Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: 70Sbird]
#443787
08/20/09 02:55 PM
08/20/09 02:55 PM
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Joined: Oct 2007
Posts: 288 Birmingham, England
Mick70RR
enthusiast
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enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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I tried for 2 years to get rid of that off-idle bog and gave up in the end. The 750 eddy carbs are famous for it, try doing a search around other performance car forums. I tried every mod I read about and although I made some improvement I never did get rid of the bog completely. I bought a double pumper in the end. I've heard that the Thunder series AVS style carbs don't duffer with the same problem. They would still give you that stock look and an 850cfm is available..
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: Dougsmopars]
#443792
08/21/09 01:58 PM
08/21/09 01:58 PM
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Joined: Nov 2004
Posts: 1,760 Port Alberni, British Columbia
MoparDonny
top fuel
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top fuel
Joined: Nov 2004
Posts: 1,760
Port Alberni, British Columbia
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Quote:
with a big cam there isn't enough vac to hold down the metering rods during idle. They stay up at full rich. The air/fuel screws do little if anything in this condition. I've only seen this problem with eddies when installed on big cam motors. Mine only had 7 inches of vac at idle in park and 3 to 4 inches at idle in gear. Now with initial timing set at 20 car runs super with no stumble. But did need to recurve the mech advance in distributor to keep total at 38 degrees
with a 280 MP cam the mixture screws WILL need to be adjusted out.Manifold vacuum is too low to pull fuel through the idle circuit. If he has 10 inches of vacuum at idle in park I'd be suprised. Mine was a tad lower. I think the stock orange springs in a 1407 or 1408 Eddy may be a little stiff. I think I had blue stepup springs in mine but if he has over 8 inches of vac in gear the orange shouldn't create a stumble. More timing will help everything too. I welded the slots on my distributor to give me 18 initial and 34 total.
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: SomeCarGuy]
#443793
08/23/09 04:48 PM
08/23/09 04:48 PM
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Joined: Jan 2003
Posts: 75,282 A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,282
A gulag near you.
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Quote:
If he wants it to look stock he needs to find a Carter AVS or second choice would be the Eddy AVS.
He should get the EDDY AVS , the preformer RPM 750 HAS ISSUES ...
anyone ever compare the size of the squirters on an original AVS to the ones on the EDDY ??
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: Dougsmopars]
#443797
08/23/09 08:33 PM
08/23/09 08:33 PM
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Joined: Sep 2004
Posts: 2,492 NJ
Annie
top fuel
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top fuel
Joined: Sep 2004
Posts: 2,492
NJ
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: Annie]
#443798
08/23/09 09:12 PM
08/23/09 09:12 PM
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Joined: Jan 2003
Posts: 5,270 Missouri
MY340
master
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master
Joined: Jan 2003
Posts: 5,270
Missouri
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I must be the only #1407 Edelbrock 750 cfm AFB carb owner that's happy with their carb. It's 2 yrs old with no problems & very good performance. Installed a $6 manual hand choke last week and now even starts easy when sitting for a week.
1970 FE5 Duster 360/904/3.91's SOLD
1973 TB3 SpaceDuster 340/4spd/4.10's SOLD
Moparless for now but when the opportunity is right I'll have another one.
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: MY340]
#443799
08/24/09 12:03 AM
08/24/09 12:03 AM
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Joined: Jan 2003
Posts: 75,282 A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,282
A gulag near you.
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Quote:
I must be the only #1407 Edelbrock 750 cfm AFB carb owner that's happy with their carb. It's 2 yrs old with no problems & very good performance.
Installed a $6 manual hand choke last week and now even starts easy when sitting for a week.
Even a blind squirrel finds a nut ... there are also those that say they have NEVER been screwed over by Frank Mitchell or Jim Pattie
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: JohnRR]
#443800
08/24/09 02:38 AM
08/24/09 02:38 AM
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Joined: Feb 2003
Posts: 2,819 Sobieski Wi
bee1971
master
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master
Joined: Feb 2003
Posts: 2,819
Sobieski Wi
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I can pull some threads if need bee - Just let me know , and trust me i talk from experience with the 1407/1411 paper weight about the off idle - And then if you fix that you still have a carb that doesnt perform PERIOD !!!
Some great quotes
Now, in regards to the 750 version, just SAY NO! The carb is a slug. It has the worst signal of anything we have ever tested/dynoed, and is just not an efficient or powerful carb. In plain words it is a . censored The 500-600cfm versions are great, the 750cfm is unworthy of being on an engine. Best Regards,
Sam - Pres/CEO Century Performance Center, Inc.
383 Dyno in "Moparts Tech Archives"
All the aftermarket carbs tested ran fine with the stock calibration except one...the EDELBROCK 750, #1407. this one ran very poorly.....it didnt really do anything well. it was just flat out lean everywhere. idle, part throttle cruise, WOT...and it didnt like to take a load at all. when getting ready to start a pull and going to full power, the motor would fall right on its face, then try to recover....finally recover, and then you could start the pull. i found this to be pretty interesting because i also had on hand a Carter AFB 750 manual choke version which ran perfectly fine everywhere. decent throttle response, good part throttle cruise A/F ratios, decent idle A/F ratio with the mixture screws out only 2 turns, and the WOT A/F ratio was right where it should be, and it had a pretty flat fuel curve as well. i was running short on time, so i just continued on my testing of other things. when i was done for the night i pulled apart the Ebrock carb to see if someone had recalibrated it. this is not a new carb, but was pulled from my friends 396 Chevy yesterday morning. he's been running on the street, and didnt really indicate there was any kinds of problems with it, but there was an indication that another friend of his may have changed some jets or something. well....that was not the case. it had all the stock jets, rods, and springs, and had no dirt or debris inside. the calibration was just that far off from ALL the other aftermarket carbs. IMO, the Ebrock carbs are set up for motors that are much milder than what most people are building. well, most people i know anyway anyway....back to the trenches.....
1971 Dodge Charger Superbee 2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded Siberian Huskies
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: MY340]
#443804
08/24/09 09:48 AM
08/24/09 09:48 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
You guys are so funny!
Maybe my Edelbrock 750 thinks it's a Holley?
You know like a wolf in sheeps clothing.
Plus my mild combo runs high 12's with slicks and as the previous owner included several times slips with the receipts.
put a holley 750DP and it'll run 2 tenths better....maybe more. If it doesn't I'll buy you a case of your favorite beverage.
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Re: off idle stumble with Edelbrock 750 - suggestions?
[Re: 70Sbird]
#443806
08/24/09 11:39 AM
08/24/09 11:39 AM
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Joined: Jan 2003
Posts: 75,282 A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,282
A gulag near you.
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Quote:
Wow lots of activity here over the weekend! I ran the car on Sunday, intake vacuum was 8-9 inches of vacuum at 700 rpm low idle. I moved the mixture screws out an additional 1/2 turn (now 3 turns out), and switched the vacuum advance to the full vacuum fitting, instead of the ported fitting, and the car seemed to run slightly better, but not much. I've been reading the Edelbrock manual and looking for direction there as well, lots of info and combo's for tuning, but no mention (That I found) on off-idle changes.
I would put it back to the ported position or you'll have to much timing when it's not needed .
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