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 Post subject: 80186
 Post Posted: Mon Feb 20, 2012 10:21 pm 
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I'm supposed to trick up a 750 Dominator for a friend. He bought it at a swap meet, put a kit in it and put it on his mild 454+.030 BBC. We had also installed a Comp Thumper FT cam. It fired right up and I set the timing with the r's in the 2500 range. This thing was so rich it ran us out of the garage, even though the garage door was open. I'm shooting for these numbers, what do you think?
Idle Jet .040
T slot .062
MAB .026
IAB .065
P Main Jet 70
P PV 45
S Main Jet 75
S PV blocked

Thanks for any help, especially if you've done one of these.
BTW, Do you use bottom taps when tapping carbs?


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 Post subject: Re: 80186
 Post Posted: Mon Feb 20, 2012 10:28 pm 
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Any particular reason you want to keep it a 750 Dominator?

For not much $$ you can replace those flared banjos with some annular ones and make it a 1050. And if I'm not mistaken, that thing is a 3 circuit carb and would be a prime candidate for a 2 circuit swap! =;

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 Post subject: Re: 80186
 Post Posted: Mon Feb 20, 2012 10:49 pm 
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This is a 2 circuit and to be used strictly for cruising around to local car shows. The secondaries might as be welded closed, cause they'll probably never be opened. I have some boosters, but my friend thins the carb is too big even at 750.


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 6:18 am 
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I never used a bottom tap, just went a little at a time till the jet got snug before it's level with the surface..
T-slot jet looks big to me but I may be wrong :-k ...Only have a 52 in my 540 and works fine..I would say it's got to much slot showing so it going to need some holes in the throttle blades. I started with 4 holes 7/64 and went up from there..
Mark should be along shortly I am sure he can get you all the answers you will need =;

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 6:34 am 
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I'm with Barry on the TSJ. Mine has a .055 in it if memory serves. I wouldn't be afraid to go a little small on these and then "sneak up on it" from there, especially with a street engine where you want it lean and clean at cruise.

I'm also larger on the IABs too but they're easy enough to change after it's on and running. Remember also that anything you do with the IABs will likely have some effect on the T slot feeds as well.

Did you check the throttle blades to see where they are in relation to the T slots? As Barry mentioned with his carb, some have had to drill small holes in the butterflies to allow them to close more to cover the T slots. That's a last ditch fix but a fix just the same if that gap is too wide. Barry wound up with 7/64 (.105) holes in his but if you have to drill'em I'd start with an .062 (1/16) and work up if needed. You can always take a little more out of a hole but it's not that easy to put it back. ;-)

On the taps, I use gun taps and grind the point off and make it flat up to the first cutting thread.

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 7:00 am 
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If it's a HP it usually has to much slot with throttle closed O:) ..Did you move the IJ to the bottom of the block??
Get ready to pull it off a 1/2 dozen times or so till you get it right..

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 10:06 am 
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Beretta wrote:
Get ready to pull it off a 1/2 dozen times or so till you get it right..


Isn't that the "fun" part? =; \:D/

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 10:53 am 
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This carb is an old one, no dash anything. I don't know if he set the throttle blades with the slot in mind, but I'd guess that he didn't. I really don't like drilling the blades, I opt for putting 2 jets in the top of the carb and allowing unmetered air to go directly to manifold vacuum. I know Tuner cringes at that, but it's so adjustable with the jets.


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 12:47 pm 
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Ron, I have done it both ways and have to say that holes in the blades are a
better way to do it..
Think about the air being sucked threw that small hole.. It's at super sonic speed O:)
You can also just start with 2 holes in the primary's nothing says that you need
all 4 drilled...
No argument here JMO... ;-)

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 2:02 pm 
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Just so you know I've run the t-slot jets from .052 to .063, it's really dependent on the area of the t-slot and the choice of idle jet and the air bleed to go with it. I had a 1050 recently that had to have a .052 t-slot, .042 IJ, and a .060 IAB. The reason was that the t-slot was placed .100" too high, I had to cut them down to the blades a bunch. This made the t-slot area bleed a lot of air at idle, and made the combination skewed from what I would normally use, but it had to be to make it run correctly. And the first divisional race in Orlando he won Super Street with that carb.... \:D/


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 2:40 pm 
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jmarkaudio wrote:
And the first divisional race in Orlando he won Super Street with that carb.... \:D/

You gotta get some stickers made up, a website and a rake to rake in all that dough.

Do these numbers look ballpark to you?
My old style 9375 3 circuit has HP blocks with
MAB .030
IntAB .070 .039 feed
Idle AB .040 .031 feed
MJ's are 91 square
Squirters .052
and 2 .100 blade bypass jets
My only complaint is that it's still to rich at an idle. Tuner told me that if a race carb doesn't need to be feathered until it's warm, it's rich. This one doesn't need to be feathered much. Also, after a run or 2, the idle speed goes way up.


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 3:52 pm 
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If that is an old style 9375 someone messed it up. The original calibrations were not real bad, a little rich in the mid due to the intermediate circuit but usually tolerable. I'm assuming from the odd sizes the bleeds have been threaded for replaceable bleeds, run the MAB's at .026 to start, take out the intermediate air bleed altogether, and go up on the idle bleed until it surges or stumbles when on the transition circuit then back down a little to clear it up. Make sure the t-slot exposure is good or you will fight the tune. And unless the engine tune is off I usually don't need more than .035 for squirters with gas, I have even run a white 30cc pump cam (modified for a Dominator shaft) on the primary side to cut the accelerator pump fuel. It will help if you can kill the intermediate fuel altogether, you would have to thread the metering block either in front at the metering jet or on the back side where it meets the intermediate tube. I would rather make one a 2 circuit, as you can put the idle feed down low.


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 4:07 pm 
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fourtenposi went round and round with Dominator pump cams, ie, MODIFYING his own with a file to make them work (taking away fuel) and he has O2 sensors on both sides of the engine to KNOW what he was doing. I know he finally got it close at one point but he's like the rest of us in that he never leaves it alone and has more than one carb that he runs.

To be honest, I was thinking today that I need to do some tuning on my pump shots as I've only been looking at AFRs down track AFTER the gear change to see where I was at. Having said that, I'm sure there is more performance to be had in the short times by leaning a Dominator pump shot at the hit.

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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 5:27 pm 
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jmarkaudio wrote:
If that is an old style 9375 someone messed it up. The original calibrations were not real bad, a little rich in the mid due to the intermediate circuit but usually tolerable. I'm assuming from the odd sizes the bleeds have been threaded for replaceable bleeds, run the MAB's at .026 to start, take out the intermediate air bleed altogether, and go up on the idle bleed until it surges or stumbles when on the transition circuit then back down a little to clear it up. Make sure the t-slot exposure is good or you will fight the tune. And unless the engine tune is off I usually don't need more than .035 for squirters with gas, I have even run a white 30cc pump cam (modified for a Dominator shaft) on the primary side to cut the accelerator pump fuel. It will help if you can kill the intermediate fuel altogether, you would have to thread the metering block either in front at the metering jet or on the back side where it meets the intermediate tube. I would rather make one a 2 circuit, as you can put the idle feed down low.

Those numbers are exactly the way Ken Jones gave the carb back. It was pig rich before he messed with it. It seems to run good to me, but it seems a tad fat on the idle circuit. Ken had 35 squirters in it, but it wouldn't leave so I started going up. It left good when I got to 52. He told me there was no way I should need a 52, but they're still in there. I was going to convert it to a 2 circuit and somehow got to talking with him about my conversion ideas. He told me to leave it as a 3, but put the newer blocks in. He told me the intermediate circuit does almost nothing the way he sets them up. So I asked him if he wanted to do this one. I have some 7320 blocks that I was going to use to make a 2 circuit. If I use the 7320 blocks and the right gasket, I'd have a 2 circuiit in a hurry. Maybe I'll try it once the season starts. I have the 7320 main body, but I'm thinking 1150 is a little much for my engine. I talked to BLP a year ago about using a skirted booster to try to get the cfm's down a little on the 1150. I'd rather have a second carb, in case I need to throw the Ken Jones back on cause I know it'll go down the track.


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 Post subject: Re: 80186
 Post Posted: Tue Feb 21, 2012 6:41 pm 
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The 7320 blocks will work, just lower the idle feed, and look over the 2 circuit thread, you need some jets in the t-slot passage of the main body as well.


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