No I haven’t yet done this yet! I am reading about that now in Dave Emanuel’s book now. Looks like that is a better thing to try before I do any drilling on the plate butterfly.
This passage answered one of my basic questions.
Idle Transfer Slot on secondaries?
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This passage answered one of my basic questions.
There's NO way I will ever drill holes in butterflies. There's always a way around that.
Man if I didn’t know better it looks as if this has been touched….secondary plate adjust right?
Ok Ive adjusted it about 0.030 more open. I will try that on tomorrow and see if it improves things! It’s just before the transfer slop.
mopowers
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I always take those out and put a longer one in from the top. Makes it quicker and easier to adjust.
Thats a great idea! God I love this “place”!
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The reason the idle screws no longer work is you're out of range of their operation and into the T slot. The T slot and idle are fed from the same source so as one increases the other diminishes.
The reason I wasn’t positive if that was the case is because the exposed slot was about 0.050” making an approximate square slit visible as seen by the picture I posted previously. From what I understood this was perfectly acceptable BUT I am not running a stock engine. So maybe other rules of thumb just don’t apply. In any event the cold plugs and lack of air is a problem and opening up the secondaries 0.030” makes sense to me. I just wasn’t sure what the secondary transition slot was doing as I did read somewhere that they too should be slightly revealed. BUT this has been challenged by people here with way more experience that I respect.
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Run a cranking compression test. Just remember the idle circuit sees vacuum when the blades are closed. Once you open the throttle blades the vacuum generated falls away and the transfer slot begins to see more vacuum generated there.
Compression test cold cranking generates approximately 200PSI across all cylinders. It’s high I know but it is what it is. Also oil pressure is about 60PSI at start up dropping to about 50PSI hot soaked.
Are you saying opening up the secondaries.030” will drip my vacuum? Makes sense any idea how much? I’ll measure when I fire it up tomorrow.
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Carbs are a case of suck it and see.
It may be easier to just get an after market main body with adjustable air bleeds to play around with. The pain in the arse with Holleys is changing IFRs at least with adjustable IABs you get a better understanding of what your engine wants.
If you open the throttle valve too much it will make the idle screws unresponsive.
Well sitting on my bench is this…… I however would like to try and get the Holley 650 working as a challenge and learning tool. But those adjustable air bleeds are definitely looking at me straight up!Carbs are a case of suck it and see.
It may easier to just get an after market main body with adjustable air bleeds to play around with. The pain in the arse with Holleys is changing IFRs at least with adjustable IABs you get a better understanding of what your engine wants.
If you open the throttle valve too much it will make the idle screws unresponsive.
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That should be a good start. Change the base plate to the Holley and relocate the IFR to the lower part of the metering block so its submerged. Does the main body have a Tslot restrictor in the body?
Not a bad idea at all to make a hybrid out of both carbs. I’ll certainly would need a lot of hand holding going that route. I would like to continue to try and get this 650 to work first as is and learn as much as I can in the process even if it means yanking it off and on a bunch of times. This I feel is a great learning opportunity and something I have been wanting to do.
Later if I succeed and want to put the 750 in or cobble it together making a hybrid then Ill need your help with that for sure. But I am just starting and don’t want to over complicate or throw in the towel with this carb…..yet…..but great option to think about!
Do this to both carbs regardless of which one you wish to use. This will calm down your idle circuit and make tuning exponentially easier.
racingfuelsystems-Relocating the Holley Idle Jet
In the original Holley carbs the idle feed was located at the bottom and for good reason. NACA paper 49 states in one of the conclusions: "Submerged m
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My guess it doesn’t have have one, my Quickfuel didn’t, drilled and taped the body and made my own with brass set screws.
I didn’t understand your question until I looked at the carb. The transfer slots are only in the base not the body. Thats what you are asking right?
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I was commenting on the Tslot restrictors, they would be jets in the main body of the carb.
So I need to remove the float bowl assy to see the Tslot restrictors?
Yes, that and the metering block. There is a picture of what I’m talking about in the link and an explanation.
Welcome to the rabbit hole of carb tuning!
Ah they are in the metering block. Those look like brass press in “restricters”. Your talking about relocating these?
This is what the Metering block looks like..
No, they are in the main body of the carb, you need to remove the metering block to see them.
In the picture they drilled the hole, tapped it and then drilled set screws to the the size they wanted. Same thing I did.
The top picture is the carb body, the bottom picture is the metering block.
BTW, you don’t have adjustable Tslot.
I don’t see any restrictors in the main body do you?
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