Is my Edelbrock 600 too small for a stock 1973 400?

[WH23G3G]

My friend that has a 1980 El Camino with a .040 over 350 is using a 600 Edelbrock 1406 and has had nothing but problems trying to get it to produce any power at all and even one was leaking gas through the throttle shaft. I've got a 600 Edlebrock 1400. It's got power but it's not enough to even spin the tires. When you stomp on it it will take off but it doesn't feel like the secondaries are kicking it because it should be a lot faster than it is. I don't know if I posted but I drove it to work and back two weeks ago and it did good until I got 2 miles from home and it just totally shut off at a red light. Putted through the intersection backfired through the exhaust. All that time I had it at work though two guys fooled with the mixture because I thought the idle was too low. When it stalled out on the way home I parked it and came back later that night, a friend readjusted the screws and I drove it home no problem. I called the mechanic the worked on it and he told me I shouldn't have had anyone fool with the carburetor. One guy from a mechanic shop was trying to help me get it started and he turned the mixture screws all the way in, it backfired through the exhaust and blew up one of my mufflers. So I'm replacing both the mufflers with OEM aftermarket fit just to get it to the shop. But I know the original Carter Thermoquad flowed like 850CFM and this Edelbrock is only 600. Will I ever be able to make any power out of it? I'm using the Weiand Action plus or something like that, but it's basically stock replacement intake with no choke well. I always want to keep my dual snorkel original air cleaner. Do I need to get another carb? The shop I go to that is a Mopar fanatic swears by them and says he uses them on everything. What about a Demon carb? Do I need a 700 or 800?

[don duick]

I am no carburettor expert but I can tell you my experience. I had a 750 edelbrock carb on a stock 440 and I had similar symptons to yours it would backfire out of the exhaust and did not have much power. The previous owner of this carb tried to jet it to suit his small motor, turned out that the secondary jets were way too small and the primary jets were way too big. It ran rich at low throttle. and the secondaries were starving for fuel when they opened.  I then tried a 600 edelbrock carb and it runs great had so much more power and revved to about 5000 no problem. A 600 on a 400 should work fine check the jet sizes and metering rods.
Now another example, my brother has a 383 in his challenger and runs fine with a 600 carb we tried a 750 edelbrock carb and no good was too big for a stock motor. I don't think a stock 400 motor has much power anyway. I had a low compression 440 {7.5 to 1} in good condition and that did not have much power. 

[WH23G3G]

Well I knew it wouldn't have power like a 440 but the numbers back then weren't too far apart. The 1973 400 was 260hp and 335lbs-ft vs 280hp and 380lbs-ft. Even for a low compression motor the power it has now when driving doesn't seem to match OEM but it is still fast, eventhough I know the OEM numbers may have been off a little. It should however burn these little 14's off and I haven't been able to mostly because it bogs down when you mash the pedal to the floor. But I've got a Road and Track article with a 1973 fully loaded Charger SE 440 automatic, 3.23 gears, that they said ran 1/4 in 15.0 flat at 95mph. Which I don't think is horrible for a heavy car with a low compression 440. I've got 3.91 gears in a 8.34 sure-grip so it should get it up pretty quick. But I do think it needs some carb tweaking if I were to keep this carb. I do know that this 1400 Edelbrock I've got has the same size primaries .098 as my original Thermoquad did but my Edelbrock uses .095 secondaries and the original Thermoquad I think used .101 secondaries.

[69wannabe]

A friend of mine bought a 67 satellite and it had a 72 400 down in it with a 2 barrel carb. I put an edelbrock performer intake on it with a 1406 edelbrock carb and an electronic ignition kit to get it up and running and it ran great on there. I never even done any jet swapping or changing any metering rods. A few years later I rebuilt the original 383 to go back into the car and even put a small cam and hi po manifolds on it and used the same intake, carb, and distributor and got it going and never done anything but adjust the mixture screws and set the timing and it ran great til he sold it a few years later. That 600 should be a good fit for your 400 ci. You may need to check your spark plugs for fouling and check all your ignition system parts for wear or maybe timing issues.

[WH23G3G]

Yeah I had problems with another shop who got timing and didn't have the carb hooked up right. This Mopar guy that has a legitimate repair shop reset the timing for me, hooked up the choke correct, and installed a stud kit. He told me not to mess with the timining. It doesn't miss and it starts up easy. He told me when it was doing fine driving home that it might be an ignition issue. Ballast resistor, module, or coil. What's the most common failure on these cars using the electronic ignition? Now when I drove this car and it stalled on the way home it was pretty hot, like 90 outside, but the engine didn't overheat.

[cudaken]

WH23G3G Couple Of Questions

1 Does it stall on you when cold? If not, there is a good chances you are boiling the gas in the carb. Engine temp could be fine, but not in the carb.

2 Have you checked to see if the carb is at WOT when gas pedal is floored?

3 Did the Mopar Shop check to see if outer timing ring might have slipped.

4 Did the Mopar shop give you specks on the timing? Base timing, total advances and at what RPM?

When you took it to the Mopar shop, did you ask them just to make it run, or make it run like a rape ape? 

Far as a bigger Carb, they hurt off the line but make it up in the mid and top end. With 3.91's ripping the hides should not be hard! Far as not playing with the timing?  That is where most people leave HP on the table!

Assuming the timing ring has not slipped, shoot the base timing. Then give it a 2 degrees advances and take a test spin. On my Road Runner I went from 12 degrees to 16 degrees base timing and it it felt like a different motor.

Ken 
   

[Cooter]

Considering that engine prolly came through with a 750-850 thermojunk from factory, I'd say it was bout dead nutz on.

[WH23G3G]

I'm trying to fix my exhaust system so that I can drive it back to the shop to get the carb tuned. I'm having issues installing my new muffler and wanted to get some ideas on it before I mess it up. I got the whole exhaust kit from Year One through Accurate Exhaust. The muffler that I had blow up because the guy was fooling with the mixture screws had a part number on it of 10287. They're like $100 a piece. I just bought some OEM replacement 18230 Walker SoundFX mufflers from Summit that I can use for awhile. But the muffler that blew up slipped over the tailpipe and exhaust downpipe. This new muffler from Walker slips inside the tailpipe good but the downpipe needs to be expanded. Should I expand the downpipe or the muffler itself? Does it matter whether the muffler slips inside the pipes or over it?

[nvrbdn]

i believe its all about jetting and tuning.  i have a 383, 40 over, 484 lift cam, holley and edlebrock both said i wanted a 600. ran lean. had the 750 dp already. my buddy that can do magic with a carb came over and tuned the 750 and she runs awesome. so i got a holly 600 and an edlebrock 600 ready for the for sale table.

[cudaken]

WH23G3G, what the heck is your real name? My name is Ken whats yours?

Far as which one to expand, which either is easiest! With out be there I would say the muffler.  Far as power, really should not matter but if I had to wager a guess tailpipe would be the way to go but maybe .010 of a HP if that? 

I am with Jim on Carb Tuning, if not tuned right I don't care what carb is on the 400, it will be a pig out of the hole. But, my Gut (and it is a big one!) says look at the timing after you get the muffler on. Next would be carb tuning.

Jim, how do I get your Carb guy to be my friend as well? 

Ken

 

[John_Kunkel]

Considering that engine prolly came through with a 750-850 thermojunk from factory, I'd say it was bout dead nutz on.

The Thermobog may have 800 cfm capacity but a stock 400 probably uses less than 600 cfm of that....that's the idea behind the huge secondary air door, one size fits all (the 318 also used the TQ).

[WH23G3G]

The mechanic that worked on it told me a timing spec that he put it at which I think he said was the total timing. Don't quote me on it but I think he said it was 30 degrees total timing. But I don't even know if it that's right. Anyway I asked him how close is it to the 7.5 BTC as what the factory had set for a 73 400-4bbl Charger. He said it should be pretty close but I never went back and rechecked it because it starts up real easy and doesn't ping but thats probably because there's no miles on it. When I drive it back to his shop I'll ask him about the timing and ask him what he can do to the carb. As far as the mufflers I wasn't trying to change them to get anymore horsepower, I just bought the kit from Year One because I didn't have any exhaust to work with exhaust the HP manifolds. I just threw on some Walker 18230 OEM replacement mufflers to get me back on the road since the clown who messed with my mixture screws blew up one of my mufflers. I was telling my mechanic that I would be bringing it back to him and what had happened and he thought it was an ignition issue just randomly shutting off with no warning. I put a Mopar Performance orange box on there a few months ago, running a stock reman distributor, mopar performance restoration wires, accel chrome coil, and wells replacement ballast. Does anyone make a heavy duty ballast? I ordered a MP one from Summit but don't know if there is such a thing as a heavy duty ballast. I got one side muffler on but haven't felt motivated to do the other side yet. I'll keep updating as to what happens
     
Jon

[cudaken]

Hey Jon!

In your other post, did you not say there is a bigger aftermarket cam in the 400?  If it is, 7.5 BTDC is pretty soft! My 383 stock timing called for something like around 10 BTDC. With the 509 (pretty big over lap) Cam it was a real pig at the stock settings. Moved it up to 16 BTDC and it really woke up the engine. 30 Degrees total advances is again pretty soft. Most folks here want 34 total advances.

Cuda Ken

[WH23G3G]

Actually no I don't have a big cam. It's only an aftermarket cam from Sealed Power I think .458/.460 lift. It was the aftermarket replacement for a 73 Charger with a 400-4BBL. When I built the engine the only thing I added that wasn't in there was a Mopar Performance windage tray. It's got the 73 400-440 heads with 3 angle valve job by a local cylinder head company, .040 over flat top pistons, stock 73 cast crank, 73 Hp exhaust manifolds. I've got the Weiand replacement intake on it now. I saw the numbers for 400-4bbl Chargers back in 73, 260hp, 335lbs-ft. I was happy with that. So I tried to build it stock, I even had the right 73 intake and the correct 6321S Thermoquad restored. But the first clown I took it to where it sat up for 6 months couldn't get it to work right saying it was junk eventhough it was freshly restored and tested. All along the reason why because the intake was leaking. I bet it would've worked right but he told me why don't you just get an Edelbrock and be done with it. It wasn't for another 3 months that it took him to find out the intake was leaking. The Mopar mechanic had it up and running where I could actually drive it the next day after picking it up from the first clown mechanic. I just wanted a stock 73 Charger. I would've been happy with a 318 but seeing how this one does I'm not sure a 318 would've been as fun, wondering if a stockc 73 225 Charger would even move. I'm wanting to get it running where I don't have to be afraid of taking it out and stalling and get my a/c working. So then I can get it painted the way I want.