Holley stumble trouble

Fuel and Air Systems

  1. mderoy340

    mderoy340 Well-Known Member

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    Well those appear to have the E tubes in them.
     
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    • SSG_Karg

      SSG_Karg Stuck in the middle

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      MAB - #72 bit (.024”)
      IAB - .053“

      This hole at bottom of main well .031”. (Idle jet)

      EF433759-0045-4537-8860-6B463B335C6C.jpeg
       
      Last edited: Jul 28, 2020
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      • SSG_Karg

        SSG_Karg Stuck in the middle

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        Hole at top of dogleg is .027”

        94B409E6-DA03-44AB-AC33-40235B827188.jpeg
         
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        • yellow rose

          yellow rose Master Of Insanity

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          Are the vertical holes in the e well drilled or blank?
           
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          • SSG_Karg

            SSG_Karg Stuck in the middle

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            These?

            A133EAA8-4CA3-4025-B013-CA94DC975BEF.jpeg
            Drilled .028”
             
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            • yellow rose

              yellow rose Master Of Insanity

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              Yep that’s what I was asking. That seems strange to me.

              I’m going to post a couple of pictures of a metering block I have here that is very strange too.
               
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              • Mattax

                Mattax Just the facts, ma'am FABO Gold Member

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                I'm not a guy with a lot experience in removing the well plugs and e-tubes.
                All I can say is look at some of the things Mike (GNTKLLR) found and discusses in this thread.
                New and improved 1850...?

                One of them is a block where the e-holes were drilled in one air well and not the other. :realcrazy:
                In post #6 he has a 11761 metering block with flat caps but no e-tubes...
                 
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                • mderoy340

                  mderoy340 Well-Known Member

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                  The two orifices that is out of whack to me is the .053 IAB and the .024 MAB.
                  The .024 MAB delays the primary start, a .026 or .028 is what I run with 2 hole emulsion blocks.
                  The .053 IAB is normally .070 or .073 with today's carbs. On a 650 or 750 I run a .033 IFR and .067 or .070 IAB.
                  I believe your issue is a combo of to lean on idle/transition and slightly delayed primary coming in at light throttle. When you continue getting in the throttle the signal increases and primary have full flow.
                  Threaded brass set screws are the way to go if you really want to dial in. 6/32 x 1/8 for IFR, EML, MAB. 8/32 x 1/8 for IAB, PVRC, TSR.
                  Today's pump gas contains ethanol and it takes more fuel to equal the same BTUs real gasoline produces. Old carbs were setup for pure gasoline.
                   
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                  • yellow rose

                    yellow rose Master Of Insanity

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                    I agree with that but did you see the picture of his metering block? It has a weird kill bleed location and some other stuff I forget without looking at the picture again.
                     
                  • mderoy340

                    mderoy340 Well-Known Member

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                    I've run a 600 1850 without E tubes 2x.028 EML with the same kill bleed location with no issues.
                     
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                    • Mattax

                      Mattax Just the facts, ma'am FABO Gold Member

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                      Read the discussion I linked to. Especially the discussion between Deep Roots and Tuner toward the end. This seems to be one of those situations where sometimes the kill bleed in the dogleg is just enough to really kill the start of the boosters and sometimes its not a problem at all.
                      When I get my car running, I'll be curious to see how well my 650 carb does with those dogleg holes now plugged.

                      I agree the IAB in particular seems very small. Maybe that's the secondary block??
                      Deeproots and Gntkllr posted a fair number of combos that should be good guidance for getting this into the ballpark. IIRC numbers are all in the same range as you (Mderoy) suggest.
                      Also in the same range as my 650 VS. I don't have 600 or 650 DP or I'd post that too.
                      upload_2020-7-29_15-40-25.png

                      upload_2020-7-29_15-41-57.png

                      So primary IFR is just over .033" and IAB is .073"
                      I decided to drill regular kill bleeds in both blocks. I'm not sure if the ones in the primary block will help or hurt. On secondary block that was specifically done as a siphon break.
                      The reason I've reduced the primary high speed air bleeds was because the AFR on the dyno was showing increasing need for correction corresponding to the reduction in jet sizes. Only when I take it to the track with a working logger will I know whether this was a move in the right direction, and if it was, whether it was sufficient, too much or too little.
                       
                      Last edited: Jul 29, 2020
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                      • mderoy340

                        mderoy340 Well-Known Member

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                        2x.027 and .026 or .028 MAB has always given me a flat fuel curve with a fuel delivery system that can feed the motor.
                         
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                        • SSG_Karg

                          SSG_Karg Stuck in the middle

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                          ^^^^This is what I’ve suspected the whole time. Question is, how to correct it? I’m not sure I’m interested in trying to drill out these tiny holes or press in new ones. Perhaps a replacement adjustable metering block is in order here. I briefly considered a ProForm main body but they do not come with blocks and there is no provision for a vacuum advance port if using my existing block.
                          Negative. It’s the primary. I’m gonna measure again to be sure but I was pretty careful the first time around.
                           
                        • yellow rose

                          yellow rose Master Of Insanity

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                          Don’t let drilling and tapping a few holes screw you up. You can do it.

                          I have a metering block that’s more whacked than yours, and when it cools off I’ll post a couple of pictures. Waiting to hear from Tuner. I suspect he’s pretty busy, but when he calls me back I’ll fill him in and see what he says.

                          He is a sharp guy.
                           
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                          • mderoy340

                            mderoy340 Well-Known Member

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                            I would drill the Primary MAB to .026, the IAB to .067, and the IFR to .033
                            Here's a good read for modifying and tuning. It's not rocket science, but is time consuming. You will also have a lot of folks looking at your tail lights.
                            Carb Tunning
                             
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                            • Mattax

                              Mattax Just the facts, ma'am FABO Gold Member

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                              Go make a sheet or table like I poisted or there's ones on Racing Fuel System as well.
                              Write everything down.
                              Since the mains started at different rpms, it wouldn't hurt to pin every bleed and restriction. One side could be different than the other.
                              Take out the jets and see if there are tubes. I'm betting not but......

                              My approach is normally the slow approach.
                              I'd do each of these seperately and take it for a drive.
                              * Plug those holes in the primary block's doglegs with fuel resistant epoxy - like for fuel tanks.
                              * Open the IAB's to something normal, but start on the small side - like .070
                              * MAB to .026
                              * IFR to .033, and then open the IAB a hair if needed

                              First one because I think it serves no purpose and is likely to be the root of the evit - assuming no e-tubes.
                              If there's e-tubes, then plug the eholes in the channel with some lead or a set screw.

                              Second because I agree this is an odd combo - maybe due to the holes in the doglegs but it aint doing the trick if that was the intent.

                              Third, if the above isn't doing it, then maybe the MAB is too small. .026 is not unreasonable.
                              Finally, if it really is running out of fuel in the idle circuit, then a larger IFR should keep it flowing to a higher rpm. A larger IAB may be needed to trim it to the same AFR as before.
                               
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                              • yellow rose

                                yellow rose Master Of Insanity

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                                Here is what I’m working on.

                                2A046359-7398-40E1-8AEF-23FC9591EB95.jpeg 0925F86E-6BD4-4E5E-9F35-8F77E4284DC2.jpeg 945C5E20-9F65-4B44-BD21-92BA3200EE0D.jpeg

                                This has an IAB of .082 and it doesn’t even look like it has any idle feed restriction. I pinned it at .080 but that can’t be right. And the upper bleed is .040 and the lower one is .028. Definitely has tube emulsion.
                                 
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                                • Mattax

                                  Mattax Just the facts, ma'am FABO Gold Member

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                                  You think it has IFRs in the idle up wells?
                                  We talked about this - maybe even found a pic - certainly a description - from Tuner.

                                  I'm I seeing holes in the dog legs and a bleed into the angle channel? I sure hope there's e-tubes in that case!
                                   
                                • yellow rose

                                  yellow rose Master Of Insanity

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                                  If the IFR’s are up there, I can’t find them. It looks to have e tubes in them, but I want to run this past Tuner before I change anything.
                                   
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