Dominator on 572 street/strip engine

[hemicharger572]

Hi guys,
I have read a lot of about the carburator settings on street/strip hemis around here.

I have build a new 572cui indy maxx aluminum hemi this winter.
engine data:
572 cui
10.25 compression ratio
Indy Maxx Aluminum
diamond pistons
molnar rods and crankshaft
cam data: dur .050: 282 / 282
lobe lift: 4000 / 4000
lobe seperation: 109
rocker ratio: 1.6 / 1.6
> Ray Barton rocker system
Indy HiPo heads
Ray Barton single plane intake for 4150 carburators
Quick Fuel Q-Series 1050cfm anular boosters
Dana 60 > 3.72 gears
3000-3500 stall speed ATI treemaster converter
727 torqueflite with manual valve body reverse pattern, equippet from A and A racing parts

in a 69' Dodge Polara

I know its not a B-body, but nobody in the FCBO could help me. I hope its ok that I am asking in the FBBO forum.

so here is my problem:
when I go down the track, in first gear the rpm goes really quick up to 6700 rpm and more if I would.
If I shift in 2nd and 3rd gear the rpm drops to 4500 rpm. The combustion at WOT is fine. The AFR stays at about 12.5.
This weekend I tried out a friends carb. Its a 1050cfm downleg Holley. With this carb I could go in 2nd and 3rd gear 5200 rpm at almost the same AFR.

That sounds to me like that I have enough fuel at WOT because AFR stays at 12.5.

To my mind the engine just don't get enough air through the carburator. Thats why I want to try a bigger carb.
I want to stay with the single plane Ray Barton Intake.
I already have an old 1250cfm Holley dominator.

Would you guys think this could be a possible reason why I cant raise the rpm in 2nd and 3rd gear? And because its still a street car and weekend racer, does anybody drive a big dominator on the streets as well?

Thank you very much,
Michael from Germany.

 

[lewtot184]

my guess would be annular vs down leg boosters. i wouldn't think you'd need annulars on 572 cubes and that small of a carb for 572 cubes.

 

[Tempest 455]

Did you check float level on both? How much fuel pressure and gph?

A Dominator will run just fne on the street with that cam if you dial it in for the combo.

 

[hemicharger572]

my guess would be annular vs down leg boosters. i wouldn't think you'd need annulars on 572 cubes and that small of a carb for 572 cubes.

If I understand you right, you think the carb is to small and downlegs would maybe be the better choice?

 

[hemicharger572]

Did you check float level on both? How much fuel pressure and gph?

A Dominator will run just fne on the street with that cam if you dial it in for the combo.

Yes, floatlevel covers about 50% of the showglas on the primarys, secondary about 60%

Fuel pressure at idle: primary: 8psi
scondary: 7 psi

Its a black holley electric fuel pump
in combination with the aeromotiv bypass A2000 fuel pressure regulator. Fuel comes and leaves the regulator with a 10AN fuel line. Two 8 AN's from the regulator to the carb.

Last week I have changend the regulator to the aeromotiv. But nothing has changend.

I degreed the cam to the data on the cam sheet.

Edit: its a solid flat tapped camshaft

 

[HEMI-ITIS]

Did you check float level on both? How much fuel pressure and gph?

A Dominator will run just fine on the street with that cam if you dial it in for the combo.

You have all that you need to have fun.Dial in your carb and have fun!! Your shift point is determined by the cam,,,,not the carb!

 

[lewtot184]

If I understand you right, you think the carb is to small and downlegs would maybe be the better choice?

i would use annular's with an engine that might be a little small for the carb; i don't think you have that problem. i do think the carb is small for a 572 and the engine would be a perfect candidate for multi carb. what i would do is call quick fuel for some expert advice. another thing you can do is hook up a vacuum gauge and check the reading at a full throttle pass. i wouldn't be surprised if the vacuum wouldn't read 1" or more at 6000rpm.

 

[383man]

If you have a 1250 dominator and its a good carb why dont you try it ? Will it fit under your hood if you have to use the adapter for the dominator ? Putting a vacum gauge on and making a WOT pass is a good idea to give an indication of to small a carb if you see vacum at WOT and high rpm. Your A/F ratio can be ok but still may not be enough of both at WOT. You can have a 12.5 A/F ratio even at idle but of course to keep the same at WOT you need much more of both so even with to small a carb you could still get a decent A/F ratio if the jetting is set to the small carb. Ron

 

[Tempest 455]

You have all that you need to have fun.Dial in your carb and have fun!! Your shift point is determined by the cam,,,,not the carb!

Not if you run out of fuel. LOL

The way I read it, he tried another carb and those were the results. Don't care if you have a 318 cam or a .750 lift/280 deg solid roller. If you run the bowls dry, the motor is not going to pull. Check the basics 1st.

 

[dvw]

Are you saying it won't pull past 5200 in 2nd or 3rd? Or are saying it drops to 5200 after the shift (that would be true stall speed of the converter)? If it won't pull past 5200 I'd do a fuel delivery test. Gas weighs roughly 6lbs/gallon. You need roughly .5lbs per HP per hour. You have plenty large enough fuel line, maybe not enough pump or tank vent. For what it's worth I feel you have to much duration for 10.25-1 compression, especially on the street. Heck my 3350lb 572" drag car at 15-1 is only [email protected]")
Read here about fuel delivery
http://www.enginelogics.com/fuel-pump-sizing/
Doug

 

[SUPERSTOCKRACER]

so here is my problem:
when I go down the track, in first gear the rpm goes really quick up to 6700 rpm and more if I would.


^^^
Are you sure about this stall speed?
Sounds like you have transmission problems or a very very loose converter. My converters only stall around 5800 to 6000 rms

If I were you, I'd go on the street and lay into the throttle slowly to 6200's and shift into second and see if it noses over or flat out cuts out.
Report back.

 

[Bigal75]

I run a 1050 dominator with custom 20 hole annular boosters on my street car. 750 hp. Works like a dream. My biggest issues have been fuel delivery. You'll need an adapter or another intake to run the dominator.

I got my carb set up from a guy on Yellow Bullet...Mark Whitener I believe. He knows his stuff!

 

[kjalltrac]

I had a problem with a faulty ignition box last year, rewed fine in first or neutral, lost power and rpm in sec and third gear, the problem went away when I changed the ignition box.
Just a thought...

 

[hemicharger572]

Are you saying it won't pull past 5200 in 2nd or 3rd? Or are saying it drops to 5200 after the shift (that would be true stall speed of the converter)? If it won't pull past 5200 I'd do a fuel delivery test. Gas weighs roughly 6lbs/gallon. You need roughly .5lbs per HP per hour. You have plenty large enough fuel line, maybe not enough pump or tank vent. For what it's worth I feel you have to much duration for 10.25-1 compression, especially on the street. Heck my 3350lb 572" drag car at 15-1 is only [email protected]")
Read here about fuel delivery
http://www.enginelogics.com/fuel-pump-sizing/
Doug

I am saying that it wont pull past 4500 rpm with my quick fuel (annular) in 2nd and 3rd gear. With my friends carb (downleg) I was able to go up to 5200. But couldn't pass it eather.


The cam, the big valve heads in combination with 1.6 rocker ratio runs really really nice on the street. Way better than my old 572 which I have sold (it was the mother thumber hydraulic cam and edelbrock heads--never again).

Thanks for the link

 

[hemicharger572]

[QUOTE\]Are you sure about this stall speed?
Sounds like you have transmission problems or a very very loose converter. My converters only stall around 5800 to 6000 rms

If I were you, I'd go on the street and lay into the throttle slowly to 6200's and shift into second and see if it noses over or flat out cuts out.
Report back.[/QUOTE]



I dont think it's the transmission.
Because on my old 572cui I already had the same problems.
On the old engine I have tried out many different kinds of intakes and carburator(s).
Way ago, I had a dual plan intake with 2x650cfm edelbrock carbs. At this time I was able to reach the 6500 rpm+

Then I have changed to the single plane intake with the 1050cfm carb.
After that I couldn't go over 5000rpm.
At low rpms the power and torque was so much higher than on the old set up.

After I have build the new hemi engine, the only thing in the hole car what I have used again was the single plane intake and the quick fuel carburator.
>> the new engine with the new components runs much better than the old one, but again, still have the same problems at higher rpm. > thats why I, and many of you guys, think that my carb is to small. On top of that, the car runs a little better with my friends carb.

I also have a new transmission, new ATI converter.
The ignition was upgraded from mopar ignition box and mopar distributor to a MSD 6AL and a MSD distributor (without vacuum advance).


The new engine already have much more power.
Last weekend I was testing at the 1/8 mile strip.
With 10 years old street tires and wheel spin to the half of the track, I did a 8.2sec.
60ft: 1.54 sec
My old best was a 8.1 with slicks.


So tomorrow I will order an adapter for the 1250cfm dominator that I already have (it runs on my brothers cuda, I can steel it for a while )

Then it takes about 2 weeks until its over here.
Then I start testing.

Thanks guys

 

[Hemirunner]

I would think your rev limiter is that small exhaust choking it. Get that off of there. It's a nearly 600" engine and it needs to breathe.

 

[Bigal75]

I had a 140gph fuel pump and there's no way it would keep up. Are you sure you have enough pump? I needed a 250gph for my set up that probably makes less power than yours.

 

[Bigal75]

I re-read your posts. Sounds like it's running out of fuel. Mine was an animal in first gear and then would get lazy in high gear. Wouldn't pull past 5k either- at all. Check your fuel filters and make sure they flow enough. I just went through that as well. What's a holley black pump flow? 150gph at what psi?

BTW a 1050cfm 4150 is not a 1050 4500.

 

[Bigal75]

Are you saying it won't pull past 5200 in 2nd or 3rd? Or are saying it drops to 5200 after the shift (that would be true stall speed of the converter)? If it won't pull past 5200 I'd do a fuel delivery test. Gas weighs roughly 6lbs/gallon. You need roughly .5lbs per HP per hour. You have plenty large enough fuel line, maybe not enough pump or tank vent. For what it's worth I feel you have to much duration for 10.25-1 compression, especially on the street. Heck my 3350lb 572" drag car at 15-1 is only [email protected]")
Read here about fuel delivery
http://www.enginelogics.com/fuel-pump-sizing/
Doug

11:1 572 with a 283/283 cam. Works great with a 4k stall.

 

[hemicharger572]

I would think your rev limiter is that small exhaust choking it.Get that off of there. It's a nearly 600" engine and it needs to breathe.

the exhaust starts with a 2 1/2" pipe, gets over in a 4" pipe and ends up in a 3" exhaust. During racing I have the cut outs open. I had to smash and bend the exhaust on a couple spots, but a while ago the Hot Rod magazine I guess, did a really nice test on a dyno. They figured out the difference in horsepower and torque between brand new headers and totally smashed headers. Very surprising, almost no differences.