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#1 |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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So... I've got an Edelbrock 1406 that replaced the original QuadraJet ( I didn't do it, it came this way) I rebuilt the 1406...runs amazing, but I get significant rpm drop when I put it in gear (stalling) . Cold or hot it doesn't matter. What gives? I've done a complete tune up, plugs AcDelco R45ts (gapped to 45) new MSD 8mm wires(I know that means insulation) the HEI is a Delco and it is putting out about 15k volts on each lead and wire at the plug(zapped myself a few times testing... Ouch) timing is set to 12 dgrs advanced @ 800 rpm idle. Choke is electric and appears to be working/functional (choke flap is opening slowly as it warms)Vacuum gauge shows good vacuum hot or cold. My vacuum advance is connected to the vacuum port on the passenger side of the carb(swapping to driver's side port only increases in park idle speed) . I've sprayed carb cleaner on ever crack crevice and hose, I can't find a leak if there is one. Everything is set up per the Edelbrock set-up guide and everything I can find from the Google overlords. What am I missing?
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#2 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Another carb help...
Turn your idle down to 600 rpm.
Then check your timing. At 800 rpm the mechanical timing might be kicking in, |
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#3 | |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
Quote:
Tried this morning... No go, still does the same thing. Last edited by Kalums; 08-05-2024 at 09:48 AM. |
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#4 |
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Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: Another carb help...
Try it with the vacuum advance disconnected.
George |
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#5 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Another carb help...
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#6 | |
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Join Date: Feb 2011
Location: Modesto, CA
Posts: 2,188
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Re: Another carb help...
Quote:
is it the original cast iron manifold with a carb adapter, or is it a square bore intake manifold? Where do you have the idle mixture screws set, and do they actually change the vacuum signal/idle speed when you run them in/out? |
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#7 | |||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,936
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Re: Another carb help...
Quote:
Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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#8 |
Registered User
Join Date: Oct 2008
Location: Marianna Arkansas
Posts: 7,269
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Re: Another carb help...
Spray some carb cleaner around the base and listen for RPM changes when you hit the vac leak you have it will rev up. Jim
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#9 |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
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#10 |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
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#11 | |
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Join Date: Jun 2024
Location: Phoenix,AZ
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Re: Another carb help...
Quote:
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#12 |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
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#13 |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
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#14 |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
I understand that the Edelbrock is a much easier carb to tune/rebuild... But I do have the original Quadrajet... Would it be worth my effort to rebuild? Assuming it is rebuildable...
Do they make an electronic choke "upgrade" for the Quadrajet? |
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#15 |
Senior Member
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Location: San Ramon,CA
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Re: Another carb help...
I'm thinking you wouldn't get the idle speed down to 600 if there was a vac leak
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#16 |
Registered User
Join Date: Apr 2022
Location: Moorpark, CA
Posts: 755
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Re: Another carb help...
you really want VA using manifold port, not the timed one. You may have to back down "initial", aka base, timing a few degrees as VA will add some at idle likely. You want 20-24 degrees with VA connected so if VA provides 12 degrees advance, set base at 8.
Fairly classic symptom of bog. die, without VA on manifold vac when put in gear (automatic) if that is what is happening. Eddy carbs are dead simple to tune, basically a Carter AFB Timed port vac was a failed emission thing. Yeah I know the carb manual says use it, they basically have to. Just plg the timed port and use manifold vac for VA. Now adjusting VA to come in and how much is a different discussion but the 411 above should resolve the stall issue when put in gear. Vac leaks typically increase RPM so does not sound like that is happening |
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#17 |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
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#18 | |
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Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
Quote:
I went back and read you post again... And literally walked out to the truck to try this... When I have the VA plugged into the carb (timed port?) it runs rough (like I need new motor mounts... Which I have in the garage) at 12 dgrs advanced (manually set by me using a digital timing light) but if I turn my distributor ever so slightly til it is about 20 dgrs advanced it speeds up my rpms AND runs smoother. I can then turn down my idle to 800 rpm and it only drops to 650-675 when I put it in gear, still a drop but no stalling ...... My light bulb just came on... Was I manually retarding my timing? Too much?? Was I the "malfunction" *face palm* Last edited by Kalums; 08-06-2024 at 01:00 AM. |
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#19 |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
When setting "initial timing" should my VA be connected or disconnected?
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#20 | |
Senior Member
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Location: San Ramon,CA
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Re: Another carb help...
Quote:
What kind o' ignition are you running, btw
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1970 C10 Custom longbed 350/350 |
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#21 |
Senior Member
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Location: San Ramon,CA
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Re: Another carb help...
Initial timing should be with VA disconnected(and that hose plugged)
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1970 C10 Custom longbed 350/350 |
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#22 |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
Stock ignition, aftermarket AcDelco HEI
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#23 |
Registered User
Join Date: Jun 2024
Location: Phoenix,AZ
Posts: 33
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Re: Another carb help...
I.... Am an idiot... Or just nieve... It is currently too late for me to futz with this anymore tonight (kids are sleeping and V-8 currently with straight pipes AIN'T quiet) thank you for the assistance, I'm pretty sure you guys figured it out and I just need to put in the work. I will report back tomorrow. Thanks again.
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#24 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,865
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Re: Another carb help...
Here's my 2c. If you have vacuum assisted brakes, try it with that port (and any other vac. ports) on the carb plugged.If that's not it, you need to go back through that Edelbrock and check the idle circuit very carefully. Also, it would help if you answered Leftybass209's question; How did it run before you went through the carb? -BA
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent. Last edited by WorkinLonghorn; 08-06-2024 at 08:52 AM. |
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#25 | |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: Another carb help...
Quote:
Your timing marks aren’t accurate. Either the mark on the balancer is wrong or the timing tab is wrong or a combination of both. You need to find true top dead centre on #1 cylinder to see where your timing tab/balancer marks are at. |
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