StingrayL82
Nampa, Idaho
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Edelbrock also reproduced Quadrajets for a while and called it the QJet. You might be able to find one of those and use it.
The Edelbrock 1406 throttle bore diameters are 1-7/16" on the primaries and 1-11/16" on the secondaries. The primaries fall within the specs of the 800cfm and 850cfm ThermoQuad primaries, which were 1-3/8" and 1-1/2", respectively. The secondaries on both versions of the ThermoQuad were 2-1/4", IIRC, much bigger than the 1406.
Here's a link to Edelbrock's carbs, to help you out, Eric: Edelbrock Performer Series Carburetor Owner's Manual
Fred
Retired Army Guy
2005 Monaco LaPalma 37PST
Workhorse W24 chassis
8.1L Vortec
Allison 2100 MH
Onyx Color Scheme
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VintageMopar
Missouri
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It comes back slowly for us old folks.
I remember the AFB which would be Carter or Edelbrock did real well cornering, acceleration and braking because of the dual float bowls. But it was prone to flood out or boil dry under hot soak conditions. That would be like full operating temp, shut engine off for 10-15 minutes, then try a re-start. The fuel in the float bowls would percolate out the main nozzles and flood the engine, or just boil dry, then it wouldbe a long crank to re-fill. Being all aluminum they would soak up too much heat. A class C application does not seem a good thing, but thick insulating spacer between carb and intake did help a lot with this issue.
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StingrayL82
Nampa, Idaho
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VintageMopar wrote:It comes back slowly for us old folks.
I remember the AFB which would be Carter or Edelbrock did real well cornering, acceleration and braking because of the dual float bowls. But it was prone to flood out or boil dry under hot soak conditions. That would be like full operating temp, shut engine off for 10-15 minutes, then try a re-start. The fuel in the float bowls would percolate out the main nozzles and flood the engine, or just boil dry, then it wouldbe a long crank to re-fill. Being all aluminum they would soak up too much heat. A class C application does not seem a good thing, but thick insulating spacer between carb and intake did help a lot with this issue.
Correct me if I’m wrong, but isn’t that why Carter came out with the ThermoQuad, to eliminate the boil over issue the AFB had?
One of the things my engine builder insisted on was a thick gasket. I went one step further and bought a NOS GM aluminum carb shield and modified it to fit the ThermoQuad. I should have zero heat issues, knock on wood.
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Griff in Fairbanks
AK
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Thank you, VintageMopar, for mentioning known problems with Carter AFBs and Edelbrock carburetors based on the AFB design. I vaguely recall, from decades ago, mention of this problem in magazines.
I have long known -- and mentioned on this thread and elsewhere -- about heat-related carburetor problems in motorhomes, vans, and similar COE-type vehicles.
This is why I advocate using one or two marine inline bilge blowers to force cool air into the doghouse and around the upper part of the engine. In addition to improving fuel economy and engine efficiency, this should reduce (but not eliminate) the AFB hot soak problem.
I also advocate OEM, aftermarket, or custom cold air intakes. While these will improve fuel economy and engine performance, cold air intakes will do little, if any, to reduce the AFB hot soak problem.
Both bilge blowers and cold air intakes are suitable for all COE-type vehicles, regardless of carburetor or other types of naturally aspirated air-fuel systems. Of the two, cold air intake is most effective for improved fuel economy and engine performance.
Editted to remove question that VintageMopar already answered in his post above. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/doh.gif "doh") . (Reread his post and ... finally noticed everything he said.)
The AFB hot soak problem means extended engine cranking to refill the float bowls. Extended engine cranking is hard on the SLI (engine) battery, battery cables, starter relay, and starter motor. It's also hard on the ignition coil because the start circuit bypasses the ballast resistor, sending full battery voltage to the coil.
(Until recently, I had not considered and didn't recognize potential damage to the coil. I believe it was VintageMopar who brought this to my attention -- as well as everyone else.)
This is another reason to prefer electric fuel pumps, located in or near the fuel tank(s) instead of OEM mechanical engine-mounted fuel pumps. (Electric fuel pumps can refill and pressurize the fuel system before cranking the engine. They can also eliminate vapor lock problems.)
* This post was
edited 02/16/18 02:03pm by Griff in Fairbanks *
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
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Griff in Fairbanks
AK
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If you go to an electric fuel pump, wire it to the IGN circuit only. It's tempting to wire the pump to both the IGN and START circuits. However, wiring it to both creates the potential for the START circuit to be partially or fully energized when the ignition (key) switch is in the IGN position. (While electricity tends to choose the easiest path, it also "wants" to go everywhere it can -- anything and everything that leads back to the negative battery or alternator terminal.)
Wiring it exclusively to the IGN circuit means the pump would not be energized when the ignition switch is in the START position. So, you'd be relying on fuel stored in the carburetor float bowls. (This is the situation anyhow with mechanical engine-driven fuel pumps.). This means your starter and ignition systems needs to be in top condition to ensure a quick start. The battery and battery cable also need to be in top condition, for this reason as well as other reasons.
In the case of a AFB hot soak, I'd recommend a separate momentary (pushbutton or spring-loaded toggle) switch. With the ignition key on the OFF position, pressing and holding the momentary switch would provide a separate circuit to the electric fuel pump, allowing the pump to 'prime' the fuel system and refill/top-off the carburetor float bowls.
This set-up would also be useful in hard to start engines. (Mostly big blocks -- 383, 413, and 440 cu. in.). If the engine doesn't fire up in less than a minute of cranking, you could turn off the key switch, press and hold the momentary switch to 're-prime' the fuel system, and then try again to start the engine.
You might even find the momentary switch useful as part of your normal starting procedure. i.e., press and hold the 'prime' switch for 5-10 seconds before trying to start the engine, to ensure the engine has adequate fuel.
If this description is confusing, let me know. Normally, I'd provide a circuit segment diagram but computer problems prevent me from creating a diagram at this time. (I hope to have my computer fully operation by early next week.)
Eric - this plays into your dual fuel (propane and gasoline) conversion. I don't want to discuss it here because your efforts are relatively unique. PM or email me when you're ready to discuss it.
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Grandma Griff
Alaska
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New member here Griff's wife.
Decided to join to keep an eye on him.
Griff in Fairbanks' Wife
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StingrayL82
Nampa, Idaho
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Grandma Griff wrote:New member here Griff's wife.
Decided to join to keep an eye on him.
HAHAHAHAHAHAHAHA!!!!!!!!!
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Leeann
Maryland
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Joined: 08/22/2006
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Grandma Griff wrote:New member here Griff's wife.
Decided to join to keep an eye on him.
This is very important. He does get into trouble ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/awink.gif "awink")
Good to see you!
'73 Concord 20' Class A w/Dodge 440 - see profile for photo
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Ballenxj
Formerly Southern Nevada, Idaho now
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Grandma Griff wrote:New member here Griff's wife.
Decided to join to keep an eye on him.
Howdy and Welcome Griff's wife. You had better keep an eye on him. I've heard a rumor that he runs around naked while welding. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/eek.gif "eek")
Downsizing ">
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Griff in Fairbanks
AK
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Ballenxj wrote:I've heard a rumor that he runs around naked while welding.
Actually, Grandma Griff and any nearby family members all pick up fire extinguishers whenever I pick up one of my oxy-acetylene torches. (Geez, just because I lit my son's Bronco II on fire ... and a bunch of leaves ... and a wooden sawhorse ...)
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