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Discussion Starter · #1 · (Edited)
hello all.
struggling with a lean condition off idle. WAs going to bump this thread but the page suggested starting a new post because of its age.


i am running the idles screws out ~4 turns and increased the pump nozzle to a 35. and still stumble a little.

Anyway,, looking at the idle air bleed spec's it is supposed to be 70/39 out of the box. I have 78/63, The main bleeds are 31s

I called to QF/Holley. as always, they never answer the phone. Anyone else have this mismatch? I am not a professional tuner so i don't really know what it should have but it seems big/lean
 

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Discussion Starter · #2 ·
Also the main Jets are 66 and not 68 as spec'd

 

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Yeah, idle air bleed sizes are very lean, especially the secondary side.
Matches up with the fact you've got to have the idle mixture screws cranked way out trying to get it rich enough.

The main jet size won't matter for the idle circuit problem.
2 jet sizes smaller is a standard tuning jump for testing, so it's fine for right now until you get to WOT testing .

I would leave the idle fuel restrictions as-is, change the air bleeds to what the spec sheet says they should be, put the pump shooter back to stock #31, and give it another test.
 

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I can tell you right now its a quality control issue as I had bought a few of the quick fuel slayer 600 carburetors last year and I had to buy a set of air bleed blanks and drill them to stock size in order to correct what Holley messed up. The problem is the slayer main bodies are the same main bodies used on the Quick Fuel Hot Rod series carbs and also on there Brawler etc and the main body is originally setup for a four corner idle on the other carbs that are the more expensive ones and with either downleg or straight leg boosters and I am figuring in the process of things at times they are just rushed out the door and there not catching the part where its being made for the Slayer series carb which are setup as a two corner idle when you get it out of the box and in the process its being missed and there putting the wrong secondary side idle air bleeds and at times the wrong main air bleeds.

I had one where it had the squared idle air bleeds of .070 front and back on one of my 600 Brawer carbs that has side hung bowls it is also setup as a two corner idle out of the box and the idle air bleeds had to be changed. I then had a good deal on a Quick fuel slayer 600 which has the center hung bowls and the secondary idle air bleeds were .063 and all four main bleeds were .063. Talk about being way off. If the average person who does not know these functions and areas on a carb and to look things over and not know what to find ends up being in the situation your in. The carbs I got were brand new and not returns. I had to buy a few ten packs of air bleed blanks and drill them to size and put them on the carb. But the good thing is they are screw in bleeds and easily fixed.

I have worked on Holley style carbs for a long time and learned the trade of learning to customize carbs that don't have the screw in bleeds to be able to have that option using drill bits and brass allen cup screws and because of a long and drawn out history of receiving Holley carbs that I had to fix because of quality control issues.

I had also bought a few of the Holley brand 600 main bodies of the vacuum secondary and 650 double pumpers and the pressed in air bleeds were always checked for size and stuff but they did a poor job of putting in the boosters and they could be wiggled with my fingers with no effort and I ended up buying a kit from a carb company that allows me to put in screw in boosters to correct and fix them. I had a 670 street avenger main body I used as well from last year and it was the same thing, loose boosters and I did not want to have to fix another one and sent it back to Holley and they looked at it and said they would just send me a new one.

New one came and same problem. I did not even bother this time and its on my list to fix. Holley still had good stuff don't get me wrong but they are like everybody else, more quantity then quality out the door. Buy some air bleeds of a smaller size say .028 as a starting point and it will be easier to drill since they already have a hole drilled in them versus ones that are solid blanks as it will take longer to drill them out. Usually on the 600 slayer it will have .039 on average like you posted above but they have made slight changes on the calibration over the years since Holley bought Quick Fuel out. Same thing on the jets.
 

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And its been a while but I think the primary idle feed restrictor in the metering block should be around .033 but might be .031 as I have seen it vary and the secondary metering plate is unable to be changed and it has been in the past .039 just for reference. Depending on what your engine specs is and camshaft specs etc you might have to lean it out some if its not very radical or if it is a bigger cam say in the [email protected] or over it might be pretty close or might need more. Just make sure before you ever venture into that area of tuning that you educate yourself on what and how they function and I recommend the book below as it will give you all the ins and outs on tuning a Holley style carburetor and helping you with a lot of advanced knowledge on tuning and changing things that the average tuner never seems to learn.


For me on the Quick fuel slayer carb I always remove the metering plate and get a cheap 600 Holley vacuum secondary metering block so like that I can modify it for changeable secondary idle feed restroctors using brass allen cup screws so I can tune it and most of the time lean it out on the idle circuit since my engine does not need such a rich setting on the secondary side and 4150 which means a secondary metering block is on the Holley carb, has more options for fuel rail hookups versus a 4160.

The secondary metering plate can be drilled and tapped for using 6-32 brass allen cup screws as before Holley bought out Quick fuel they used to have that option on them but as always Holley cheapened them out as much as possible and took that feature out. The problem is the angle on doing it. Much easier with a metering block. Not saying you have to run out and get a secondary metering block as if you buy a billet set then its already made for that. I just go to a site called allcarbs.com and they have a secondary metering block conversion kit that has the same metering block used on Holley 670 street avengers and also 650 vacuum secondary Holley brand carbs. Its like $43 for the block and way cheaper then going billet.

Anytime I get a carb regardless if its used or new I always tear it down and measure everything and even check for any warped spots as well. Long story there.

 

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Discussion Starter · #8 ·
Summit has shipped the correct bleeds but they have to come from TX so it will be next week before i see them.

I should just send it all back and wait for an 650 AED to arrive. I only went 4160 for simplicity of install and this motor does not need a DP.

I would go EFI but knowing my success rate with aftermarket parts I will be the guy how gets a dud and spend months screwing with only to toss it out.

Chris
 

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When it comes to duds I am a king when it comes to receiving bad parts. I have had so much bad luck over the last 13 years in general since I learned more about stuff and got into things really hard to fill my brain and carb stuff has been an ongoing thing with me. I have bought some extras and sold some others that I have been through and all I can say is back in late 98 I had a bad run with Holley and went to an Edelbrock carb for about ten years until I decided to go Holley again and learned over time you just receive bad parts here and there.

The thing is beyond Holley and ever since in my understanding since I started to see signs of things at around the year 2000 it seems the days of decent quality control was replaced with quantity first then quality later and has only gotten worse especially since a lot of stuff has went to China and a lot of ups and downs with many aftermarket stuff and many brands that were once separate are now all bought out and owned by one company and the days of many different brands to choose from are pretty much becoming extinct like the dinosaur.

I would not give up on your quick fuel carb as compared to the Holley brand ones they are still better quality and offer more tuning features if they still have them available in the metering blocks besides the air bleeds being changeable. I myself will stick with carb as long as I can get parts for them versus EFI.

I like the simplicity of tuning a carb vs EFI and having to setup all that stuff which I don't doubt I can do its just a hassle for replacing the entire fuel system and if something goes bad on the unit itself then your toast until you can get Holley to fix it and if out of warranty period then your not going to be able to go to a local store and get what you need for a simple fix. That is why I won't convert yet. With the way the world is changing and wanting to go electric, ten years from now we might have nothing for hot rods not even aftermarket parts being available as they seem to want to kill all of it.
 

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Discussion Starter · #10 ·
When it comes to duds I am a king when it comes to receiving bad parts. I have had so much bad luck over the last 13 years in general since I learned more about stuff and got into things really hard to fill my brain and carb stuff has been an ongoing thing with me. I have bought some extras and sold some others that I have been through and all I can say is back in late 98 I had a bad run with Holley and went to an Edelbrock carb for about ten years until I decided to go Holley again and learned over time you just receive bad parts here and there.

The thing is beyond Holley and ever since in my understanding since I started to see signs of things at around the year 2000 it seems the days of decent quality control was replaced with quantity first then quality later and has only gotten worse especially since a lot of stuff has went to China and a lot of ups and downs with many aftermarket stuff and many brands that were once separate are now all bought out and owned by one company and the days of many different brands to choose from are pretty much becoming extinct like the dinosaur.

I would not give up on your quick fuel carb as compared to the Holley brand ones they are still better quality and offer more tuning features if they still have them available in the metering blocks besides the air bleeds being changeable. I myself will stick with carb as long as I can get parts for them versus EFI.

I like the simplicity of tuning a carb vs EFI and having to setup all that stuff which I don't doubt I can do its just a hassle for replacing the entire fuel system and if something goes bad on the unit itself then your toast until you can get Holley to fix it and if out of warranty period then your not going to be able to go to a local store and get what you need for a simple fix. That is why I won't convert yet. With the way the world is changing and wanting to go electric, ten years from now we might have nothing for hot rods not even aftermarket parts being available as they seem to want to kill all of it.
Agree, I want to go EFI on my CJ7 but if I am 500 miles from home, In Moab, Rubicon etc the last person i want to depend on is holley tech support. At least with GM TBI there is a Napa auto parts or a easy donor at the junk yard.
 
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