Does anyone else have a Fuel Curve Engineering preped 9375 Dominator. I had it set up for street/strip use. Plugs foul often, and am getting ready to make a carb change. Any carb suggestions? 464, Stg.2 fully ported early open chamber tall port heads, 308s, TH400, 3:90 gears, 3770lbs.
I used pro systems, and idled like a stocker and was within 1-2 jet size, midrange very crisp. Highly recommend!
I,m guessing you are talking about Fuel Curve in So. Calif. If you are did you call Dave and talk about plugs, fuel pressure and a jet change. Obviously something needs to be changed but not necessarily the carb.
If you do go with a new set up I too recommend Pro Systems. Patrick is a wizard and had our 1050 nailed down the first time. Besides jetting for air I never have to touch it.
Thanks, I'll look into the Pro Systems setup. Also, I never heard of a Dave at Fuel Curve Engineering, I always used to talk to a Bob Szabo there. I am not sure he is still doing the carb thing anymore. I know he closed up years ago, though if he re-opened, please let me know. Thanks, Larry
Lawrence, It sounds like your carb just needs an air bleed change. A good carb guy in your area should be able to help you with this. ---------- Post added at 05:57 PM ---------- Previous post was at 05:57 PM ----------
You should think about putting in a A/F meter works wonders I completely redid my 9375 with it, although I drive it on the street, I switched it over to a 2 circuit much easier to drive. I have almost the same set-up as yours.
I ran that same # Holley right out of the box with only minor jet changes to get it dialed in and NEVER had any fouled plugs or other problems. It ran well and idled great. Was on a iron headed 464 with a KB cam and Wildcat intake for a Dominator. People thought I was crazy putting it on a nearly stock engine but it worked and proved to be faster than several 4150s I tried including customs. Jim N.
Two different Fuel Curve companies, Dave Lange is at Fuel Curve West in Upland,Calif. and Bob Szabo is in the southeast, original shop was in North Carolina.
I second the vote for a Wideband O2 meter. Widebands are getting cheaper all the time. The GN guys have been using them for a while, but they are an invaluable tool to sort out a carb. Most stock Holleys are setup pig rich out of the box. Your tuner carb could be the same. Check Innovate Motorsports.
I have a wideband O2 from Innovate. It failed once, replaced it, but otherwise I like it. It is very helpful. I've found that if you're not close on jetting, even reading plugs can be difficult. A few things to check if you're excessively rich at idle (before changing the air bleed): 1) float level - easy to check 2) excessive fuel pressure can cause such a thing 4) Make sure your power valve is not opening at idle. should be chosen to be about half of idle vac. 5) Make sure you're not in the transfer circuit of the carb due to excessive throttle plate position (idle setting). You should only be able to see a little bit of the transfer slot, maybe 0.030" or so. If you are, you may need to adjust the secondary throttle plate position at idle to better match the primary, allowing you to close the primary plate a bit, cover the transfer slot, and still maintain an idle that works with a big cam. *** this one is often overlooked*** 6) Air bleed change, as John mentions above. Good luck Ben
Lawrence, Ben brings up a good point with a dominator. A dominator carb is supposed to be treated as two separate carbs. A front half and a back half. Therefore, if the front idle screw is opened 1 1/2 turns then the back idle screw should be open 1 1/2 turns. In many instances the front idle screw will be open 3 turns and the back 0, which puts the front butterfly open into the transfer circuit!!!
Thanks to all, great info! The last few posts hit it on the head, I checked and they were 3-full turns in front, 1-full turn in back. That exposed the mentioned transfer slots in the primaries only. Now that the carb is in order, I have found another issue that may have been mistaken as fuel fouled. After looking down the intake runners with a dental mirror I found the runners to be as dry as a fart in the wind. So I started looking at the plugs closer ( with my glasses on) and they are still wet, a month later. I should have put my glasses on a month earlier, they are oil fouled, threads are wet too. I believe its time to start a new thread. Once again Thank You for the information on the carb, I'm sure when I get over the next issue the transition circuit should be tame. Larry
Ever wonder how the 9375 got started with Buicks? Kind of interesting story of the probable cause on how many of us wound up with the wrong dominator (9375). Here are the highlights of the story. In 1992 when Dave Benisek was dyno testing his engine for the upcoming GSE or GSP class at the GS Nationals, he had heard Grumpy Jenkins was using two 9375's on his twin carb, tunnel rammed Pro Stocker. So Dave ordered one. In attendance at the dyno session was Jim Bell, Dave Benisek, Bob Leonhart (local engine builder) and Doug Jones. They first tried a Q-jet then a thermoquad and then a modified holley 850. For the last pull they installed the out of the box 9375. The engine picked up 40 hp! The choice was simple and at the 1992 Nationals they showed up with the first in their class, and most likely at the whole event, Dominator on a Buick. When people saw how quick the car was, it had the only Dominator in the field, the part number was a 9375, it became the new go-fast item to have on their Buick. My personal experience was that I borrowed one of these 9375's from a Buick friend in 1997 and installed in on my low 12 second Buick. I took the car to Bakersfield, CA for a local club event and made my first 11 second pass. My car picked up an easy 3 tenths of a second over the Q-Jet. So I quickly ordered a new 9375, never questioning if it was the right one, and installed it on my car and never looked back. I made the same mistake as everyone else.
So,what makes the 9375 wrong? I've seen lots of debate about switching the 3 circuit to 2 circuit as well. I have one and it's never been quite right,mostly a flat spot off idle. I foot brake the car,and getting it off the line can be a challenge. That being said, I'm no expert on carb tuning even though I've been racing half my life. Always open to try new methods.
Well, I never knew that the 9375 was a "Buick" carburetor, I had a friend at Holley and since this was a school project car they wanted to give us some help and gave me the 9375, it was not like I went out and picked it out. This was in 95 and like others said, it was a great bolt on and mine never had any issues, no flat spots, no stumble and I was running with a tight convertor at the time. I have always liked the big carburetors and have run a couple of numbers since. Now I will have to look at it to get the # but I have one of the very first Dominators that came out, it even has a choke. I can't remember for sure but I believe someone said it was from a Boss 429 Nascar deal. Another reason I wanted one was that I helped a student run a BBC back in the 70s and we ran one and everyone thought he was crazy until he won 2 track championships in one year and you should have seen the people scrambling to get them one. Jim N.
It's "wrong" because it's designed for a dual quad setup on a tunnel ram. That setup needs sensitive circuitry in the carb to get decent response...thus the 3 circuit and no power valve. I think the reason it works so well on Buicks is that we usually don't have a lot of converter and need a big carb that responds well at lower rpms. It also make it a bit better on the street with the 3 circuits (with a few mods) than the 2 circuit models. When I stage my cars (both have relatively low stall converters....4200 flash) I go to 2000-2200 at the line until I hear the motor get a little lumpy from the second circuit richening things up. Then there is no bog at the launch. If you don't get the motor on that 2nd circuit (still on idle circuit) it will BOG! It has happened to me a few times when the air is real good or at Cecil. I was able to stage while still on the idle circuit. BTW I've always found the 9375 to need bigger jets than out of the box. (stock 88s jetted up to 92-94s) I figured they were jetter leaner due to being for dual quads......
