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11-30-2009, 09:26 PM
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#1 |
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Registered User
Join Date: Apr 2008
Location: Imperial Beach, CA
Posts: 1,040
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What helps RPM's?
I am looking at changing my valve springs,cam in hopes of getting a 7-7500 rpm reliable engine. Do i need a lighter Crank,rods,piston or is it mainly the cam and springs. I do know all help but can you pick up more RPM's from cam and springs or by the balancing?
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69 c-10 BBC  462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles.  3.5/6in drop. My Build.
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11-30-2009, 10:18 PM
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#2 |
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Registered User
Join Date: Dec 2006
Location: Trinidad, Colorado
Posts: 642
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Re: What helps RPM's?
Bottom end in your sig should be fine upwards of 8K RPM. I would recommend Isky red zones with a solid roller cam, and aluminum roller rockers. Of course you need high flowing heads to hit 8K.
Gearing will get you there also, but may slow you down at the same time...LOL Check out this site for BBC advice! http://www.chevelles.com/forums/forumdisplay.php?f=13 A.........
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69' 3/4 4X4 470ci BBC 700 HP....  D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959 |
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12-01-2009, 09:48 PM
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#3 | |
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Registered User
Join Date: Nov 2007
Location: Bay Area, Ca
Posts: 2,841
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Re: What helps RPM's?
Quote:
Gearing will not "change" operating RPM of a motor. Operating RPM is typically a function of cam timing. There are other things that can hold RPM back like intake manifolds and headers that are not appropriate for a given combo. But in all reality it is a combo, and needs to be thought of that way. Generally speaking and cam with a later intake valve closing point and more overlap will spin more rpm. To Marv's point, piston speed can wear on bottom end parts very quickly. The heavier the components the lower you want to keep piston speed.
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------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49 |
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12-02-2009, 08:18 PM
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#4 | |
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Registered User
Join Date: May 2002
Location: NJ
Posts: 910
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Re: What helps RPM's?
Quote:
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83 C10 Stepside (SOLD, it was a blast!) 383 MASS-FLO EFI/TKO II 600/3.90 Posi 10 bolt S475 and C4 DM running, fine tuning turbo=  Douchebag Racing: Runs Fine all the Time |
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12-01-2009, 08:57 PM
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#5 |
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Registered Truck Offender
Join Date: May 2008
Location: hells training ground (aka Ariz)
Posts: 3,118
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Re: What helps RPM's?
462" takes a lot of piston swinging around, and a lot of stroke. It's the crank forcing all that heavy weight to change directions that typically rips a rod cap off or piston pins out of a piston. I'd be cautious on the top end when you snap the throttle closed.
Myself I'm not a fan of the KB piston line. Do you know what they weigh? As a comparison a typical JE BBC 460 flat top is in the 550 - 590gram range. Whatever you do, when freshening the motor take special note of the piston pin bores.
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Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral. |
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12-02-2009, 08:19 PM
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#6 | |
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Registered User
Join Date: May 2002
Location: NJ
Posts: 910
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Re: What helps RPM's?
Quote:
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83 C10 Stepside (SOLD, it was a blast!) 383 MASS-FLO EFI/TKO II 600/3.90 Posi 10 bolt S475 and C4 DM running, fine tuning turbo= Douchebag Racing: Runs Fine all the Time |
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12-02-2009, 08:32 PM
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#7 |
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Registered User
Join Date: Apr 2008
Location: Imperial Beach, CA
Posts: 1,040
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Re: What helps RPM's?
I would like a 7-7,500 rpm limit for when i want to. I would not be at it all the time i just want an engine that can hit it.
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69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles. 3.5/6in drop. My Build.
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12-02-2009, 09:07 PM
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#8 |
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Senior Member
Join Date: Apr 2000
Location: Delta,Pa
Posts: 14,948
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Re: What helps RPM's?
stuff will live a lot longer at 6500rpm than it will at 7500 especially in a big block. you base your gearing on your engines operating rpm. unless your drag racing only theres no need to spin 7500rpm unless you want to spend a lot of money trying to find a combo that doesnt fly apart and constantly break stuff.
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Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member. |
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12-03-2009, 09:30 AM
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#9 | |
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Registered User
 
Join Date: Jul 2007
Location: Ottawa Ontario Canada
Posts: 1,156
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Re: What helps RPM's?
Quote:
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12-09-2009, 07:01 PM
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#10 |
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Registered User
Join Date: Dec 2006
Location: Trinidad, Colorado
Posts: 642
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Re: What helps RPM's?
Correct me if I'm wrong.....But...
If you have an engine built to make peak power at 7500RPM, but your gears are in the "high way" range, say under 3.00 : 1...Then why wouldn't you get lower gears to put the engine into its power band? A........
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69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959 |
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12-09-2009, 09:01 PM
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#11 |
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Registered User
Join Date: Apr 2008
Location: Imperial Beach, CA
Posts: 1,040
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Re: What helps RPM's?
I have 3.70:1 rear gears. I will be able to hit 6500 easy just would like to go a bit higher when i want. The rpm power is very nice i was just looking at how i could add a few revs.
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69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles. 3.5/6in drop. My Build.
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12-09-2009, 09:59 PM
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#12 | |
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Registered User
Join Date: May 2002
Location: NJ
Posts: 910
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Re: What helps RPM's?
Quote:
You select the gearing based on what your power band is, transmission, tire size you have and what your goals are. If I want an 1/8 mile car/truck and the power band is 4500 to 7k rpms then I could go with a really steep gear 5.XX:1. When I am going through the traps I want my engine to be at 7k+ rpms. Now if I want a 1/4 mile car/truck with the same engine/transmission/tire then I certainly can't run the same gear. I would need a lower gear. Either way the gear isn't going to affect what my power band is or how high my engine revs.
__________________
83 C10 Stepside (SOLD, it was a blast!) 383 MASS-FLO EFI/TKO II 600/3.90 Posi 10 bolt S475 and C4 DM running, fine tuning turbo= Douchebag Racing: Runs Fine all the Time |
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12-09-2009, 11:25 PM
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#13 |
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Registered User
Join Date: Nov 2007
Location: Bay Area, Ca
Posts: 2,841
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Re: What helps RPM's?
Diesel,
The premise of changing the gear based on the racing your are doing, is correct. IE the example above 1/8 might need a 5.30 gear. Same car 1/4 might need a 4.11. Same car, standing mile, you might need a 3.42 in that car. The idea of tailoring your gear ratio to the style racing you are doing is correct. But, if a motor can only spin say 6k rpm, going from a 2.xx gear to a 4.xx gear, your motor is still only going to spin to 6k rpm..
__________________
------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49 |
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12-10-2009, 10:32 PM
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#14 |
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Registered User
Join Date: Dec 2006
Location: Trinidad, Colorado
Posts: 642
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Re: What helps RPM's?
Super73....
That was a great explanation of what you are all trying to say! Things are a bit different with a sled hooked to you...LOL I understand exactly what you guys meant. A.........
__________________
69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959 |
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12-11-2009, 10:19 AM
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#15 |
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Registered User
Join Date: Jul 2009
Location: Florence,Mississippi
Posts: 301
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Re: What helps RPM's?
JUST GRAB THE SECOND STAGE AND YOU WILL SEE AL THE RPM'S U WANT
 GREAT INFO GUYS THIS IS THE MOST HELPFUL PEOPLE IN THE INTERNET WORLD. KEEP UP THE GOOD WORK.
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first track pass with the new motor on motor http://youtu.be/YgrJaEF_TaQ Last edited by bigboybodry; 12-11-2009 at 10:22 AM. Reason: PIC |
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12-11-2009, 11:14 AM
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#16 |
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Registered User
Join Date: Apr 2008
Location: Imperial Beach, CA
Posts: 1,040
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Re: What helps RPM's?
I think ill stick with a 200 shot for a while. Never had juice and dont want to run wild with 2 stages right off the bat.. HAHA. Great looking set up you have there Bigboy.
__________________
69 c-10 BBC 462ci, forged crank, H-beam rods, 10.5-1 KB forged pistons, Dart Iron Eagle 308cc, Straub Cam, Comp Cams chrome moly full rollers, Weiand Team G, Prosystems 950, TH400/3500 Dalenzie stall, Currie 9+ Detroit Locker w/31spline axles. 3.5/6in drop. My Build.
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12-11-2009, 02:05 PM
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#17 | |
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Registered User
Join Date: Jul 2009
Location: Florence,Mississippi
Posts: 301
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Re: What helps RPM's?
Quote:
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first track pass with the new motor on motor http://youtu.be/YgrJaEF_TaQ Last edited by bigboybodry; 12-11-2009 at 02:54 PM. Reason: added from nos down. |
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12-11-2009, 01:36 PM
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#18 | |
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motor exploder
Join Date: Mar 2009
Location: Pittsburgh, PA
Posts: 2,346
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Re: What helps RPM's?
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dayum!!!!
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Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac  Use the SEARCH function on this forum - it is your friend!! |
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