Author
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Topic: Buying a carburator ?
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66bluefb Gearhead Posts: 467 From: Okla.City,Okla. Registered: May 2002
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posted 12-25-2002 10:57 AM
I am thinking about buying a holley carb. for my 302. Almost everyone says it is the best, better than my carter 625. What kind should I buy? Is a 750 too big for my set up? Could I buy a rebuilt one some place and save some cash?Thanks,Tony------------------ http://ourworld.cs.com/blagintony/myhomepage/auto.html 86-302 HO bored .030 over crank .010 under B-303 cam ,harland sharp roller rockers performer rpm intake, 625 carter 66-289 heads, ported with 160-194 valves, 3 angle valve job 4 speed toploader pony seats [This message has been edited by 66bluefb (edited 12-25-2002).]
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Moneymaker Administrator Posts: 19964 From: Lyons, IL, USA Registered: May 99
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posted 12-25-2002 12:36 PM
670 cfm Avenger #0-80670 Holley should do just fine. ------------------ Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver MCA member# 53321 NHRA and IHRA SS/LA National Record Holder '00, '01, & '02 Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 Professional Manwhore The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked." Quote #2: "Make sure brain is in gear before engaging mouth!" Quote #3: "If you can't run with the big dogs, stay on the porch!" www.moneymakerracing.com
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Toronado3800 Gearhead Posts: 364 From: St. Louis, MO Registered: Jul 2001
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posted 12-25-2002 05:59 PM
I copied the below chart from the Holley Web site I was looking for a formula I saw before which was somthing like (max rpm * 5432 / cubic inches.) but I can't find it. ****************** Vacuum Secondary Carb Chart Vacuum secondary carbs are typically used in street applications where performance and economy are important considerations or in race applications where a car has limited traction and needs a "hit" that can be tailored to the traction available. ENGINE SIZE MILD HOT WILD 300 390 600 650 350 600 650 750 400 650 750 750 450 750 750 850 500 750 850 950 550 850 950 950 Double Pumper Carb Chart Double Pumper carbs are typically used in any application where maximum performance is required and economy is less important. Double pumpers have progressive mechanical secondaries and are ideal for the hard core enthusiast.
ENGINE SIZE MILD HOT WILD 300 N/A 600 650 350 600 650 750 400 650 750 800 450 750 800 850 500 750 850 950 550 850 950 1000
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Red65 Journeyman Posts: 87 From: Northglenn, CO, USA Registered: Jul 2002
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posted 12-25-2002 08:22 PM
I think you're looking for this formula:RPM X Displacement / 3456 * VE VE = Volumetric Efficiency (use .85 for a good street engine) Source: Martin, Isaac. FORD WINDSOR SMALL BLOCK PERFORMANCE, HP Books: New York, 1999. page 78.
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Pierre Gearhead Posts: 394 From: Near Paris, France Registered: Apr 2002
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posted 12-26-2002 10:06 AM
I looked extensively into this situation with a 302 middly built-up. Holley made a HUGE difference over my previous Edelbrock 600 in regard to throttle response, mpg was similar when driving nice.After extensive testing between the 750 vac sec and 600 Double pumper, I got the same power out of both (that I could "feel" or time) the 750 cured a lean condition but increased mpg drastically so I went back and finally settled for a new 600 DP sligtly richer than stock. I am just an average guy with limited mechanical knowledge, and this is just my 2 euros
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Red65 Journeyman Posts: 87 From: Northglenn, CO, USA Registered: Jul 2002
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posted 12-26-2002 11:06 AM
Pierre,Saw this Boss 302 in Paris last year, about a about 1000 meters from the Arc de Triomphe. Just thought you might find it interesting, I sure did!!
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Red65 Journeyman Posts: 87 From: Northglenn, CO, USA Registered: Jul 2002
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posted 12-26-2002 11:11 AM
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Pierre Gearhead Posts: 394 From: Near Paris, France Registered: Apr 2002
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posted 12-26-2002 01:08 PM
quote: Originally posted by Red65: Pierre,Saw this Boss 302 in Paris last year, about a about 1000 meters from the Arc de Triomphe. Just thought you might find it interesting, I sure did!! [IMG] http://us.f1.yahoofs.com/users/51894e89/bc/Yahoo!+Photo+Album/Image-03.jpg?bcukyC.Ariql8G6H[/IMG]
I am not seing the picture. Not sure if it is my computer !! Email it to me please There are an estimated 4000 mustangs that where sold here, 1500 still running, some very irregularly. Concidering all of the taxes & duties & maintenance costs, these cars were (back then) fairly expensive by the time they got here so only the well-off people were able to afford them. So most of them are loaded with options and there are some pretty rare models. Switzerland is a real Gold mine for all kinds of Shelby and rare stuff. I would be interested to see that Boss though
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Red65 Journeyman Posts: 87 From: Northglenn, CO, USA Registered: Jul 2002
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posted 12-26-2002 01:47 PM
Pierre,You've got mail!! By the way, it was more like 300 meters, not 1000 meters (1 km).
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Jeff Gearhead Posts: 280 From: Moore, OK USA Registered: Mar 2001
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posted 12-26-2002 02:25 PM
The formula for your 302 quickly reduces to:cfm=1/10 rpm Thus for 6000 rpm, cfm = 600 cfm for 7000 rpm, cfm = 700 cfm for 8000 rpm, cfm = 800 cfm Look at your intake specification. If the power bandwidth for the intake is 1500-6500 rpm, then using 6500 rpm as the upper bandwidth rpm then: for 6500 rpm, cfm = 650 cfm. I think the safe bet for you is the Holley 670 street avenger previously mentioned. This carb must be sitting on a Edelbrock Performer or Weiand Stealth manifold to reach its potential. If you want more low end torque and smoother throttle response go with the 570 cfm street avenger. If you're not sold on Holley carbs, use the same cfm range in an Edelbrock or Carter.
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Toronado3800 Gearhead Posts: 364 From: St. Louis, MO Registered: Jul 2001
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posted 12-26-2002 05:25 PM
Thanks for the formula RED! That is what I was looking for.
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