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Re: All the specs to start your dyno #s guesses! 8^)
[Re: fast68plymouth]
#2391540
10/22/17 11:56 PM
10/22/17 11:56 PM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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The part-throttle was rich on all of them, not lean, and really out of normal range in at least one case. And not just a little rich either........some were way way rich with light loads simulating highway driving. Under those conditions, the main circuit is already flowing plenty of fuel,........and you're not going to lean out the mixture by 3.5 points by tweaking an air bleed. All the carbs had a tendency to richen up throughout the run(both the turbines and O2 agreed).......some worse than others. - Enough of the carb stuff I saw didn't make sense to me that I ended up stealing Quick Fuel's tune (as much as I knew, at least) for the 1.59 v annular rather than use what I'd intended And, as I recall, it seemed to have the flattest fuel curve. Do you think if you had the time to sort it out, you could have made some emulsion changes to clean up the middle?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391556
10/23/17 12:31 AM
10/23/17 12:31 AM
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Joined: Jan 2003
Posts: 14,492
So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,492
So. Burlington, Vt.
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Keep in mind the wot a/f ratios were fairly decent on both the QFT carbs when they made their best runs.
So, whatever you do to lean out the part throttle cruise, you're trying to do something that changes that part of the carbs operation by around 3 points......and have essentially zero affect on wot operation.
There are smarter guys with carbs than me, but I have a feeling it's easier said than done.
The QFT 1.52 carb had the least offensive part throttle cruise operation when it was first bolted on.......low/mid-12's, with the 80/90 jets.
However, with that set up, the motor didn't take a load real well, and I aborted the run about 800rpm into it when I saw the a/f ratios weren't getting out of the 15's.
Once the jetting was increased to get the wot a/f ratios in line, and the power up......which ended up being 88/98....... then the part throttle cruise was down at the bottom of the 11's.
The Demon had the next best part throttle operation, low-12's, and had the best throttle response.
IMO, this carb is probably the best candidate of what we ran to be tweaked to get decent part throttle operation for street use.
The down side of this carb as we ran it was, it had the biggest change in wot a/f operation from the bottom of the run to the top........it really richened up at the top end.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: davenc]
#2391591
10/23/17 02:08 AM
10/23/17 02:08 AM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
OP
Taking time off to work on my car
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OP
Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Brad,
Thanks for sharing your results. How much HP did you gain with each 2* of timing? Did you only test the baseline carb at 34* timing? I wondering how close the baseline carb would have been with 38* timing and the 1" spacer, and whether your original carb is the best solution for a street car? Re timing... - One comparison between 34 and 38 using the same carb & spacer picked up 15 HP and almost 8 lbs-feet at their respective peaks. - Going from 34 to 36 on a different carb & spacer combination picked up 13+ HP, but only about 1.5 lbs-feet; from 36 to 38 didn't pick up any HP (actually lost 2 at peak), but the engine got into the 670s 100 RPM sooner & stayed above 670 for 100 RPM later, and picked up 3.5 lbs-feet. - No, never tried the Race Demon with the Super Sucker and more ignition advance. I'll need to spend more time on it when the car is running again to see what it does.
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: fast68plymouth]
#2391647
10/23/17 09:58 AM
10/23/17 09:58 AM
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Joined: Feb 2005
Posts: 4,310
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,310
Prospect, PA
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The part-throttle was rich on all of them, not lean, and really out of normal range in at least one case. And not just a little rich either........some were way way rich with light loads simulating highway driving. Under those conditions, the main circuit is already flowing plenty of fuel,........and you're not going to lean out the mixture by 3.5 points by tweaking an air bleed. All the carbs had a tendency to richen up throughout the run(both the turbines and O2 agreed).......some worse than others. - Enough of the carb stuff I saw didn't make sense to me that I ended up stealing Quick Fuel's tune (as much as I knew, at least) for the 1.59 v annular rather than use what I'd intended And, as I recall, it seemed to have the flattest fuel curve. Thanks BH/DP for posting. This (WOT fuel curve, cruise) mirrors my past results. Did you look at the boosters at cruise RPM and the A/R befor the booster started flowing? Mine was fat before they were flowing and not flowing much at the lower RPM. The IFR did matter. My testing was in the 2000 to 2500 range. Do you believe that if you did track testing under similar conditions, and based on et and mph, you would have come up with the same hierarchy? Do you believe that cruise numbers in the 12s will truly cruise poorly on the street. Finally,based on what an O2 sensor is really measuring, and how low the fuel flow/air flow measurements are (relative to their span) how robust do you thing the cruise A/F numbers are? Thanks
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391665
10/23/17 10:41 AM
10/23/17 10:41 AM
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Joined: Feb 2008
Posts: 714
Central TEXAS!!!!
sr4440
super stock
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super stock
Joined: Feb 2008
Posts: 714
Central TEXAS!!!!
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Since this is a street car, were you running a PCV valve? Then tend to lean out the low to mid-range without having much affect up top.
Joe
Without Data, you’re just another guy with an opinion.
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391735
10/23/17 12:32 PM
10/23/17 12:32 PM
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Joined: Jan 2003
Posts: 14,492
So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,492
So. Burlington, Vt.
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Russ, on the carbs where the part throttle cruise was in the low 12's, the motor was running smoothly enough where I don't think it would drive bad at all.
I've had quite a few years and plenty of examples to look at, and when they come off the dyno like this, and get put right into the car without getting the part throttle a/f ratios into a more favorable range....... The trend does seem to suggest that the instrumentation isn't lying.
Those motors end up getting abnormally poor fuel mileage, plugs that are always dark, and sometimes even gassy smelling oil.
I had a really mild 505 on the dyno about a week ago.
It had a Holley 850vs on it.
Jets 80/88, part throttle operation very crisp and clean in the low-14's, WOT in the 12's & 13's.
No tendancy to get "fat" at any throttle or load setting.
That carb was a good match for that motor.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391751
10/23/17 12:58 PM
10/23/17 12:58 PM
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Joined: Jan 2003
Posts: 17,840
S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,840
S.E. Michigan
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Good reading. Thanks for sharing your work!
I actually came here wanting to talk about carbs a bit, but after reading this, it seems it might be a bad time to ask questions
Last edited by ZIPPY; 10/23/17 12:58 PM. Reason: really bad typing
Rich H.
Esse Quam Videri
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391765
10/23/17 01:20 PM
10/23/17 01:20 PM
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Joined: May 2004
Posts: 3,210
robin hood country
deaks
master
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master
Joined: May 2004
Posts: 3,210
robin hood country
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I would be very pleased with those hp figures on a stock stroke motor with that comp, that would put my 3200# car solidly into the 9's The timing aspect suprised me as well.
Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200#
best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft
best 60ft 1.36
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: fast68plymouth]
#2391797
10/23/17 02:10 PM
10/23/17 02:10 PM
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Joined: Jul 2004
Posts: 19,317
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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I'm sure that would help with the part throttle. Did you guys mess w/the emulsion cos you can change the mixture quite easily in the range needed buy the location and sizes.........
Last edited by Thumperdart; 10/23/17 02:14 PM.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: Thumperdart]
#2391823
10/23/17 02:58 PM
10/23/17 02:58 PM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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I'm sure that would help with the part throttle. Did you guys mess w/the emulsion cos you can change the mixture quite easily in the range needed buy the location and sizes......... That's what I was getting at. My thinking was adding some bleed in a middle hole, or if there was already a bleed there, open it up a bit. Am I thinking on the correct lines?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391841
10/23/17 03:10 PM
10/23/17 03:10 PM
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Joined: Jan 2003
Posts: 9,985
Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,985
Frostbitefalls MN (Rocky&Bullw...
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Congrats on a great build Brad. It will "haul the mail" as they would say back in the day  What will your car weigh when ready? We have a little time for "guess your ET" !
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: madscientist]
#2391858
10/23/17 03:27 PM
10/23/17 03:27 PM
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Joined: Jul 2004
Posts: 19,317
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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I'm sure that would help with the part throttle. Did you guys mess w/the emulsion cos you can change the mixture quite easily in the range needed buy the location and sizes......... That's what I was getting at. My thinking was adding some bleed in a middle hole, or if there was already a bleed there, open it up a bit. Am I thinking on the correct lines? Exactly what I've done on the street w/interesting results and yes, adding bigger or smaller not necessarily more changes things pretty quickly and so do the hi-speed bleeds............The richness imo has a LOT to do w/a healthy bigish motor sucking through small venturi's/boosters makin em go rich and I see it all the time on my car and if they put a real carb on that beast(1050 dommy of course) that will change guaranteed.......... 
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391861
10/23/17 03:30 PM
10/23/17 03:30 PM
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Joined: Jan 2003
Posts: 13,354
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,354
Marion, South Carolina [><]
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Nice job! HP is about where I expected it to be. Makes more torque than I thought it would though.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: All the specs to start your dyno #s guesses! 8^)
[Re: BradH]
#2391870
10/23/17 03:49 PM
10/23/17 03:49 PM
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Joined: Jan 2003
Posts: 2,094
central texas
krautrock
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,094
central texas
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Went back to look at the list of carbs. Did 6A make it on the motor? Figure that carb might've had a little calmer emulsion than some of the others.
1. BG Race Demon RS set up w/ 1.42" venturi sleeves
=> previous tune as used on my car when it ran 10.5s as driven to the track
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So... that means you can pick two (2) of the remaining carbs listed.
2. BG Gold Claw set up w/ 1.50" venturi sleeves
=> new & untested config
=> pushing the limit for venturi size w/ downleg boosters that I believe will work well on my car
3. QFT/Proform 1.45" venturi main body used as basis for complete carb
=> original boosters; new & untested
=> Basically a Proform "950" with a better tune
4. QFT/Proform 1.52" venturi main body used as basis for complete carb
=> BLP modified boosters; new & untested; this is the limit for venturi size w/ downleg boosters I'll try
=> comparable to a QFT Race-Q 1000, which Quick Fuel used to win the small-block class in the last BLP Carb Challenge held a few years ago
5. QFT/Proform 1.59" venturi annular booster main body used as basis for complete carb
=> original boosters; new & untested
=> comparable to a QFT Race-Q 1050-AN, which AndyF said has been the best performing 4150 carb he's tested so far
6a. Holley Ultra HP/XP 1.60" venturi carb re-fitted with Mark Whitener's custom annular boosters
=> purchased from AndyF 'cuz I thought it looked "interesting"
=> Dominic "Thumper Carbs" worked on the tune to make it more driveable vs its original dyno tune
6b. Same as #6a, only with Holley Ultra HP/XP 1.56" venturi main body blended out to 1.58" and equipped with the same 12-hole annular boosters as the #5 carb
=> new & untested config
=> Mark Whitener's flow testing of a variety of carbs showed the modified Ultra HP/XP 1.56" (1.58") venturi main body flowed noticeably better than Holley's 1.60" venturi body... so I decided to build one
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