"Big" 4150-type carbs w/ annular boosters
#179514
12/31/08 11:41 AM
12/31/08 11:41 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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Anyone had good luck running "big" (1.56+ venturi) 4150-type carbs w/ annular boosters? One of the changes I made to my Gold Claw towards the end of the year was to switch from 1.42" venturi w/ downleg boosters to 1.56" venturi w/ annulars. I was expecting to see some MPH improvement, but the results were about a .02 improvement in 60-ft. time and no improvement in MPH with better atmospheric conditions. It also runs fatter down low and seems to transition onto the main ciruits too quickly on the street, even after some float level & jetting changes. It sounds like my results aren't that untypical, based on some carb discussions I've had offline w/ a couple of knowledgeable people. However, it does leave me wondering if I should bother trying the 1.59" venturi w/ the annulars, or go back to the 1.42" / downleg combination. The latter definitely ran cleaner on the street, even though I didn't have the idle quite sorted out at the time. It may be that I have to give up some 60-ft. on the track to get the car to run better on the street. I've also been told I should get a wide-band O2 sensor, but Santa must have forgotten to put that in his bag this year.
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: AndyF]
#179516
12/31/08 12:42 PM
12/31/08 12:42 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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I think annulars would help atomize fuel better. it seems like your car liked the change to a bigger venturi but the slow speed thru it is causing fuel to drop out of the downleg.
can you switch boosters easily? OriginalRT has a booster tool
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: BradH]
#179517
12/31/08 01:14 PM
12/31/08 01:14 PM
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Joined: Aug 2003
Posts: 43,007 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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My experience with 4150 carbs. with annular boosters is the higher you rev the motor the fatter the AFR gets Changing the jets doens't fix it either, both of the carbs shop in SO CA that I talk to said to switch them(830 CFM 4150 carbs) to downlegs so I did. I do have two 1000hp 4150 with annular boosters off a tunnel ram set up that I bought and haven't used yet, I did loan one out to a fellow bracket racer that runs a 440 in a Duster, he made one run and took it off because it didn't have jet extensions in the rear and bog a little bit off of the line I had a set of extensions in the trailer but he didn't want to try it again, he said that it ran good in the pits, idle clean and ran good after the bog went away but it did slow down the 60 fts and the 1/4 ET but it may have ran a little bit more mph, but I can't really remember the exact details. I will try them on the tunnel ram soon with the wide ban on the car and on the engine dyno when I dyno it.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: Cab_Burge]
#179518
12/31/08 01:34 PM
12/31/08 01:34 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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i tried an annular 2 months ago and couldnt get it fat enough was plenty fat at idle and cruise though
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: sixpackgut]
#179521
12/31/08 04:51 PM
12/31/08 04:51 PM
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Joined: Aug 2003
Posts: 43,007 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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Not trying to hijack this thread, usually when you cannot get the carb. rich enough to slow the car down on the top end it is usually a fuel supply problem which can be caused by many things like you already alluded to, to small of size of needle and seat, to small of a pump, line size from the pump, to small of a filter, to small pick up size in the tank and so on, the list is almost endless I had this problem last year with a Magnafuel 275 pump, I couldn't slow the car down or show a enrichment on the wide ban by jetting up, I replaced the 275 with a Magnafuel 300 pump and immediatly slow the car down with the same jetting as with the 275 when I jetted the carbs up and the wide ban changed from 14.2 on the line to 15.1 during the run with the old pump to 12.2 during the complete run with the new pump
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: BradH]
#179526
06/18/09 06:43 PM
06/18/09 06:43 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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ever try the downlegs with the current sleeve?
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: sixpackgut]
#179527
06/18/09 07:23 PM
06/18/09 07:23 PM
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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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Quote:
ever try the downlegs with the current sleeve?
Naaaaahhhh... you have to run in the 9's for that combination to work.
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: AndyF]
#179531
06/19/09 09:11 AM
06/19/09 09:11 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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Haven't seen the article, IIRC. I've let all my magazine subscriptions expire and don't see this stuff on a regular basis. EDIT - I'm assuming you mean this article . "In theory..." I'd think the 1.59" venturi w/ annular boosters would be the best all-around setup. The problem is that moving from theory to reality could take a lot more time getting it dialed in than I probably have to mess with it.
Last edited by BradH; 06/19/09 09:43 AM.
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Re: "Big" 4150-type carbs w/ annular boosters
[Re: AndyF]
#179533
06/19/09 10:32 AM
06/19/09 10:32 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Yep, that is the article. The picked up almost 100 ft-lbs of torque with the annular boosters at one point in the torque curve. I've seen other dyno tests with similiar results. I've never figured it out exactly but the big cam + single plane intakes combinations seem to be the most likely to pick up big with the annular boosters.
That doesn't mean it will be any faster at the track though because the point where the torque increase is made usually doesn't come into play.
i think Andy is right about this. what i've personally seen is the annular carbs work best on shorter stroke combos that have less signal to the carb, or any combo that has just a bit tooo much plenum area/port cross section.
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