Edelbrock mid throttle problem

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TTC

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Hi!

I have a tuned 440 magnum and I have edelbrock 750 performer carburator.
My problem is that I can´t get it running well at mid throttle, so it is lacking power. I have been working with jets and testing , also been adjusting ignition advance multiple times. It works really nice but the power stays only at high rpm. Engine doesn´t bog or stall, it just misses power.

Many have said to me, that you have to change the carburator.. What do you think?
I have been adviced to buy quickfuel 850, with annual nozzle body

440 magnum
906 ported heads
10:4 compression
Compcams XE275HL-10 (in. 231, ex. 237)
727 with 1800 stall converter
Headers and 3" exhaust
(Power should be around 400hp)
 
I have the exact opposite issue with the same carb.

Idles well and good power but smells rich and can't seem to tune it out.

1969 10:1 440 with unknown somewhat lopey cam, presumably stock heads, truck headers and an 833 o/d.
 
Sounds like you might need to change metering rod springs and make sure the pistons aren't binding. You guys could probably swap springs and fix both problems... I'd also verify float level settings.
 
mguner said:
Sounds like you might need to change metering rod springs and make sure the pistons aren't binding. You guys could probably swap springs and fix both problems... I'd also verify float level settings.
Click to expand...

That's funny, but very possible. LOL
I have to agree on the jets, rods and springs being where the issue is and an air fuel ratio gauge would be nice here, even if temporary.
 
It would also be a good idea to take a look at your spark plugs after cruising. Just to verify what sounds like a lean condition. Possibly too light a metering rod spring or too fat a metering rod, too small a jet or a rod with a step in the wrong spot for your application. I would clean the metering rod pistons with steel wool so they are nice and shiny, get all the dust off and dip them in ATF. Make sure the piston bores are clean and smooth. If you don't have a tune up kit for these there are things to do but you risk ruining parts or eliminating your base line to go back to. You can thin the metering rods with emery cloth, measure your springs and either stretch (rich quicker) or shorten (fix rich idle) them incrementally.
 
It's in the tuning. That carburetor can run every bit as good as a Holley style. There is something on the primary side it sounds like that's not working properly. Since they are so easy to get to the primary rods, pistons and springs would be the first place I would look.
 
YY1 said:
I have the exact opposite issue with the same carb.

Idles well and good power but smells rich and can't seem to tune it out.

1969 10:1 440 with unknown somewhat lopey cam, presumably stock heads, truck headers and an 833 o/d.
Click to expand...

Yours probably needs a lighter primary piston spring. The loss of manifold vacuum at idle means you need less spring to pull the primary pistons and rods down into the jets to lean the mixture. You may even need a bigger rod. At least that's what your wife said. heh
 
I run the pink springs at 5,500 above sea level and have a nice smooth air fuel ratio at all but idle.
I run the idle slightly rich to help keep the heat down around town in slow traffic.

So in Florida I would think even lighter ones would be needed.
 
Keep in mind the Eddy's are more easily adjusted with rods than jets too. Changing the jet changes both steps of the metering rod, changing the rod usually allows you to keep one step the same and gives you 2 or 3 options for the other step. Springs are easy to change too

TTC-

If you're fine at idle, fine at cruise, and fine at WOT, then the idle setting is fine, the primary step of the metering rod is probably ok, and the secondary jets are ok. I would look at the second step of the metering rod and the spring. You could try a stiffer spring to bring the second step in sooner, and/or make the smaller step on the metering rod another size or two smaller and see if that helps. If there's no bog or anything, the transition to the second step on the metering rod is probably taking place at close to the right time, it's just not enough of a step.

YY1-

Opposite! Just like RRR said. Try a softer spring so you stay on the primary step longer. And maybe a larger diameter rod, at least on the primary step. The "lopey" cam probably means there isn't enough idle vacuum to keep the metering rods down on the primary step so you're going too rich. I'd try the spring first to make sure you aren't immediately going to the second step of the metering rod because of the lack of vacuum.

I run a Carter on my Challenger, actually have had a couple on there, and my g/f has an Edelbrock carb on her '55 Coronet and '71 F100. They're good carburetors, and I've found them to need a lot less adjustment than the Holley DP I'm running on my Duster. The rods and step up springs are super easy to change, no messing with gaskets or fuel at all. And usually you don't have to mess with the jets too much, although that requires taking off the top of the carb and messing with the gasket. Usually though the rods and springs can do most of the tuning. The only issue I've had with every Eddy or Carter I've had is that the fuel bowls will dry up after a couple days, so you have to crank fuel into the carb if they sit. The Holley DP seems more resistant to that.
 
Another possibility is the advance curve. You may not be getting enough timing at cruise RPM or if you are set up with manifold vacuum on the vacuum advance that may be making it sluggish in the mid range.
 
IMHO. if the engine is close to how chrysler made that engine. tune the carb close to the same jetting and springs that chrysler did. i have found that the eddy carbs are jetted completely diff than chrysler did. and the way chrysler did them is about as good as you can get.
 
moe7404 said:
IMHO. if the engine is close to how chrysler made that engine. tune the carb close to the same jetting and springs that chrysler did. i have found that the eddy carbs are jetted completely diff than chrysler did. and the way chrysler did them is about as good as you can get.
Click to expand...

Thats all well and good, BUT, the original Carter AFB's had 3 step metering rods and Eddy's have 2 step, so tuning a new one like the old ones really doesn't work.
 
Thanks for tips! Today I continued tuning by changing primary jets and metering rods back and forth. I also changed stiffer springs. I double checked the ignition timing and it is 14 initial and 37 total advance. Total advance occurs after 2500rpm. None of these settings changed the problem. I have used edelbrock carb tuning jet kit.

This problem is easy to notice, because when I am accelerating by using second gear only, engine first feels strong but then it takes time before you reach around 75% of the power, it really performs very well!!!
 
i for got to say that when changing jets and rods at the same time you can NOT guess at what you end up with. but i have posted a program that will do the calculation. may be some here can remember where it is. and some of the Carter AFBs on mopar did have the 2 step rods, that are shorter than the 3 step rods. with a flat lid, and the short jet. do NOT mix 2 step parts with 3 step parts. next hint: if the jet does not want to come out DONT force it. use a torch to heat the jet , when the flame color changes dump water on it. when cool it should come out. and you dont have to put them in tight just snug and they will stay in.
 
here is the link to the AFB / jet /rod program. that my son made. its a copy / reproduction of the one i did on the old Commodore 128. in basic. it will calculate any combination of jet / rod change and give you the % of change. but it can not tell WHAT jet / rod to run. that is up to you. *http://clarkehackworth.com/files/JetsAndRods.html
for the computer side tech support [email protected]
 
Many years ago I had a similar built 440 (.030 with MP 280-.474 cam,headers,performer rpm intake)with the eddie carb and we tuned it to death.I thought it ran pretty good.Took it to the track and ran it.Swapped on a box stock Holley 750 vacuum secondary with no tuning and went .20 quicker in the eighth mile.
Not bashing edelbrock so much as that was the turning point for me.I sold that edelbrock and haven't owned one since.
They are fine for cruising and start nice with an electric choke but for max performance a Holley always works better for me.

EDIT:
10.4-1 and 37 degrees total advance with iron heads seems kinda high to me unless you have a fresh air intake and some really good gas.Are you getting any detonation?
 
Hi!

Sorry for my late reply for this issue! Problem is solved now and car is running really great!!
I bought this quickfuel 850cfm annual douple pumper carb and after tuning it in dyno, car worked much better. But still something was missing.

I earlier bought purple cam 280/280 with 0,474 lift from my friend, that was supposed to be installed into my dart with 383 bb. We decided to install it to this 440 engine last saturday. The difference is so huge now compared to comp cam that it had earlier. Now I can say that it has true muscle power!!!

I have sent the comp cam back to the factory, because many have been thinking now, that it may have defects. This comp cam was only driven 1000km and it had also ticking noise, when i was driving on the highway. Now that problem is also gone.
Luckily we managed to get this car running in the end, but it took whole summer. Now winter is arriving here in Finland, so time to put the car in the garage.

Thanks for your information!
 
Engine was tested before it was installed into car. All the recommended additivies was used and I have always used kendall 10w 60 oil with zinc additive, so this should not be the problem. Also after the engine was started the first time, we kept rpm around 2500pm for 20 minutes.
Also the lubricant from compcams was used during the installation like the instruction recommended

Problem is somehow related to camshafts lobe, because there was pale grey area in every lifter, shape of the area was almost circle but offcentered.

Haven´t got reply from Compcams yet
 
after reading your post again about 2 step and 3 step rods. 65Val i did remember that chrysler did have some AFBs with 2 step rods. i think around early 60s maybe on 413s. i sure you all know to NOT mix any parts from a 2 step with a 3 step set up rods.
 
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