine with no warpage signs.

I don't know if that could have maybe been an issue here but the old 377 I had and used a different totally different Holley 600 on it with all different parts front to back and a different base plate altogether I could still adjust the idle mixture screws but over a longer time would still end up fouling out the plugs. Its just on this build being less cubic inch it just happens so much quicker.

Uugh this issue is killing me and intake swap at least the non air gap is better then the air gap design and it has at least given a slight jump in vacuum of about one point even with this big issue and seems to be a better use and the start up is better by some.
 

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Discussion Starter · #12 ·
Ok guys I have a new update and found out some new things that I did not get before. On all previous carbs I had the secondary side opened up at just a 1/4 of a turn and adjusted the primary side to have the transfer slot square and always stayed enough in the proper range that was acceptable. I put my carb back on today and started it up in 45 degree weather and in the past I always needed a choke to get it to warm up till I could adjust things.

Well with the over rich condition I only had to restart it a few times and then I could keep the rpms up and it would warm up and this time it seemed since the intake swap it did not run so stinking bad that it sounded like I had a comp thumper cam in the thing. After I got it warmed up I hooked up my vacuum gauge to keep an eye on things as tring to readjust things. This time I wrote down and reset my transfer slot and this time I had it to where I would not go past .020 on the primary idle regardless of how it ran. At that setting starting off and with my secondary opening at only 1/4 of a turn my idle was only 600 rpm. Before trying anything I tried adjusting my idle mixture to see if I could kill the motor and still I could turn the mixture screws in all the way and the motor would shake a bit but still run.

I then decided to open up the secondary more air into the situation and it picked up my idle to over a bit more. I added another 1/4 of a turn to make it half open. I then was able to take my primary idle and let it down more to where it was at only 1 1/2 turns open on the primary idle setting. Was holding 17 inches of steady vacuum on the gauge. My idle mixture screws going out only made it drop quite a bit. I then proceeded to turn the idle mixture screws in to see if I could kill the motor and put the driver side in all the way and motor would have a tiny shake but nothing to even remotely kill the engine. I even took the primary idle all the way off and it still would not quit but the vacuum naturally dropped from 17 down to 11 but it would still run but sluggishly though.

Reset my idle to 1 1/2 again and then proceed to adjust my mixture screws some more.

Went to the passenger side and turned it in nearly all the way until an 1/8 of a turn and it still would idle but not kill but got shaky. First time I got this to happen. I then decided to open up my secondary side another 1/8 of a turn and this picked my idle up a little bit more and then I turned my primary idle screw down to where its just one turn open and at that point the transfer slot will not show until you go at 1 1/4 turn open on the primary screw.

I then started to work on my idle mixture screws and I turned the driver side in and the engine still would not kill then wen to the other side and then turned the mixture screw and then bam, I got the engine to kill and this was the first time I got it to do this. I then put mixture screws out only an 1/4 of a turn each side and it would still studder while in park and be kind of rough but once dropped in gear it would smooth out a tiny bit but seemed to not run quite smooth.

I gave them another turn to half out and then it would be smooth in gear but still studder in park. I took it to the car wash to get it washed and this is the best it has ran with these settings and ran a heck of a lot better I would say about a 25 percent improvement and there was not hardly any studdering while cruising but still have the studder when I let off the gas and the throttle plate closes.

In all my life I have never had a 600 vacuum secondary Holley carburetor be so pig rich like this on a mild performance build and especially as it shares the same idle calibration as a stock 2 corner idle Holley street avenger 670 as I have the exact same blocks as they use because Holley uses them on both there 600 vacuum secondary if you get there metering block secondary upgrade kit and on the 600 its speced the same exact as the 670 and always in the past it was always to lean on this calibration on the idle circuit.

This carb has 078 primary air bleeds and .048 secondary and the stock .028 primary idle feed restrictor and the stock size .031 idle feed restrictor in the secondary metering block. The 670 has all the same exact specs.

In my past I have used the stock out of box 600 or 670 vacuum secondary carbs and used them on a 350 with a set of 200cc heads that were cast iron but forget what brand and a lunati voodoo hydraulic roller 262/270 211/[email protected] with a 106/112 lobe separation angle with 42 degrees overlap and it would allow me a wide range of adjustment on the mixture screws to be about a 1 to 1 and a half turn out at the most and run excellent and smooth all the way around.

I even stuck a 600 Holley vacumm secondary stock minus the secondary metering block but with the metering plate which still has a .031 idle feed restrictor size to be with the .028 on the primary metering block on an old bone stock late 80's 305 and it ran fine with proper adjustment of the idle mixture screws which I know should work just fine on my build and not be this fat rich.

I know if it was to lean that it would cause me to have to open up my primary side way to much which would cause my transfer slot to be exposed too much and my idle mixture screws would most likely have to be way out to just keep the thing running and would easily kill the engine. But this is the total opposite of all of what it would be like when turning a carb that was to lean.

I know there is no fuel leaks anywhere as the body was redone and I got that ruled out. Never ran severely bad in town but I just know its still to fat cause I can't get practically no adjustment out of the screws except about less then a half a turn which I know means to rich. In the past when I had a quick fuel 600 slayer that out of box was too rich I could only get the idle mixture screws only half way out but if I took the idle all the way off it would still kill the engine.

Only option is to one put in a smaller .028 idle feed restrictor in the rear metering block which I have never had to do before with anything less then a .031 on a build like this or even a stock small block with a bone stock cam to get to to see if it leans it out enough to get adjustment from the idle mixture screws and have proper rage of my transfer slot exposure in relation to everything else. While in gear if you snap the throttle it is very healthy now compared to before but the idle part is still just not right. I have never had to lean a mild Holley 600 like this before.

The only difference in this current cam is its a 268/272 220/[email protected] 510/510 lift but has a wider 110/114 lobe separation angle while in the past most of my cams have been the 106/112 variety and even with the mild voodoo hydraulic roller shaft I posted above the 600 stock holley settings worked well and adjusted well and was spot on for what that engine liked and it had either an Edelbrock PRM or a Weiand Speed warrior intake on it. Same compression for both builds.

Even ran the 600 Holley with just a slight change to a .031/.031 idle feed restrictor combo on that previous 350 from years ago and upgraded to a slight bigger lunati voodoo 219/[email protected] 515/530 lift with a 106/112 and it ran fine with no problems and even with a 670 street avenger with cast blocks or Quick fuel billet blocks with .031/031 idle fed restrictor front and rear with a 2 corner idle setup. So if anyone would like to comment what do you think and what comes across your mind?

The intake swap has helped in some ways while I was cruising through town today compared to the air gap intake and with my needle in a haystack adjustment I found on my carb. It fires up a lot more smoothly compared to before this is with the open spacer and I know if go to a four hole spacer it will only make it super richer as it increases the signal too the carb. In the previous motors I mentioned I used a four hole spacer.

Have to use it to clear the vacuum fitting on the rear for my brake booster as the Edelbrock intakes always have the problem of the fitting not clearing the rear fuel bowl especially a double pumper and I have always gotten good results with spacers in every single build I have done. Hope somebody can come back and maybe have some ideas here.

I don't know if its because of the base plate having the transfer slot machined .020 up higher compared to all my other Holley 600 carbs that I have on hand that needs parts and cleaning etc as they mostly spare parts and such. I don't know if that is causing some sort of effect on the fuel flow coming out of the vacuum discharge ports and while cruising with the transfer slot not being longer like the others is causing some but not all of my problems? This is the same base plate I used on the previous two other 600 carbs.

This is all I can find that could be the problems as going through this like a fine tooth comb. Thanks guys and hope to hear some feedback.
 

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Discussion Starter · #13 ·
Ok buys after the last dang year of pulling my hair and wondering why this thing has not ran from the previous engine to this engine and things not running right and fouling out plugs the mystery has been solved FINALLY! I kept wondering why the previous Holley 600 vacuum secondary carbs worked just fine on my older builds from ten years back and kept thinking what is the difference between the the carbs I used then and this one that I tried on two different engines and kept just doing funky things that was just not normal when it should have not been doing what it was.

I got to checking things and putting my thinking cap on and I know about how critical that transfer slot is and put all my cards on the table and began to rule out this and that and the process of elimination. The older style base plate was the culprit the whole dang time and my hunch about the transfer slot being so far up on the older base plate style versus the newer design that Holley replaced it with over perhaps about ten plus years ago relocating the pcv or brake booster port what ever you want to use it for from the side to the rear and then they made the transfer slot longer in the front side and the secondary side they shortened the transfer slot and I measured all of that.

The older base plate I used on the previous three carb configurations was not warped at all and I used a straight edge on it and at all angles and I got a drag on a .001 size feeler gauge so not a warpage issue at all. I stuck my newer 600 Holley vacuum secondary on and calibrated it like the last carb with the stock out of box settings. .074/.044 idle air bleeds and .025 main bleeds and .028/.031 idle feed restrictors. Opened up the primary side to .015 transfer slot exposure and a half of a turn open up on the secondary and I fired up my engine and let it warm up and I got a little nervous at first but after it got warmer things stabilized out and the vacuum gauge was nice and steady at 16 inches.

Set a 800 rpm idle and the engine was smooth in park and not studdering like before and the idle sounded clean and smooth and the throttle was nice and clean and snappy and I had adjustable idle mixture screws like I should have.

I set them out at 1 1/4 of a turn and with my idle set I started to turn the one idle mixture screw in and after about less then one turn I could feel the engine struggle and knew it was working right and then once I got it to half a turn the engine hardly ran and after turning it in to 1/8 of a turn it quit while touching nothing else.Bam I figured it out.

This is one of those weird things that can't be totally explained why the other base plate would not work correctly but with such a shorter transfer slot that would cause a lot of issues on idle and tip in and off idle. I don't know how it caused all the issues but it was the problem part the whole time. I measured two older base plates like it and they are the same shorter transfer slots up the front about near .400 from the bottom and the newer ones are only about .360 from the bottom. O well its good to go and will be doing the final tuning next week if the weather breaks and I can get some warmer temperatures.

Thanks to everyone who tried to help me out and for all your suggestions and its much appreciated. This case is closed. Finally
 
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