dominator on a 540
 

I have been having a hell of a time tuning my new mill....I have had people tell me pull the power valves and some say leave them in.................................Can someone please tell me what a na 540 9.5 to 1 comp, with a dominator braswell 1050 , where i should strart as far as power valves and jetting.........I tried to use the block offs and i am at 91 jets now and still to lean...........Help please..................


I am so close...........

Use a power valve. You can do a search on here for power valves & you might get some better ideas as to which one you will need to start with. I would start with a 4.5. A 4.5 will open when the manifold vacumm goes below 4.5"

97 squared and #5 power valves is what i run on a 454w/blower.

first of all is this a 2 or 3 circuit Dommy?? marine specific carb??

muy' importante' question.....

It is actually a brasswell, i am at the point i need a new baseline to start from........1050 need guys that run a 540 with big a cam good guts and great exhaust.........No power valves has been killing me i cant tune this bastard.......



HELP PLEASE, TYLER,TOMMY,JC,ANYBODY !!!!!!!!!!!!!!!!

you didn't answer my question..

There are many different Dominators set ups. However most of them seem to come from Holley with square jetting at 90 and #6.5 power valves. Since you have 91's and no power valves, it would seem that you are lean. A power valve adds about 6 jet sizes. Teague, in one of his tech articles in Powerboat mag recommended a 8082-1 Holley 2 circuit 1050 with the addition of 2.5 power valves as a good carb for a high perf. 540. Mine has 92 jets and 3.5 power valves.

this is a very good suggestion, provided you have a TWO CIRCUIT Dommy. If you have a 3 circuit, you'll NEVER get it tuned right......

JH

Mine is a Holley Dominator 1150 CFM #7320 (2-circuit) with 87 X 87 jets and 3.5 PV.
With a big cam, you may also need to reduce the idle air bleeds 3-5 sizes (richer) if a high idle setting in neutral is causing you are opening the throttle blades to the point of pulling fuel out of the transfer slots. A good indicator will be if the 4 corner idle screws are unresponsive.
I agree with the comments on a 3 circuit carb...sell it!

According to Teague, in the same tech tip, 3 circuit will always run too fat in the midrange.

2 circuit is the way to go. You may need to change the air bleeds. Do you have bungs in your exhaust to run an AFR meter such as a FAST? If not.....you are pushing rope.

sorry.........I guess i am not familiar with the circuit deal......I dont know what the difference is between a 2 and 3 circuit...

I was a rope pusher for years...the Innovate Motor Sports LS-1 move the dyno based jetting from 93X95 to 87X87 with a new safe A/F ratio of 13.6 13.7 in the mid range and then 12.5 at WOT (above 5500 RPM w/PV open). With todays cost of fuel, it is a huge waste to be super rich in the mid range.
Jetting on the dyno likely lead you down the wrong path.

I would think you could hook up a vacuum gauge to the port under the carb, if not one there drill and tap one so you can get a vacuum reading for what the carb is seeing. Then you can tune your power valve according to when you need it to come in. Also power valve transfer slot holes, which are the small holes when you take out the power valve, can be enlarged to add more fuel thru the power valve. You could then adjust it to work on richening up your motor at pure WFO without fattening up the middle, by selection of your power valve size.

What language is that..............

I am still new at the tuning thing, i went out today after work and bought 5.5 and .6.5 pv's from the way it sounds i should maybe leave the jets where they are at 91 and put the valves in?

You're saying you have too big a cam. A 6.5 power valve may open when you shift gears (At 6.5 inches of vacuum) causing the engine to stall. That's why I use a 3.5. It waits until the vacuum drops lower before opening. Even a 3.5 will open long before you get to full throttle. It helps to have a vacuum gauge to tune it ocrrectly.

I drilled and taped a fitting in the carb just now, when i hook a vacuum gauge to it how will i know if i need a3.5 4.5 or 5.5 or 6.5...........

With a vacuum gauge uou will know when the power valve opens...but opens to what AFR? Still pushing rope...

Put bungs in your tales and get a double barrel Fast off of Ebay. You will thank me later!

1050 80340 marine carb 2 circuit. Motor is 572ci 9.25 to 1 compression, 5 inch exhaust, dart 345 heads, roller cam 139651 632 lift, 96 square jetting, 6.5 power valve in the front primary and 6.5 power in the back valve in the secondary.

That is where I wound up with the carb. Also 71 air bleeds were in the idle circuit which went to 57 and finally ended up at 51s. Idles perfect in and out of gear perfect.

I had Barry grant 1090s which if anyone wants a deal on these carbs I have 2 with 10 hrs for $600 each paid a $1000.

Thanks i am going to start with the 6.5 and 91 squared first to see where i am at....................



I DONT SAY THIS ENOUGH BUT THANKS GUYS,,,,,,,,,,,I COULD HAVE NEVER DONE WHAT I HAVE DONE WITH THIS MAG WITHOUT OSO MEMBERS...........

Nocig,
Most of the post here are referencing set ups on 2-circuit Holley's. If your Braswell prepared carbs are 3-circuit (the 3rd circuit adds WAY too much fuel in the mid-range), none of these 2-circuit set-ups will apply. Many, including the experts like Bob Teague, have given up trying to get 3-circuit Dominators to work in a marine application.
If your carbs are 3-circuit, consider getting Braswell to change out the metering blocks and convert these carbs to 2-circuit. I am pretty sure this can be done and is an easy fix.

I am almost positive it is a 2 circuit because i bought it with a complete marine engine package.......At least i hope so........nobody has told me how to tell the difference between 2 and 3 circuit though.....

what's the list # for your carb, we can solve this in 30 seconds...

On the top of the carb are a series of brass screw in air bleeds; they look like fuel jets. On the top front and top back of the carb there are are a series of these air bleeds. If there are 6 air bleeds front and 6 back you have a 3-circuit; if there are 4 air bleeds front and 4 back it is a 2-circuit.

2 circuit, just four................and thats ben perfected ?????????/

These guy know their shzit!:D

80340 holley 94sq 4.5 pv I HAVE 540S WITH MERC 900 CAMS AND DART INTAKES IDLES AT 950 RPM AND IN GEAR 800 THESE CARBS WORK PERFECT.