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 Post Posted: Mon Apr 04, 2011 3:52 pm 
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No, I set the jig up off the existing hole, although it looks like some may be slightly off where they intersect the mainwell and could stand to be corrected unless they have a reason to do so. Something more to look at in the future.


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 Post Posted: Thu Apr 07, 2011 3:06 pm 
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Got those metering blocks today from Holley and they are identical to the ones that are in my 1150 Dominator. They came with jets, power valves, vent whistles and bowl gaskets. Now to make a fixture to hold them so I can machine out the crosswells! ;-)

Anyone know of a cheap source for a small compound vise? :-k

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 Post Posted: Thu Apr 07, 2011 3:40 pm 
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This is what I have.

http://toolsandmore.us/shop-fox-d2933-angle-vise.aspx


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 Post Posted: Thu Apr 07, 2011 5:18 pm 
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Hummm, these metering blocks are somewhat different from the ones in my other Dominator?? There's no idle fuel transfer port on the face where we normally put the IJ?? If you look on the fuel bowl side though there is what appears to be an approximately .078/.093 hole in the bottom of the idle wells that seems to be where idle and transfer slot fuel is distributed. On the other side there are NO holes where the normal IJ and feed from the mainwell are located?? The IJ is in the top, not at the bottom like my other blocks are?

So, these may have the same part number but they're made different.

Came with a .144 MJ with a PV and a .116 PVCR fixed orifice. That's a lot of area for a .203 crosswell though. These blocks were originally put on a 950 HP 4150 carb.

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 Post Posted: Thu Apr 07, 2011 5:31 pm 
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That would make idle fuel independent from the mainwell and main jet, while I have seen it done that way with alcohol I am not sure that is the best way to do it.


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 Post Posted: Thu Apr 07, 2011 7:10 pm 
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jmarkaudio wrote:
That would make idle fuel independent from the mainwell and main jet, while I have seen it done that way with alcohol I am not sure that is the best way to do it.


That completely divorces the idle and T slot fuel from the mainwell. May not be a bad idea since the T slot circuit "can" become an air bleed at some points in the fuel curve. :-k

You had mentioned to me some time back that you had seen or heard of Ken Jones or Dragchevette having plugs in the BOTTOM of the metering block on some carbs? Wonder if that was to plug that idlewell feed and not anything to do with the mainwell? After pulling the plug on that idle circuit the only way I can see to plug it is to go in from the bottom. That idlewell is only .106 dia and the orifice in the bottom is just a tick smaller than that. A 6x32 or 8x32 tap won't reach the bottom where the metering orifice is.

Gonna think about this some and I'm open to ideas of why it might or might not be good way to do this? FYI, the other set of blocks have the "traditional" IJ location pulling off the bottom of the mainwell.

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 Post Posted: Thu Apr 07, 2011 7:19 pm 
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Separating the low load and high load circuits Is not a problem except for the transition point between one circuit and the other.its much easier to achieve a correct fueling strategy across the transition air flow range when there is a main jet controlling the overall flow. For your type of racing there is virtually no disadvantage with separating the circuits. The transition slot tuning becomes more sensitive, thats about it. That said there is also no gain by doing the separation modification. If the correct size barrels and main jet are used with appropriate emulsion and metering block drilling sizes then there is no problem with the transfer slot becoming an air bleed, which is the main reason for doing the separation thing . Its the same old thing, do the physics right and be observant of what you truly need to do and you dont need to be fancy, the KISS principle works very well. .


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 Post Posted: Thu Apr 07, 2011 7:23 pm 
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Ken0069 wrote:

That completely divorces the idle and T slot fuel from the mainwell. May not be a bad idea since the T slot circuit "can" become an air bleed at some points in the fuel curve. :-k


the tslot does that when the IAB is too small. Just make the IAB bigger and it stops doing it.


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 Post Posted: Wed May 25, 2011 10:10 am 
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OK so it's been a while since I've done anything with this and another thought came to mind. The IJ is in the TOP of that channel on these new blocks and there's no way to put it at the bottom because the needle comes through into that cavity. Is this going to be a problem?

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 Post Posted: Wed May 25, 2011 10:33 am 
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Ken, sounds like a similar situation with the metering blocks on this post.

viewtopic.php?f=6&t=8250


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 Post Posted: Wed May 25, 2011 12:37 pm 
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Yeah, that was another thought along these same lines although up the page shrinker didn't think it would be THAT much of an issue. I've recently gotten a 1/16 NPT tap and some brass plugs and I could "try" to change it over if needed. I can drill and tap the bottom of the block over that new idle feed hole then block it with a 6/32 screw. It has the place in the casting for the regular idle feed holes so it shouldn't be that hard to make those work. But then again, if there's on real advantage to doing that then I'm all for leaving them alone. May do that anyway just to see how it does as I can always go back and change it.

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 Post Posted: Wed May 25, 2011 6:27 pm 
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Ken-, if your considering divorcing the idle circuit then you should be aware of this.
If the idle circuit is divorced there is less flow through the main jet so the main jet could be smaller as all it has to do is feed the booster. However at sufficient CFM at full open throttle the restriction of the butterfly shaft starts to generate significant fuel flow from the T-slot. That creates rising richness as the RPM's go up and you cant stop it because the main jet isnt controlling the entire fueling relative to one restriction point, which is the main venturi. For booster emulsion style carbys divorcing the IFR is a bad idea unless you have an exact engine to carby match. Its not an idea for individuals to play around tuning things. The reason for divorcing the IFR is to have 2 independent fuel sources for alcohol where the problem is how to get enough fuel into the engine. Holleys are on the edge for fueling alcohol 650hp in a single carby form. I have not seen an alcohol engine that runs correctly controlled combustion across the entire engine operating range. They work for drag racers because they only operate in a small range but they dont work for other sports except boats.


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 Post Posted: Wed May 25, 2011 10:42 pm 
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shrinker wrote:
Ken-, if your considering divorcing the idle circuit then you should be aware of this.


That's not what I'm talking about doing here shrinker. These NEW Holley blocks I got a few months ago ALREADY HAVE DIVORCED IDLE CIRCUITS IN'EM! My old Holley metering blocks in the other Dominator with same part number had the standard idle circuit that feeds off the mainwell. What I'm considering doing is to make the NEW blocks feed off the mainwells like the OLD blocks do now.

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 Post Posted: Wed May 25, 2011 10:45 pm 
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Thats a good conversion option to do.


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 Post Posted: Fri Jun 24, 2011 5:38 pm 
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OK so I finally got back on my new to me methanol carb main body external linkage deal and pretty much finished that up today. Now I'm beginning to concentrate on the metering blocks to see what I can do there to feed a .234 ID banjo with 12 .078 holes in the booster. Looks like the #3 taper reamer is too small and the #4 is too large. That and the angle over the distance from the jet to the crosswells is going to be too much even if I grind a #4 down to that .230+/- dimension I'm looking to get too where the mainwells intercept the crosswells. Looks like I may have to rethink my maximum jet size in order to be able to use a taper reamer at all.

The mainwell in these metering blocks is about 1.575 from the bottom to the top of the crosswell exit. That #4 reamer is .0215 taper per inch. If I use a .225 jet and make the mainwell just .225 at the bottom then the 1.575 distance up will net me about .030 increase which will make it about .255, much more than the .234 ID of the banjos. It's looking more like my maximum jet size will have to be somewhat lower than my .225 original target to be able to accommodate a tapered mainwell.

So having said all that, what do you guys think about doing step drilling in the mainwell to get to where I need to be at the crosswells, or somewhere close? :-k

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