GatorDog72 Posted September 7, 2016 Share Posted September 7, 2016 I've had my car on the road a few times now since getting it together. I drove it to work this morning (about 40 miles, there and back) and got about 5 mpg. The car runs very well overall but seems a little sluggish if you stomp the gas from a standstill. I pulled the plugs and they are all black and fouled so it's definitely running very rich. Smells like fuel too. The carb is a 1050 Ultra Dominator with 2 circuits, part # 0-80902HB. It's on top of a 489 big block with a 250 duration @.050 solid roller cam, 10.5:1 compression. I was amazed at how well the car ran with this carb straight out of the box. The only thing I have touched is the idle adjustment. I had to turn it down some to get it to idle. It's at 6 psi fuel pressure, idle screws 1 1/2 turns out, and the floats are set so fuel is half way up the sight glass on the front bowl, and a little over half on the rear. I'm not sure on the main jet size or the power valve. I'll have to take it apart. So where should I start with this thing? There's lots of stuff to play around with, not sure what to do first. The engine runs pretty well, it's just drowning in fuel. I know they say you cant get these carbs to run on the street, but I'm going to try anyway. Sorry for the novel I wrote, any input and comments appreciated. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 7, 2016 Share Posted September 7, 2016 I am very good with 4150 carbs so I think I can apply that to a 4500 Dominator raise the fuel pressure to 7 psi first (I run 7.25 on my Pro-Systems 4150) then lower the float levels to 1/4 in the site glass (anything over 40% in the site glass can start pulling fuel from main metering way to soon, even at idle) your base timing with your engine will need to be around 20 BTDC test drive it next, if it's still way rich, take some fuel out of the intermediate circuit first, while cruising you are mainly running on the intermediate circuit, I'm not sure if a 4500 even uses a Power Valve but we'll look at the later Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 11, 2016 Author Share Posted September 11, 2016 I reset the floats and adjusted fuel pressure and it's still really rich. It loads up at stop lights and it won't restart once the engine is warmed up. I have to wait about 15-20 minutes and then it fires right back up.(this might not be fuel related but probably is) I got some more info on this carb. I was reading about how to tune the intermediate circuit and found that my carb doesn't have one. There's only 8 air bleeds in the top. I guess that's the difference between the 2 and 3 circuit carbs is that intermediate circuit. Sounds like a 2 circuit Dominator is basically just a really big 4150 double pumper with no choke. Hopefully this will simplify the tuning. I ordered a bunch of jets and bleeds to get started. It has 84/94 main jets, 5.5 powervalve, and a 35 primary pump nozzle. I'll be installing a wideband o2 sensor while I wait for the jets to get here. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 11, 2016 Share Posted September 11, 2016 2 circuit cool! post a picture of it if you can how far out are your idle screws? what size are the idle air bleeds? I can get this real close without a A/F meter Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 12, 2016 Author Share Posted September 12, 2016 Thanks for the advice, Sam. I tried playing with the idle mixture screws when I adjusted the floats and it didn't respond much to anything I did. I believe they are all at 3/4 turn out now. I wish I knew the size of the idle air bleeds, I haven't taken them out yet. Figured I would take the whole carb off so I didn't drop the jet down the manifold like an idiot. I think they are .070" but I don't know for sure. Here's some pictures of the carb and what the plugs looked like. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 12, 2016 Share Posted September 12, 2016 Up the idle air bleed .010 Looks like you need a hotter plug too Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 12, 2016 Share Posted September 12, 2016 How much initial timing you running? Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 12, 2016 Author Share Posted September 12, 2016 I set the initial timing at 24 degrees BTDC. Had it locked out at 36 but had to run a timing curve for pump gas. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 13, 2016 Share Posted September 13, 2016 that's close, what happens when you turn the idle screws in more? I'm almost considering you may need to put a smaller idle feed restricter in it Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 14, 2016 Author Share Posted September 14, 2016 Got a little more seat time today, drove it to work. It ran like poo. It's loading up at part throttle cruising and idle and starts to misfire. When I got home I played some more with the idle mixture screws and the more I turned them in, the higher the idle went. It got so high that I had backed completely off the curb idle adjustment and it was still way high. At this point I thought there was a vacuum leak or something else funny going on. Apparently there is an adjustment screw on the passenger side of the carb for the secondary butterflies. It was screwed way in causing it to pull a ton of fuel off the secondaries at idle. After I corrected this adjustment, the idle smoothed out and the black smoke went away. I'll have to take it for a spin and see how it runs now. I cleaned off a plug just to see where its at until I get a new set. Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 17, 2016 Author Share Posted September 17, 2016 I drove it around some more and it seems a little closer but still rich. The idle cleaned up quite a bit, but its still misfiring at cruising speeds. The plugs are still black but not wet anymore, I'll try going up in heat range on the plugs and start fooling with the air bleeds after I see what they look like. This is what the plugs looked like after I adjusted the throttle blades. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 17, 2016 Share Posted September 17, 2016 hold off on the plugs for now with the engine warmed up.... close both throttle blades completely, then open both of them 1 full turn and try to start it and see if it will idle, start with your idle screws at 1 1/2 turns out open and/or close both the same amount to get it to idle, then start adjusting your idle screws, turn each in 1/4 turn at a time until the idle starts to drop, then open each one back up 1/4 turn, if the idle screws are less than 1 1/2 turns out, you need to put a larger idle air bleed in it, start with .010 larger Quote Link to comment Share on other sites More sharing options...
GermanMonte Posted September 20, 2016 Share Posted September 20, 2016 I know the more experienced carb guys may see things differently, because they got carbs right even before I was born, but get yourself one or better two A/F widebands and a vacuum gauge. It makes tuning a carb so much easier. I've spent almost two years of tuning on my QuickFuel SS750 carb on a 427 SBC with the help of two A/F gauges and some very experienced guys from this and the Yellowbullet forum. The A/F gauges help you to see the effects of little changes and modifications and take out a lot of guesswork plus the experienced carb guys can tell you which way to go once they see your readings combined with the corresponding engine speeds and load levels. Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 23, 2016 Author Share Posted September 23, 2016 I think I'm getting much closer. I found out the misfire was due to a spark plug wire melted to the headers. Also found out the idle air bleeds were .057" not .070" like I thought. I changed those to .067". Idle mixture screws now like to be at 1 1/2 turns out. It runs great now and it's more responsive than before. I had to go up a heat range in plugs because the auto parts store was out of the plugs I needed. Went from an Autolite Racing AR3932 to AR3933. The plug in the picture has about 20 minutes of run time with some cruising and one good pull through the gears. It looks a lot cleaner than before. Like GermanMonte said, I may have to hook up my A/F meter to see where it's running before going any further. Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 26, 2016 Author Share Posted September 26, 2016 Got that meter hooked up today and its working nicely. At my current settings it was reading about 13.5:1 at idle. I tried leaning it out some more to around 15:1, but it didn't like that adjustment. Every time when coming to a stop the engine would go way lean and stall. Almost like the floats are too low or something. I put the mixture screws back to where they were and it runs fine. It shows 11-12:1 at WOT, and 13:1 part-throttle while cruising along. The sensor may not be accurate at idle. I put it in the side of the collector then found out after I read the instructions it tells you not to put it there. It should have been in a single exhaust tube. Not sure how much it will affect it. Quote Link to comment Share on other sites More sharing options...
GermanMonte Posted September 27, 2016 Share Posted September 27, 2016 The sensor should be a little bit behind the collector in a 9 - 3 o'clock position for the best results. I'd say you can use it where it is now to get the first results. 13 at cruising speeds is a tad rich. I'd shoot for around 14 at idle and 14-15 at cruise. There's no need of flooding the engine with gas at very low loads cruising around. You can go up on the idle air bleeds to lean out your cruise or down on the idle feed restrictors. I had the same "going lean while coming to a stop" condition before I put the idle feed restrictors from the high position to the low position in the metering blocks. With a big cam and low vacuum the engine has a hard time pulling the fuel up the idle well. Lowering the IFRs sure helps! What do the readings from cruise to part throttle look like? Does the idle / transition circuit blend into the main system properly without going rich as hell? Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted April 16, 2017 Author Share Posted April 16, 2017 It's finally warm enough to drive the car, so I'm going to continue to get this carburetor dialed in better. It's much closer than it was out of the box, but its still rich at part throttle cruise and WOT. I'm getting around 11:1 on the highway cruising around 5% throttle, and around 12:1 when I floor it. I'm thinking to drop a couple jet sizes on the mains on both the front and rear blocks, then see where its at. As I started leaning the fuel curve out, I noticed a new problem. With the RPM that this engine turns at higher cruising speeds, the water temp starts to creep up higher into the 210's- 220's until I slow down and turn the electric fans on. I may need to install a larger radiator to keep things cooled off. Overall the car runs well. It's not blowing black smoke everywhere and throttle response is good, but I know there's more in it. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted April 16, 2017 Share Posted April 16, 2017 with it being a Dominator 3 circuit carb, I would try a larger intermediate air bleed, when cruising that's where it's pulling fuel from, that may also help lean WOT A/F ratio Quote Link to comment Share on other sites More sharing options...
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