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#1
11-03-2011, 06:27 PM
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Edelbrock 800cfm carb question
Hey guys, what is the Ideal jetting for a E-brock 800cfm carb on 455. As of right now when I jump on the throttle it wants to fall on its face. When I easy into the throttle it seems to respond pretty well. The accellerator pump seems to have a good shot coming out of it. I feel that my old 600cfm carb had better throttle responce.
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#2
11-03-2011, 06:52 PM
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Quote:
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... 
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#3
11-03-2011, 07:15 PM
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Oh thanks its PN 1412
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#4
11-04-2011, 08:12 AM
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No amount of jetting is going to correct that problem (unless it's the AVS version). There is no adjustment for the opening rate of the secondary airflap on their AFB clones. It will help to put the correct spring under the pump. For some reason, millions of those carbs were sent out with the same spring under the pump that's on the pump. Fighting against each other, this really hurts pump shot when you go quickly to full throttle.
Several years ago I obtained two of the Edelbrock 750cfm AFB clones to set up for some dyno testing, in conjunction with these articles: http://www.highperformancepontiac.co...lts/index.html http://www.family-source.com/cache/862955/idx/0 The Edelbrock carbs failed initial testing so miserably (HUGE stumble going quickly to full throttle) that I took them out of the deal. My 1977 Pontiac q-jet outran a well prepared Holley 850 DP, dyno and at the track, so not much mentioned in the magazines about that either. My recalibrated 1977 Pontiac Q-jet went on to outrun, dyno and at the track, every carb tested against it to date, 850 Demon, HP 950, and 800 CFM Edelbrock AVS, so it gets little mention anyplace other than a blurb here and there that I put on a thread......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#5
11-04-2011, 10:40 AM
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Cliff,
don't mean to step on any toes in here. Are you taking in any carb work and when would be a good time to send to you. I won't need the carb back till March- April. |
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#6
11-04-2011, 10:58 AM
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Cliff is right about the air vane problem on non AVS carbs. My 750 Edelbrock was doing the same thing because the secondary air vanes were opening too fast & causing a lean condition that the engine had to fight its way through until the gas got moving through the secondaries. I solved the problem by putting in the air vane out of an old scrap carter AFB that was off a GTO & so was set up for a Pontiac engine.
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By diligent effort I seem to be prolonging my adolescence to total absurdity. John D. MacDonald |
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#7
11-04-2011, 12:16 PM
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Quote:
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#8
11-04-2011, 02:54 PM
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Spring under the pump. When I still took those in, most had the same spring under the pump that was on the pump. Doesn't make any difference whatsoever what springs you put under the power pistons, they are all the way up at full throttle with any of them.
Currently, we are backlogged about 8-9 months on carb work......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), Last edited by Cliff R; 11-04-2011 at 03:02 PM. |
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#9
11-04-2011, 03:37 PM
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Edelbrock does offer a accelerator pump with a stronger duration spring that may help, the Edelbrock part # is 1468. The spring is VERY stiff in my opinion so use a pump in the afb/avs clones with a spring that we had wound for us that works for our needs.
I hope this helps Henry @ oles carb |
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#10
11-04-2011, 05:51 PM
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Would we be referring to the spring on the pump assembly needing to be changed, the assembly as a whole as it is only 9.95, or the spring inside the chamber that the pump shaft rests in.
Thanks and sorry for all the questions |
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#11
11-04-2011, 06:03 PM
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Quote:
Henry @ oles carb |
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#12
11-04-2011, 06:20 PM
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would 1982 also work as well as the 1468. PN 1982 say that "High performance pump gives additional pump shot volume"
http://www.summitracing.com/parts/EDL-1982/ |
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#13
11-04-2011, 06:54 PM
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apparently that PN 1982 is for the Q-jet so I just awnsered my own question
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#14
11-04-2011, 07:45 PM
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Maybe that spring under the pump was for calibrated for Chevy (Brands X) engines and not Pontiacs?
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#15
11-04-2011, 08:09 PM
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I had that problem of the secondaries opening too fast with a couple of Carter's AFB carbs, the 9625 and the 9750. My cure for it was to slice the counterweights, then reposition and weld them to delay their opening. My belief is that they were all calibrated for Chevies and the Pontiacs gave too strong a vacuum signal causing them to slam open immediately. Once I did that they worked well.
Of course, it's a tad difficult to fine-tune the opening rate in that manner, though.
__________________
Rich The real democratic American idea is, not that every man shall be on a level with every other man, but that every man shall have liberty to be what God made him, without hindrance. Henry Ward Beecher "The problem with socialism is that you eventually run out of other people's money." Margaret Thatcher |
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#16
11-05-2011, 09:25 AM
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SDGoat619,
I have the Edelbrock 1413 on my 455 and it runs like a raped ape. No hesitation or sputter at all. When I first put it on, I had the same problems as you, so I purchased a calibration kit that contains an assortment of rods, jets, and springs. It took me a few tries to get it calibrated, but here are the settings: Referring to your owner’s manual on page 14, change the step-up spring to the Plain, @ 8” Hg. Turn to page 30, and set your primary metering to #13, which is 2 stages rich in cruise mode, and 1 ½ stages rich in power mode. On page 31, set your secondary metering to 2 stages rich. Finally move the accelerator pump linkage to the top hole. You may also have to look at your timing. Mine is set at initial 14 degrees with total timing of 32 degrees all in by 3000 RPM. Good Luck, Dan
__________________
Plans are what you make when you want to hear God laugh!! |
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#17
11-05-2011, 09:48 AM
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anyone running the Edelbrock with a cast iron intake?
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#18
11-05-2011, 12:17 PM
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Quote:
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#19
11-05-2011, 12:19 PM
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Quote:
I milled the front to back dividers out of a stock big block iron intake, so a friend of mine could use one on his 454 w/o an adapter plate. An adapter plate may be neded...
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down...
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#20
11-05-2011, 12:40 PM
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Quote:
Dan
__________________
Plans are what you make when you want to hear God laugh!! |
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