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#1 |
Registered User
Join Date: Jan 2009
Location: colorado springs
Posts: 479
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edelbrock tunning tip
tried this out today and it worked good so I thought I would pass it on.
start the motor and let it warm up, at idle speed and warm loosen the screw that holds the rod and spring door shut, the idle vacum should hold the door, shut if it doesnt you already know your spring is to strong. From there use a magnet to pull the door up giving you a view of the rod and piston, then you can use different throttle positions and watch the response. Ive also thought about cutting out a little piece of plastic to fit and screw it down so I can watch and tune. Hope this helps someone |
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#2 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: edelbrock tunning tip
That sounds like a good idea. You could use a vacuum gauge to find what vacuum releases it.
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#3 |
Between Trucks...
Join Date: Mar 2002
Location: Los Angeles, CA.
Posts: 3,830
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Re: edelbrock tunning tip
That's a pretty cool idea. Thanks.
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#4 |
Redefining LowBudget
Join Date: Mar 2009
Location: lebanon Cow Hampshire
Posts: 4,538
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Re: edelbrock tunning tip
![]() great tip but I have no clue what your talking about
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1970 C10 CST fleetside 472 ....big dreams little cash... SunShine Syndicate.. ![]() Mikes Sandwich Fair Run OCT 8th 2011
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#5 |
Registered User
Join Date: Jan 2009
Location: colorado springs
Posts: 479
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Re: edelbrock tunning tip
Ya , I use a vacum gauge also , but watching it work is kind of cool and informative,
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#6 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: edelbrock tunning tip
no idea what your talking about but sounds like ya know what your doin! lol
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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#7 | |
Redefining LowBudget
Join Date: Mar 2009
Location: lebanon Cow Hampshire
Posts: 4,538
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Re: edelbrock tunning tip
Quote:
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#8 |
Between Trucks...
Join Date: Mar 2002
Location: Los Angeles, CA.
Posts: 3,830
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Re: edelbrock tunning tip
The primarys have metering rods and springs. There are little doors on the top of the carb to access them. This is a great tip for trying to figure out which springs to run.
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Beat it to fit, Paint it to match... ![]() Last edited by Sinister; 02-27-2010 at 11:47 AM. |
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#9 |
Redefining LowBudget
Join Date: Mar 2009
Location: lebanon Cow Hampshire
Posts: 4,538
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Re: edelbrock tunning tip
I looked at miine and see what he's talking about..I guess one of the reason I love the Edlbrocs is that they run very well out of the box..so I never fussed with it
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#10 |
Moderator
![]() Join Date: May 2007
Location: Southern Cal
Posts: 20,005
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Re: edelbrock tunning tip
X 2. They also run very well even after sitting on a shelf for 10 yrs.
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1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man |
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#11 |
Registered User
Join Date: Jan 2009
Location: colorado springs
Posts: 479
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Re: edelbrock tunning tip
The metering have two stages, power and cruise, if you look at the rod it should be stamped (example 73/47) 73 would be the cruise mode which is the fatter portion of the rod plugging more of the jet letting less fuel flow through the jet, the 47 would be the power mode wich is the tapperd lower portion of the rod that plugges less of the jet letting more fuel flow though. Now the position of the rod in relation to the jet is controlled by vaccum that wants to pull the rod down into cruise mode and a spring under the piston that the rod is hooked to that wants to push the rod up into power mode. The spring and vaccum work against each other. At low rpm or cruising speed vaccum is high wich overcomes the spring pulling the rod down putting the cruise mode of the rod into the jet allowing less fuel flow. At hard acceleration or WOT, vaccum is low and the spring overcomes the vaccum pushing the rod up and putting the power mode portion of the rod in the jet allowing more fuel flow. If your spring is to strong it can overcome the vaccum and put your rod in the power mode at low rpm causing a rich mixture, or if your spring is to weak it will not overcome the vaccum leaving you in the cruise mode causing a lean stumble. Now all that being said you can and should still use a vaccum gauge when determining which spring is right for you, but the tip I posted is just that, a tip , I like many others like to tune and tinker. I had an idea, tried it and I thought it worked pretty well so I passed it on. If you like to take your carb out of the box mount it and trust that it is calibrated perfect for your application thats fine. I dont disagree that your carb is running fine but if you havent tuned it to your motor and elevation, I guarantee you are leaving some performance and economy at the table.
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#12 |
Redefining LowBudget
Join Date: Mar 2009
Location: lebanon Cow Hampshire
Posts: 4,538
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Re: edelbrock tunning tip
thanx for taking the time to type that all out it makes a ton more sense now...
I take it you can buy diff springs to fine tune it
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1970 C10 CST fleetside 472 ....big dreams little cash... SunShine Syndicate.. ![]() Mikes Sandwich Fair Run OCT 8th 2011
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#13 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: edelbrock tunning tip
Yes you can buy a kit from Edel. that has different springs, rods, & jets. You have to disasemble the carb to change the jets but the rods & springs can be change from the top.
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#14 | |
Registered User
Join Date: Nov 2009
Location: Goshen, AR
Posts: 150
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Re: edelbrock tunning tip
Quote:
Why would you put an RV cam in a 350 and then "down-tune" the carb? Does not make sense to me. Anybody got an idea?
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GROVE STREET CUSTOMS est. 2005 ![]() 67' C10 LWB/350/T400 69' C10 SWB/454/T400 71' C10 LWB/383/ 72' C10 SWB/350/T350 15' Crew Silverado/6.2 |
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#15 |
Keep On Keepin' On
Join Date: Apr 2006
Location: Oklahoma
Posts: 417
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Re: edelbrock tunning tip
It would be SWEET if someone did a very detailed thread with many pics fine tuning a Edelbrock carb (of course b/c I have one)...I heard Edelbrocks are suppose to be pretty straight forward but I bet a thread by someone who KNOWS what they are doing would be very beneficial to members like myself...FAQ worthy possibly!!
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07 Avalanche Z71 92 Mustang 5.0 GT (Triple White w/ 53,000 miles) 72 SWB Chevy w/ PS, AC, 350/350 Current Project ....In paint shop getting body/paint work done (Corvette Velocity Yellow)... http://67-72chevytrucks.com/vboard/s...d.php?t=157669 |
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#16 | |
Registered User
Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: edelbrock tunning tip
Quote:
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#17 |
Redefining LowBudget
Join Date: Mar 2009
Location: lebanon Cow Hampshire
Posts: 4,538
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Re: edelbrock tunning tip
^^ nice I'm sure to make my truck run like junk when I'm done..LMAO
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1970 C10 CST fleetside 472 ....big dreams little cash... SunShine Syndicate.. ![]() Mikes Sandwich Fair Run OCT 8th 2011
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#18 | |
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Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: edelbrock tunning tip
Quote:
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#19 | |
Keep On Keepin' On
Join Date: Apr 2006
Location: Oklahoma
Posts: 417
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Re: edelbrock tunning tip
That will work too!! Thanks
Quote:
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07 Avalanche Z71 92 Mustang 5.0 GT (Triple White w/ 53,000 miles) 72 SWB Chevy w/ PS, AC, 350/350 Current Project ....In paint shop getting body/paint work done (Corvette Velocity Yellow)... http://67-72chevytrucks.com/vboard/s...d.php?t=157669 |
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#20 |
Registered User
Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: edelbrock tunning tip
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Oscar '72 Shortbed Fleetside '95 Jimmy 4X4 '69 GMC Custom Camper |
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#21 |
Registered User
Join Date: Jun 2009
Location: Berkley, Massachusetts
Posts: 235
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Re: edelbrock tunning tip
Hi fleet 72, thanks for the video link, very helpful
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