My 440 runs like crap under load

I'm finally getting my 68 Charger out on the road. It runs awful at anything more than 1/3 throttle. It just bogs and runs like crap.

I'm looking for ideas on where to start.

It feels like it has too much fuel and is flooding out, but I pulled a plug after my last run and it looked perfect. If the car is standing still, the engine starts and revs really smooth.

When I installed my Mopar electronic ignition, I ended up at around 16 degrees initial timing, and 34 at high rpm. (That was about a year ago, I haven't gone back and checked this again yet).

Any suggestions on where to start looking? I can I tell if its a fuel issue vs. a timing advance or ignition issue?

Thanks!

What kind of carb are you running? Holley or Edelbrock? There's a ton of variables that it could be. Start with simple stuff first; If it's low fuel flow, a simple thing to do is change the fuel filter. Since pulling the plugs doesn't show them being wet, it's not getting too much fuel. In keeping with the fuel issues, check the float levels in the carb too. If they're set too low they won't fill properly. If it runs like crap under 1/3 pedal, is it a constant pedal or a stomp of the pedal? In other words, does the car "buck and surge" at cruise but run smooth when you floor it? Does it stumble off idle or only at cruise? A cruise stumble could mean it's running lean or you have too much advance on the distributor at higher RPMs and can be remedied by turning the screw inside the vacuum advance to retard the timing. Give us some more info: how long has the car been sitting, what carburetor you have, engine rebuilt or just stock, what's already been replaced, etc. Hope that may start the diagnosis....

Cheers

yeah need a little more info, however 34* is not that much..you might want to try 36* at 2400 and w/o vac advance. Also if you are running a Carter-brock, I've had the choke suck shut on me at hard romps....
Also If it's a holley and it's falling flat it could be float level or not enough jet.

Did it ever run right with the current parts?

Change fuel and maybe the air filter if they have much age at all. I would change the fuel filter no matter what. Maybe one a clear one for a short time and see if any crud is getting sucked out of the tank, then change back to a steel filter when it is sorted out.

Wire the choke open to cut that out of the picture.

More info:

Carb is edlebrock. The car was last registered in '89, and I know it wasn't driven since at least 2001. So I have no idea if it ever ran right.

The base idle is real smooth, and I have decent vacuum, so I don't think it has any kind of cam in it. I think I'm dealing with a stock 440 that came out of a 1974 vehicle.

At quarter throttle, the car accelerates and runs OK. If I go from idle to 1/4 throttle, the car takes right off with a little wheelspin and no hesitation at all. If, at cruise (around 35 MPH), I go to half throttle, or WOT, it bogs. It continues to bog for as long as I have my foot in the throttle. It is not a case where it bogs down for a few seconds and then takes off. (i.e. - does not "buck and surge" as was asked above.

If I take my foot back off the pedal, and coast for a few seconds, I can then go back to 1/4 throttle and keep driving. Although at that point it starts to have a hard time at low RPM's. It wants to stall if I'm idling up the hill in my driveway back to the garage. I have to give it more throttle than I should to keep it running. (Hmm - sounds like a fuel issue after all).

Choke is a manual one. If it was sticking closed, I assume my plugs would foul, and they are not.

Vacuum advance is hooked up. I haven't yet tested to see where it is coming in, and how much.

So - sounds like:
Check Fuel Filter
Check Float Levels
Recheck timing and advance.

old gas

Well if it hasn't been running last since 2001, then yeah, it may be old gas and it may also be that the old gas in the carb could have varnished over and be clogging who knows what inside the carburetor. It's probably safe to say that if it's been sitting for a while you may need to rebuild that carb and give it a good cleaning. Stalling up an incline sometimes can mean float level problems. That's a common occurence on some cars that may stall when going around a corner too fast. The float level is not right. Believe me, right out of the box my float level was WAAAAY off and had I not fixed it the car never would have ran right. You can find the flaot adjustment setting and "how-to" on Edelbrock's website in PDF form. Defenitely flush out that old gas, add a new fuel filter,(and consider new lines eventually) and check the float levels and inside of the carb for any leaks or gunk build up. And while you're at it, check ALL your vacuum lines. If they are rotted and causing leaks, it may also complicate things. Check those and report back! Good luck

Cheers

Check also for arcing plug wires.

I have seen ignition coils that are failing have similar symptoms as well. They would operate fine at low RPM's then start to flutter and have no power at higher rpm's.

Thanks for the responses.

1) Not old gas. Tank was dry when I bought it. We had to winch it onto a trailer when I bought it cause it wouldn't start. When I got it home, and added gas, it fired right up. (And we all felt pretty stupid)

2) New coil (not that that means its good...) Its just some crappy aftermarket performance coil that I think I bought from Autozone.

3) Edelbrock carb was new. The previous owner put it on after he bought it in 2001, but the car was never driven. I suppose the float level is still suspect. Could be: carb was added in 2002, gas was added to the car, an then it sat for years. But - previous owner said he started it every 3 months or so and let it run for a while. He was definately a car guy (but he was a chebby guy that bought a mopar).

4) Don't get me started on arcing plug wires. I THINK I have the wires all safely away from the headers, but there are at least 2 plug boots that rest nearly right against the header. But - I suspect it would misfire all the time if that was the problem, not just when I get into the throttle. I know this is a future problem waiting to happen once I'm able to drive the car for more than a mile at low speed.

ok...wheres the arm? meaning what hole? Try one up or down (the accel pump) also turn all the screws in then out one. Start the car adjust for best vacuum. Then set your timing to 36* total at 2400rpm. Then turn the idle down to around 850 and re-adjust for best vacuum. Then go for a rhomp, if it doesn't ping try 38* total.

See what springs are under the rods.

Check the pump shot adjustment like was said.

Check the WOT adjustment while you are at it.

And wire the choke open. Don't assume anything.

Check Accelerator Pump shot adjustment. Use one of the holes for the least amout of travel on the plunger and see what happens.

Smooth idle tells me vacuum is advancing and initail timming is at least close. Cause a stockish 440 loves more timming.

accelerator pump shot tip in

Is this 'new' edelbrock carb a performer series 750cfm by chance? Those carbs had some quality control issues from new.

I think this might be a combination of things, since the car was never really sorted out after a lot of work was done to it.

I changed the fuel filter, re-timed it (it was way off, for some reason), and did a major change to the carb throttle linkage. While messing around with things, it looked like at WOT that the secondary linkage wasn't being activated. (That was probably most of the problem).

Anyway, its way better now. I had almost forgotten that throaty sound when the secondaries kick in.

But, after a couple hard accelerations this car still won't idle. It idles and drives fine until I do a couple WOT pulls. When I slow down the engine just dies. No sputtering, just "done", as if I'd turned it off. It'll fire right back up, but unless I keep the RPMS pretty high it'll just die again.

This sounds fuel related to me, but I can't see why it would only do this AFTER a couple WOT runs. I haven't checked the float levels yet - going out to the garage now to do that.

sounds like you're on the right track. good luck

Quote:

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Is this 'new' edelbrock carb a performer series 750cfm by chance? Those carbs had some quality control issues from new.

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That's exactly what it is. I just checked the float levels and they were way off. Drop was 3/4" too low, and the upper limit for fuel shutoff was also nearly a 1/2" low. The previous owner probably just took it out of the box and popped it on the car, without checking anything.

I also moved the pump rod up one notch just for the heck of it. I think I might be able to get away with another degree or two of timing, but I should probably do a test drive with the new carb changes first.

Except - it started raining. Darnit! It'll probably blow right over, but I live on a dirt road. Doing WOT runs in the mud is probably not a good idea.