Edelbrock 750 cfm or 600 cfm carburetor for 454 stock engine.

Which cfm of carburetor do you recommend for Edelbrock carburetor on a 1984 Chevy C30 crew cab with a stock engine? I'm looking for fuel economy. It has air conditioning and power brakes/power steering if that makes a difference.

The 600 will run and work just fine. That being said a 750 would be my choice. If you do heavy towing you may want/need the extra oomph.The original quadrajet would have been at least 750 cfm. Fuel economy is dictated by your right foot if everything else is tuned/working properly.

Not trying to cause a disturbance lol, but why Does it have to be an edelbrock?

squaredeal91 said:

Not trying to cause a disturbance lol, but why Does it have to be an edelbrock?

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My Edelbrock 2161 intake also takes Quadrajet. It's that the Edelbrock I have has a idle up solenoid. The 750 CFM Edelbrock carburetor is malfunctioning so I wonder if I have too much CFM. When the engine is hot it would stall. See the solenoid?

86burban said:

My Edelbrock 2161 intake also takes Quadrajet. It's that the Edelbrock I have has a idle up solenoid. The 750 CFM Edelbrock carburetor is malfunctioning so I wonder if I have too much CFM. When the engine is hot it would stall. See the solenoid?

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It's probably boiling the fuel from heat. Maybe float is high. Fuel expands when hot.
If you're fuel line runs along the intake or valve cover it should be moved or insulated underneath it to help. And a 750 edelbrock is usually jetted for a big block I think. No comments on the solenoid other than maybe base idle could be too low? Stall how? Stall when slowing down and stopping because of float being too high?

squaredeal91 said:

It's probably boiling the fuel from heat. Maybe float is high. Fuel expands when hot.
If you're fuel line runs along the intake or valve cover it should be moved or insulated underneath it to help. And a 750 edelbrock is usually jetted for a big block I think. No comments on the solenoid other than maybe base idle could be too low? Stall how? Stall when slowing down and stopping because of float being too high?

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It would stall when I'm driving. I start it up and it would stall when I put the transmission in drive. Gotta wait till it cools down for issues to go away.

86burban said:

It would stall when I'm driving. I start it up and it would stall when I put the transmission in drive. Gotta wait till it cools down for issues to go away.

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Could still be carb. Or could be timing issue. Or possibly a vacuum leak

Having similar issues with my qjet. I added a modified Mr. Gasket spacer, removed the carb side fuel filter and e-pump fuel filter and replaced with an inline filter, and rebuilt the carb with a walker set. I still need to test drive it but if it continues to stall on me, I'll redo the fuel line from the frame; either reroute the metal fuel line or replace/reroute it with a braided line. I can't exactly describe what happened but last time I stalled I tried some street side mechanics and started unscrewing the air horn and I'm pretty sure I heard a hiss or some gurgling or something. I must have released some pressure or something but when I screw the air horn back on, it ran again and I was able to make it home. Not sure if it's a vapor lock, carb, or fuel delivery issue, these are my solutions to fix it. If none of the above work, I'm switching over to edelbrock. Probably the #1906 or something.

86burban said:

It would stall when I'm driving. I start it up and it would stall when I put the transmission in drive. Gotta wait till it cools down for issues to go away.

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Could be that the primary jets and metering are stuck shut. I know this happened to me once and I couldn't give the engine any load at low RPMs. I had to limp back home on high RPM for the secondaries to open up with the load of the empty truck going down hill. Thankfully I was in my neighborhood. When I took apart the carb, the power piston was slammed shut somehow. I took apart the carb not too long ago and there was still a high amount of friction on the power piston. I think I need my carb replated, but for the same price I can just get a new carb.

The 600 will work better for what you are wanting. Make sure it is clean inside, floats set correctly, jetting set for altitude that you are at. Edelbrock manual has all the info.
Make sure that you have a return line to the tank to prevent vapor lock. Maybe put a plastic 1/2" spacer to help with the heat transfer.
I also like to block off the heat risers on the manifold, but you have to take the intake manifold off to do that.

If it indeed proves to be a heat issue, Edelbrock makes a carb spacer that has insulating qualities. Edelbrock part number 9266.

As already mentioned, first make a couple of checks of the existing setup.
- Is it a 3 port fuel pump with a return to the gas tank? The return helps keep fuel cooler when the carburetor float dead-heads the flow. With dual tanks you should have a six port solenoid that switches both fuel feed and return lines.
- Do you have an operational tank vent line and charcoal canister, and is the canister purge line connected? You need to have good tank venting if you want fuel to flow.

Also make sure you add an intake pad insulator and a spacer for the Edelbrock or Quadrajet. The insulating gasket and a 1" phenolic or wood spacer should help. Do not use a metal spacer.

The best carb spacers are wooden believe it or not lol

The 600 would be a better choice if you are using 5000 rpm as redline. The quadrajet can be sized to big and still work great on any engine because of the secondaryair door design they won't flow 750cfm unless your engine can use 750 cfm. The smaller carbureator will have a better vacuum signal for crisper acceleration.

I run a 500cfm on my K5 with a 350. It's an Edelbrock AVS2 with annular boosters. Throttle response is crazy fast and it drives great.