Holley 750 Dominator Booster Change Over

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Walter R. Malik
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Re: Holley 750 Dominator Booster Change Over

Post by Walter R. Malik »

1980RS wrote: Sat Aug 01, 2020 11:56 pm The 1050 8896-2 test did not work out today. I think it's just too fat and my new parts for the 750 conversion don't show up until Monday. I think using a good 2 circuit with the right parts in it will be better than this 8896. Taking out the intermediate bleeds did help a lot though.
The very ORIGINAL L-8896 was vastly different from those future models with this same number having "dash" numbers.
The original had NO intermediate bleeds at all and the idle & high speed bleeds were "pressed-in".
The intermediate discharge was restricted to .046" and that carb had the older "bar" type boosters.

The bar type booster has an entirely different signal curve.
It is actually stronger at high air-flows but, is not very strong at "pullover" so, the minute amount of fuel delivered by that intermediate circuit was used to fill that hole in the fuel delivery curve.
When the annular booster entered the picture, things about fuel delivery changed immensely but, that carb never really got sorted out correctly.
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Re: Holley 750 Dominator Booster Change Over

Post by levisnteeshirt »

jmarkaudio wrote: Tue Jul 28, 2020 10:34 am If you want to make it run well look over the following link. It needs t-slot restrictions, lowered idle feeds, and opened up angle channels to be ideal.


http://www.motorsportsvillage.com/forum ... f=6&t=3742
T slot restrictions usually kill throttle response ,, might make a pretty dyno graph when the motor gets loaded from wide open though ,, dyno and transbrake only stuff
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Re: Holley 750 Dominator Booster Change Over

Post by 1980RS »

Walter R. Malik wrote: Tue Aug 11, 2020 11:48 am
1980RS wrote: Sat Aug 01, 2020 11:56 pm The 1050 8896-2 test did not work out today. I think it's just too fat and my new parts for the 750 conversion don't show up until Monday. I think using a good 2 circuit with the right parts in it will be better than this 8896. Taking out the intermediate bleeds did help a lot though.
The very ORIGINAL L-8896 was vastly different from those future models with this same number having "dash" numbers.
The original had NO intermediate bleeds at all and the idle & high speed bleeds were "pressed-in".
The intermediate discharge was restricted to .046" and that carb had the older "bar" type boosters.

The bar type booster has an entirely different signal curve.
It is actually stronger at high air-flows but, is not very strong at "pullover" so, the minute amount of fuel delivered by that intermediate circuit was used to fill that hole in the fuel delivery curve.
When the annular booster entered the picture, things about fuel delivery changed immensely but, that carb never really got sorted out correctly.
You are right sir, my old outdated 8896 with the non-A/D boosters worked a lot better out of the box then this newer one. I will keep my eyes open at the swap meets for one or maybe someone will want to swap one for an 850.
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Re: Holley 750 Dominator Booster Change Over

Post by jmarkaudio »

levisnteeshirt wrote: Sun Sep 19, 2021 11:39 am
jmarkaudio wrote: Tue Jul 28, 2020 10:34 am If you want to make it run well look over the following link. It needs t-slot restrictions, lowered idle feeds, and opened up angle channels to be ideal.


http://www.motorsportsvillage.com/forum ... f=6&t=3742
T slot restrictions usually kill throttle response ,, might make a pretty dyno graph when the motor gets loaded from wide open though ,, dyno and transbrake only stuff
If you had built as many Dominators as I have you would understand the need for t-slot restrictions. And in the case of the HP Dominator casting idle calibrations can be all over the place from one to the next, t-slot position can fall from significantly exposed below the closed blades to one I had that was .100" above the closed blades. I test fire and tune every one as needed to get a starting point close for each combination. And I have seen on a pair of Dominators fired one at a time where one had to be calibrated differently than the other to get the same results.

T-slot restrictions are necessary to correct the excessive size of the t-slot on HP castings, and inconsistencies listed above can require different sizes. Most fall in the .059 range, I've been as high as .063 and as low as .047 in one case to get the calibration in a usable range. These are gas carbs, E85 and methanol are going to be different. As far as billet bodies the two I primarily use are very consistent with t-slot size and position, and usually do not need the restrictions as they are smaller, similar to the early non HP castings. The smaller slot always has the best idle and light throttle quality, and it's a noticeable difference. And if you look at some of the newer Gen 3 carbs Holley uses a pressed in restriction in the high .050 range. Throttle response depends on the engine needs, idle feed and idle bleed sizes can be manipulated along with correct t-slot exposure to get the best from it.
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Re: Holley 750 Dominator Booster Change Over

Post by ClassAct »

jmarkaudio wrote: Tue Sep 21, 2021 10:54 am
levisnteeshirt wrote: Sun Sep 19, 2021 11:39 am
jmarkaudio wrote: Tue Jul 28, 2020 10:34 am If you want to make it run well look over the following link. It needs t-slot restrictions, lowered idle feeds, and opened up angle channels to be ideal.


http://www.motorsportsvillage.com/forum ... f=6&t=3742
T slot restrictions usually kill throttle response ,, might make a pretty dyno graph when the motor gets loaded from wide open though ,, dyno and transbrake only stuff
If you had built as many Dominators as I have you would understand the need for t-slot restrictions. And in the case of the HP Dominator casting idle calibrations can be all over the place from one to the next, t-slot position can fall from significantly exposed below the closed blades to one I had that was .100" above the closed blades. I test fire and tune every one as needed to get a starting point close for each combination. And I have seen on a pair of Dominators fired one at a time where one had to be calibrated differently than the other to get the same results.

T-slot restrictions are necessary to correct the excessive size of the t-slot on HP castings, and inconsistencies listed above can require different sizes. Most fall in the .059 range, I've been as high as .063 and as low as .047 in one case to get the calibration in a usable range. These are gas carbs, E85 and methanol are going to be different. As far as billet bodies the two I primarily use are very consistent with t-slot size and position, and usually do not need the restrictions as they are smaller, similar to the early non HP castings. The smaller slot always has the best idle and light throttle quality, and it's a noticeable difference. And if you look at some of the newer Gen 3 carbs Holley uses a pressed in restriction in the high .050 range. Throttle response depends on the engine needs, idle feed and idle bleed sizes can be manipulated along with correct t-slot exposure to get the best from it.
I agree 100%. I just did a tune up on a pair of twin blade dominators and I took a TON of fuel out of the T slots and eliminated the third circuit. I also took some fuel away at idle. It made a car that was stinky rich at idle, puffing blue smoke and was sluggish to drive into something fun.
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Re: Holley 750 Dominator Booster Change Over

Post by levisnteeshirt »

jmarkaudio wrote: Tue Sep 21, 2021 10:54 am
levisnteeshirt wrote: Sun Sep 19, 2021 11:39 am
jmarkaudio wrote: Tue Jul 28, 2020 10:34 am If you want to make it run well look over the following link. It needs t-slot restrictions, lowered idle feeds, and opened up angle channels to be ideal.


http://www.motorsportsvillage.com/forum ... f=6&t=3742
T slot restrictions usually kill throttle response ,, might make a pretty dyno graph when the motor gets loaded from wide open though ,, dyno and transbrake only stuff
If you had built as many Dominators as I have you would understand the need for t-slot restrictions. And in the case of the HP Dominator casting idle calibrations can be all over the place from one to the next, t-slot position can fall from significantly exposed below the closed blades to one I had that was .100" above the closed blades. I test fire and tune every one as needed to get a starting point close for each combination. And I have seen on a pair of Dominators fired one at a time where one had to be calibrated differently than the other to get the same results.

T-slot restrictions are necessary to correct the excessive size of the t-slot on HP castings, and inconsistencies listed above can require different sizes. Most fall in the .059 range, I've been as high as .063 and as low as .047 in one case to get the calibration in a usable range. These are gas carbs, E85 and methanol are going to be different. As far as billet bodies the two I primarily use are very consistent with t-slot size and position, and usually do not need the restrictions as they are smaller, similar to the early non HP castings. The smaller slot always has the best idle and light throttle quality, and it's a noticeable difference. And if you look at some of the newer Gen 3 carbs Holley uses a pressed in restriction in the high .050 range. Throttle response depends on the engine needs, idle feed and idle bleed sizes can be manipulated along with correct t-slot exposure to get the best from it.
One thing i can tell you for sure , every time i drill out t slot restrictions , the guy comes back after he trys it with a big smile on his face. If the IFR is too big or the bleed too small , and the blades fixed where it will idle with the blades shut or almost shut , it seems to work. If not enough fuel comes out of the idle mixture port and something else has to be crutched , so be it ,, sometimes i will make the idle mixture screw restriction to 070. Forcing it to draw more fuel from the mixture screws is what i like

T slot fuel is a good thing IMO , i took a 1250 recently and now the guy can drive it around the pits like it's a fuel injected 4 cyl car , he can't believe it. Most of this billet crap comes with non Holley throttle blades. Change em out and life gets better.

I did a 1050 for this guy but he didn't like it that it had a small leak when i first put it on ,, fixed it quick . He's new to this stuff so he was worried his old carb would leak going down the track at some point , so he bought a new billet 1250 from somebody , starts with an A ,, needless to say it leaked everywhere and we ended up putting the 1050 bowls on it to try it. I have that 1250 settled down and driving like EFI. I really prefer dominators. They're easier to work on and if it's a Holley usually built right and able to get it acting right.
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Re: Holley 750 Dominator Booster Change Over

Post by levisnteeshirt »

jmarkaudio wrote: Tue Sep 21, 2021 10:54 am
levisnteeshirt wrote: Sun Sep 19, 2021 11:39 am
jmarkaudio wrote: Tue Jul 28, 2020 10:34 am If you want to make it run well look over the following link. It needs t-slot restrictions, lowered idle feeds, and opened up angle channels to be ideal.


http://www.motorsportsvillage.com/forum ... f=6&t=3742
T slot restrictions usually kill throttle response ,, might make a pretty dyno graph when the motor gets loaded from wide open though ,, dyno and transbrake only stuff
If you had built as many Dominators as I have you would understand the need for t-slot restrictions. And in the case of the HP Dominator casting idle calibrations can be all over the place from one to the next, t-slot position can fall from significantly exposed below the closed blades to one I had that was .100" above the closed blades. I test fire and tune every one as needed to get a starting point close for each combination. And I have seen on a pair of Dominators fired one at a time where one had to be calibrated differently than the other to get the same results.

T-slot restrictions are necessary to correct the excessive size of the t-slot on HP castings, and inconsistencies listed above can require different sizes. Most fall in the .059 range, I've been as high as .063 and as low as .047 in one case to get the calibration in a usable range. These are gas carbs, E85 and methanol are going to be different. As far as billet bodies the two I primarily use are very consistent with t-slot size and position, and usually do not need the restrictions as they are smaller, similar to the early non HP castings. The smaller slot always has the best idle and light throttle quality, and it's a noticeable difference. And if you look at some of the newer Gen 3 carbs Holley uses a pressed in restriction in the high .050 range. Throttle response depends on the engine needs, idle feed and idle bleed sizes can be manipulated along with correct t-slot exposure to get the best from it.
1 huge problem ,, most people believe their motor has to idle too high ,, get the idle circuit working great ,, they don't have to ,, but it's hard to get people that have dealt with bad carbs to believe that. This is a huge problem with circle tracker guys
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