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 Post subject: Power Valve
 Post Posted: Sat Oct 29, 2011 7:35 am 
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Location: Sharon Hill PA (Phila area)
I have an older 1050. I've been hearing about removing the power valves. What are the advantages, do I remove both primary and secondary, is there anything else that has to be done when they are removed?
496, 13.5 : 1, 722 lift roller

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 Post subject: Re: Power Valve
 Post Posted: Sat Oct 29, 2011 9:27 am 
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If you drag race the car you want to plug the rear/secondary power valve and jet up, anywhere from 4-8 jet sizes on a Dominator. Make sure you have notched rear floats and jet extensions. The issue in the rear stems from the lack of any way to keep the rear PVCR's covered in fuel on a hard launch. Keeping the primary is fine, a footbraked car can run a littl cleaner with one in it. On a well tuned Dominator that runs on a transbrake having the primary PV isn't really necessary. One less thing that can fail.


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 Post subject: Re: Power Valve
 Post Posted: Sun Oct 30, 2011 8:08 am 
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So for racing I should also remove the primary power valve? I will be using a trans brake. Still need a few parts, which are not in the budget right now, before we can get this thing on the track for testing. For a base line, how many jet sizes up should I start off with? If I do remove the primary power valve, I assume I also have to increase the primary jets?
Right now it has 88's primary and 92's secondary. I think right now its running a bit rich, haven't checked plugs, but the exhaust is very sooty. We've only run the motor to break it in, neighbors aren't too crazy about it, but....

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 Post subject: Re: Power Valve
 Post Posted: Sun Oct 30, 2011 9:05 am 
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Word of caution here on jet extensions. DO NOT USE THE SCREW IN TYPE! Ask Beretta about that one! The slip over tube type that are flattened somewhat on the ends where they go under the float are best and will usually work well with the stock type floats that aren't notched.

You didn't specify whether this is a 2 or 3 circuit carb so please define "old 1050" for us with a model number or whether it's a 2 or 3 circuit. Those old 3 circuit carbs are even worse about being rich at part throttle than the newer HP versions. The position of the intermediate circuit dump tube in relation to the throttle blades is the cause of this and even though the new HP carbs have this tube repositioned about a quarter inch up the bore, they are usually still pig rich in the burnout box and on the return road.

I've got an 8896 (old style 1050 Dominator) that I've run on a bunch of different engines. It's been converted to a 2 circuit and it does real well with 92 jet square on most engines. I also run it with a PV in the primary side at times using an 87 PMJ and a 92 SMJ. Your PMJ size would likely be different though unless you've got that 2 circuit tuneup in it from the sticky up the page. The difference would likely be in the PVCR in your carb as opposed to the one in the sticky tuneup that I use.

FYI on engine breakin. Running it in the shop for a short time is OK but in order to help seat the rings faster there really should be a load on that engine, ie, going down the track. If the engine was designed and assembled correctly then bearing problems shouldn't be an issue and track time is needed. Oh, and if that's a 3 circuit carb and it's running real rich at part throttle then the excessive fuel in the cylinders isn't a good thing either as it will wash the oil film off the bores. ;-)

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 Post subject: Re: Power Valve
 Post Posted: Mon Oct 31, 2011 6:07 am 
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Ken, numbers on the air horn: 12R-4325B, the other side reads 622, then LL-FST-4575. If this means anything to you???

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 Post subject: Re: Power Valve
 Post Posted: Mon Oct 31, 2011 9:55 am 
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The list number is 4575 and you've posted that here before back in 07. Not much info after that though and I'm not sure whether it's a 2 or 3 circuit but I'd bet it's the latter. Seems this was the first Dominator that Holley built and it has the tall velocity stacks made into the top of it. There's also some funky stuff on the air bleeds and such but I do remember shrinker making some positive comments about that particular model stating there are certain advantages to running it.

It's listed as having 84 jets front and rear with 6.5 power valves in both ends. For comparison sake, the old style 8896 came with no power valves and 88 jets so one would "assume" that 88s might be a starting point of sorts although I do believe I'd go a step or two richer just to be on the safe side. You're not likely to hurt that engine with it rich but you can hurt it running it lean. I'd start with 90s square with no PV then go to 92s to see if the time slip shows it slowed down and MPH is what you need to look at when doing this kind of tuning. Oh, and make sure you run the same lane at the same track when doing this kind of testing as most tracks are somewhat different from lane to lane.

And while I'm at it, if this is indeed a 3 circuit carb, you might want to go ahead and convert it to 2 circuit before you start doing any tuning. With convention or old style boosters mine uses a 92 jet and I also use those inexpensive QuickFuel billet aluminum metering blocks. There's virtually nothing done in that mod that can't be undone and put back like it is to begin with except for making the air bleeds where you can change them, which should be done either way.

So how good are ya at working with small stuff like this? :-k

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 Post subject: Re: Power Valve
 Post Posted: Mon Oct 31, 2011 4:33 pm 
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I've run my Dominators with and without a PV. To tell the truth I can't tell the difference. Street driving that's something else. In that instancee, a PV would be an advantage.


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 Post subject: Re: Power Valve
 Post Posted: Thu Nov 03, 2011 7:26 am 
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Ok, even more confused now than before. Ken, just because I'm the type that needs to know why, how come you say not to use screw in jet extensions? Can't believe i posted about this carb back in 07, this has been one long project.
Right now I have tons of time but no money to do anything. I'm 5 weeks out from total knee replacement surgery.
So no work = no money....
If anyone has family or friends in the Philly burbs that may be looking for kitchen or bath remodeling, I'd love to have the opportunity to bid the project. Been doing this for 25 years, and the economy, well, you know.....

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 Post subject: Re: Power Valve
 Post Posted: Thu Nov 03, 2011 7:49 am 
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mikef wrote:
Ok, even more confused now than before. Ken, just because I'm the type that needs to know why, how come you say not to use screw in jet extensions?


viewtopic.php?f=6&t=8394&hilit=extensions

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 Post subject: Re: Power Valve
 Post Posted: Thu Nov 03, 2011 8:35 am 
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Push on's it will be

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