When you get right down to it an 850 is a really good carb. A well tuned 850 will outperform a poorly tuned anything else. We tested an 830 Baker vs a custom Quickfuel 950 and the 950 made 5 hp more. Both very good carbs. The oval track carbs also had the secondaries coming in at the same time. My Buick liked that a lot. Throttle response was really quick. Will be very interested in a dyno comparison.
I found someone local (friend of a friend) that specializes in old school tuning, years of Holley experience. I scheduled a dyno day, at the shop he works at, for next Friday. Here's the plan; get a baseline on the 950 first, then tune/optimize it as best we can, then install the old 850 with known setup to get a baseline then do some minor tuning on it. I'm hoping to back this up with ABA testing so I'll re-install the 950 with the initial setup to make sure we can repeat. I have a complete set of jets and the shop has a wide selection of air bleeds (idle, high speed, emulsion). We'll also be using a wideband O2 to see what the fuel curve looks like and make adjustments as needed to flatten it out. My corrected average times so far... w/850: drag strip trip 1 - 1.750s 60', 11.595 @ 115.21 (calm) drag strip trip 2 - 1.745s 60', 11.545 @ 117.5 (~5 mph tailwind) w/950: drag strip trip 3 - 1.795s 60', 11.67 @116.23 (~10 mph headwind) This will be my first time for my car on the chassis dyno.....suggestions welcomed :TU:
Hey Doug, Are u ready for the Marshal rd Nationals?:beers2: I'm gettin ready to put on my 950hp, when I last ran it, it would not idle at all but made an extra 12hp over my 850. It has 75 jets all around, sounds like that's way too small. pv is a 3.5 I have about 7in vac @ idle in neutral. What would you guys do for a starting point? I plan on goin for a dyno tune & gettin it dialed in soon, but want to get close before I take it. I am making 500+hp with the 850.
Rick, Spring must be here to hear from you. :grin: My 950 idles great. If you want to we should try and get together and let you try mine. I never thought that there was much in the way of HP difference between the 850 and 950 but the four corner idle circuit should make the idle much better. Also the newer carbs have more places to make adjustments. Let me know what you want to do. As for the Nationals :laugh: I hope that I will have something new under the hood. Working on putting a Procharger on. Details are just killer for this. New fuel system, upgrade ignition with boost referenced retard, who knows what on the jetting. Also adding Postons girdled oil pan. I should be pushing over 600hp with 5 psi. Just want to get it working with the lowest boost possible this year. Pulling the dash apart right now to add some new instruments. You should be running 80's all around if you use a secondary power valve. If you do not run a power valve in the secondaries run 88's there. That will get you into the ball park. Need to get an O2 meter on that thing. One of the new instruments I am putting in is a wide band meter. Mounted right where the clock should be. Also adding a fuel pressure gauge and boost gauge.
Night before last I was peering down the 950HP to check throttle adjustment and found the throttle blades were not fully opened at WOT (my throttle bracket is not the best setup) :error: . I'm guessing the secondary blades were only about 75 deg. I've got plenty of time to check everything before "dyno Friday...since I got laid-off today :spank: Nice 33 week severence package however, plenty of time to shoot for double pay with a new job. :dollar:
Had a nice day at the chassis dyno! I am proud of the old 455... it ran smooth and we tuned in a little more RWHP. At the engine dyno, back in Feb. this year, this 455 made 525 HP and 550 TQ. I've raced at the strip three times now, running anywhere from 11.4's to 11.8's @ 115 to 119 mph. Now with the 950HP installed, I needed to get it tuned for the BBB (purchased from a Chevy 454 guy). We made 24 runs total today, slowly climbing up the HP/TQ ladder, baby steps you might say. I was hoping/estimating for at least 400 HP at the wheels. First Run: 421.06 TQ and 417.91 HP Jets: 80 front and 81 rear, 5.5 PV's Shooters 35/35 Idle feeds: .035/.035 Main (high speed) bleeds: .033's Idle Bleeds: .070's Emulsion bleeds all four .028" (rear) 32 deg. total timing, all in by ~2300 A/F getting more fat at the upper rpm's.....12.15 in the 5200 to 5700 range 420 HP is 80% of 525 (typical loss with automatic and decent converter) Last Run: 431.80 TQ and 432.27 HP Jets: 78 front and 81 rear, 5.5 PV's Shooters 35/35 Idle feeds: .035/.035 Main (high speed) bleeds: .038's, to lean upper rpm range Idle Bleeds: .070's Emulsion Bleeds all four .031" (rear), to lean upper rpm range 32 deg. total timing, all in by ~2300 A/F: 12.7 in the 5200 to 5700 range, ~14.7 cruise at 55 or 2100 rpm We only ran the 950, and did not put the 850 on, like I had planned. Only down side, on the way home I ran over what looked like a lug nut. Did not think anything of it... until I stopped for gas and heard a "Psssst" from the rear drivers side tire! I had the TA Drag radials almost to a slick too, when they hook best. I got home in time before it got too bad . Time for some Mickey Thompson rubber I guess o No: Next drag strip trip should show something, with the added 14 RWHP and new drag radials. Might help my ~slow 1.75 60' times?
Well, I put 80 jets all around & installed the 950 hp, it runs pretty good, but don't want to idle in gear. Took a 300 mi road trip & it cruised great. I'm putting in an 02 bung tomorrow night & have a dyno appointment Sat morning to fine tune that bad boy!
This still kind of pertains to this thread. I have changed me mains by 2 sizes down, at idle it still seems rich at least it still smells pretty strong. After changing jets do the idle screw have to be reset and also what about float level? This Holley thing is really new to me. Thanks Rick
I went to A&A (1 mi from my place) we were real limited on time, so just did a few pulls. 78's in front, 85's & no pv in back. 386 hp 476 torque. New Flowmasters just got here! Gotta go put em on now!!
It would be fun to line em up one day, but I think you might hurt me with my 3.08 gear & street tires I dont expect much more then a 12.50, but this winter I do want to get an OD trans & a better gear.
Not sure about that. Buicks can handle that gear. I should take you to the 1/8 th but your 50 exta HP are going to tell on the top. I may be going to Lapeer this Sat. Have a Pontiac club race.
Rick, Changing main jets will not affect idle mixture. This website will get your started with some Holley tuning info. http://www.bob2000.com/carb.htm
Some new info. I tried going to 83's for the air idle bleed. Did not help with the number of turns out on the idle adjustment screws. It still wants about 1/2 turn out on each (4 corner) and made it much more sensitive to adjustment. Going back to the 73's. Too bad that did not help sure is easy to change. I guess the next step is to try smaller idle feeds. Right now I am at .035 idle feeds. Thinking about going to .030, any suggestions. Also what is needed for the air bleeds with this idle feed. Good news on the jets, Jegs will sell pairs of these. They are Quickfuel not Holley. WOT is looking good though, a run through the gears shows 12.5 AFR the whole rev range.
When my mixture screws in the back only wanted 1/2 turn out I adjusted the throttle stop to open the butterflies a little more (drilling them would work too). Now my idle mixture screws in the rear are about 1.2 turns out. My motor liked AFR in the 12.8 range for WOT power. I'm at 14.7 or so at light cruise.
All my mixture screws are at 1/2 turn out. I am going to take the carb off and check how much the butterflys are open. I do know that when I adjusted in the past for the square transfer slot that my idle was way to high. As far as AFR at WOT it is really an estimate. Trying to watch the guage, tach and road at the same time is a little harry :laugh: It did remain in the 12's all the time. Need to get the vacuum boost guage hooked up so I can see when the power valve is coming in.
Strap in your video camera to do the recording of the gauges..... that's what I do. You will have a time stamp and you can narrate as needed. Use Movie Maker on your PC to view and edit.
I just stumbled across this thread. There's some good info here :TU: I've had a terrible time with my QF850 (annular). I have it jetted down to 72 primary 78 secondary. It still runs rich but my drop base air cleaner is really restrictive. At the track, I run it with the air cleaner off and it runs really good and clean. I did notice some slight popping at the high end of second gear as I approached the traps (1/8 mile track). My shop guy says it may be leaning out. I like the one suggestion to jet up until the mph falls off. I'm also contemplating getting a different air cleaner for normal cruising. I'm also having issues getting the MT's to hook when I load the converter. How much of a pain is it to install an AFR? Do you bung the headers or farther back? Thanks for any input
