Adjusting an Edelbrock carb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Troy Campbell · 07-18-2008, 05:04 PM

Hey has anyone adjusted a 1406 or 1409 600 cfm Edelbrock carb. I have put a fuel pump regulator on it, it reads 5 psi. When you get on the acc, the truck stumbles badly. If you ease into the acc, it will run fine. If you mash it to the floor, it will backfire through the carb. I heard if you put a fuel pump regulator, you have to set the float level in the card, I do not know how to do that. Thank you in advance.

tkmad · 07-18-2008, 05:15 PM

Sounds like your accelerator pump is not working properly. Check the linkage to make sure it is being actuated. If so then the diaphragm may be torn or the valve may have some crud in it.

Troy Campbell · 07-18-2008, 08:25 PM

Thank you for the information, i will look at it.

67dragtruck · 07-18-2008, 09:44 PM

Does it only do it when you mash it quickly. If you ease it down does it still do it?

Tom

Husker · 07-18-2008, 09:49 PM

Interested also, My Jeep does the same thing
Ron

BarryB · 07-18-2008, 09:57 PM

I ran my pressure at 2.5 - 3 lbs.That what I was told to run for an edelbrock.

Troy Campbell · 07-19-2008, 10:22 AM

It does it when you mash on the gas, if you ease into it, it stumbles some, but not near as bad. I have replaced the fuel pump yesterday, I believe the carb needs adjusted, maybe even smaller jets put into it.

blukangoo · 07-19-2008, 10:35 AM

I have rebuilt a 1406 and a 1407 and they work fine.
Is you timing set right? Is your vaccum advance on the Disi hooked up.

Might not be the carb.

**Green Machine** · 07-19-2008, 10:39 AM

Ours did that after we changed heads and added headers, ran fine before. Bought the tuning kit for the 1406. First we tried a richer rod/jet in the kit, making the power mode richer but leaveing cruise alone. Tha t helped. we then went to the stiffest power valve spring and then adjusted the accel pump for max shot. We ended up ordering a rod not in the kit that keeps the cruise mix the same but is 2 stages richer on the power side. Runs great now, but I want to go back now and try a smaller pump shot and try a weaker step up spring to really fine tune it. Also went to 98 jets in the rear, stock was 95 in the back.

Go to the Edelbrock site, you can download an print the tuning manual for their cards, tell how to set floats and has charts for jet and rod combinations.

ChevLoRay · 07-19-2008, 11:20 AM

www.edelbrock.com has tuning tips and tech stuff for their carbs.

07-18-2008, 05:04 PM	#1
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Adjusting an Edelbrock carb Hey has anyone adjusted a 1406 or 1409 600 cfm Edelbrock carb. I have put a fuel pump regulator on it, it reads 5 psi. When you get on the acc, the truck stumbles badly. If you ease into the acc, it will run fine. If you mash it to the floor, it will backfire through the carb. I heard if you put a fuel pump regulator, you have to set the float level in the card, I do not know how to do that. Thank you in advance.

07-18-2008, 05:15 PM	#2
tkmad Registered User Join Date: Mar 2008 Location: Thousand Oaks Ca Posts: 51	Re: Adjusting an Edelbrock carb Sounds like your accelerator pump is not working properly. Check the linkage to make sure it is being actuated. If so then the diaphragm may be torn or the valve may have some crud in it.

07-18-2008, 08:25 PM	#3
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Re: Adjusting an Edelbrock carb Thank you for the information, i will look at it.

07-18-2008, 09:44 PM	#4
67dragtruck Registered User Join Date: May 2001 Location: Bethlehem, GA, USA Posts: 389	Re: Adjusting an Edelbrock carb Does it only do it when you mash it quickly. If you ease it down does it still do it? Tom __________________ No more dragtruck for me. I'm building a new ride though. It's a '71 fleetside, 400 sbc, 700R4. Working on it now, finally. Soon to have Edelbrock Pro Flo EFI, Vintage Air, 1 piece windows, buddy buckets, etc. My new build thread: http://67-72chevytrucks.com/vboard/s...17#post2861817 Best pass with the old dragtruck: 5.32 @ 131.6 mph 1/8 mile w/ a 1.25 60' Fogger/Plate 2003 Best pass with the street 406 hydraulic roller motor w/ mild plate tuneup 5.93 @ 114 mph 1/8 mile w/ a 1.29 60' 2003 or 2004

07-18-2008, 09:49 PM	#5
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: Adjusting an Edelbrock carb Interested also, My Jeep does the same thing Ron __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

07-18-2008, 09:57 PM	#6
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	Re: Adjusting an Edelbrock carb I ran my pressure at 2.5 - 3 lbs.That what I was told to run for an edelbrock. __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff! Last edited by BarryB; 07-18-2008 at 09:58 PM.

07-19-2008, 10:22 AM	#7
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Re: Adjusting an Edelbrock carb It does it when you mash on the gas, if you ease into it, it stumbles some, but not near as bad. I have replaced the fuel pump yesterday, I believe the carb needs adjusted, maybe even smaller jets put into it.

07-19-2008, 10:35 AM	#8
blukangoo Neighborhood Pickle Slinger Join Date: Jan 2007 Location: Cadolzburg, Bavaria, Germany Posts: 2,224	Re: Adjusting an Edelbrock carb I have rebuilt a 1406 and a 1407 and they work fine. Is you timing set right? Is your vaccum advance on the Disi hooked up. Might not be the carb. __________________ -------------------------------------------------- My C10 Diary Our cars: 1966 Chevrolet Chevelle 396 - TH350 1968 Chevrolet C10/CST 327 TH400/375 1969 Corvette Stingray 350 - Muncie Manual Trans 1969 Chevrolet ElCamino 350 - TH400 1970 Cutlass Supreme Convertible - 350 Rocket - TH350 1973 Camaro LT - New Engine Done - TH350 1973 Corvette Convertible 454 - TH400

07-19-2008, 10:39 AM	#9
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Adjusting an Edelbrock carb Ours did that after we changed heads and added headers, ran fine before. Bought the tuning kit for the 1406. First we tried a richer rod/jet in the kit, making the power mode richer but leaveing cruise alone. Tha t helped. we then went to the stiffest power valve spring and then adjusted the accel pump for max shot. We ended up ordering a rod not in the kit that keeps the cruise mix the same but is 2 stages richer on the power side. Runs great now, but I want to go back now and try a smaller pump shot and try a weaker step up spring to really fine tune it. Also went to 98 jets in the rear, stock was 95 in the back. Go to the Edelbrock site, you can download an print the tuning manual for their cards, tell how to set floats and has charts for jet and rod combinations. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0 Last edited by Green Machine; 07-19-2008 at 10:41 AM.

07-19-2008, 11:20 AM	#10
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Adjusting an Edelbrock carb www.edelbrock.com has tuning tips and tech stuff for their carbs. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.



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