440 with edlebrock carb, adjustment question...

[UH60L]

So, my car is finally running after 8 1/2 years.  It's a mutt '69 charger (originally a 318 car...) with a 440 bored 40 over, and running an edelbrock 750 performer carb.  We started it a few weeks ago and set the timing at 10 deg btdc (running a '70s era distributor with an MSD 6AL).

When accelerating from a stop it stalls, then after feathering the pedal, it surges a bit, then smooths out and runs like a champ.  (boy does it sound good!)

I ran this carb new on the old 440 that I had in the car back in 2006 and 2007, and I recall having to put in richer metering rods, because it was too lean from the factory.

I have tried running with the accelerator pump rod in all three holes.  The top hole seemed to be the worst, but all three still had some surging.

I have tried adjusting the idle screws, but it doesn't seem to "not stall" regardless of how rich or lean I make it.

Any suggestions would be appreciated.

[myk]

Have you swapped out the metering springs yet?  Putting in weaker or stronger springs will alter driveability also.  I had to switch to the heaviest ones to deal with my off idle bog; it's still not right but it's better...

[UH60L]

No, haven't done the springs yet, might try that on Monday.

[redgum78]

Have you set the idle mixture screw? It might help?

[myk]

No, haven't done the springs yet, might try that on Monday.

Do you have the tuning kit?  It might be a worthwhile investment as its got an assortment of jets, springs, needles, etc...

[BSB67]

When accelerating from a stop it stalls, then after feathering the pedal, it surges a bit, then smooths out and runs like a champ.  (boy does it sound good!)

A near stall or major stumble from a stop is not metering rods or springs.  It is likely badly adjusted idle mixture screws, bad accelerator pump, or a gummed up carb that needs a cleaning.

Really low initial timing could do it too.

Take off the air cleaner, lean over the fender so you can look straight down into the carb with the choke open. snap the carb throttle about half way open. Do both squirters spray a healthy stream of fuel?  Report back.

Does anyone know if a low fuel bowl fuel level cause the squirter pump well to go dry on this carb?

[tan top]

 whats the engine vacuum at idle &  in gear

[UH60L]

Ok, so while at a friend's house to fix my leaking sending unit, we checked the accelerator pump.  No gas squirting out at all.  Got a new one today and put it in.  The old one, the whole cup had come off and was wedged at the bottom around the spring.

Runs a lot better now, with just a minor surge just off of idle, probably mixture adjustment. (I'm at the lean end, 2 turns out on both screws)

As for the vacuum, we didn't check that actually.  I don't think I have a vacuum gauge to check it with.

I'll have to see if my friend has one (he's got a lot more tools/stuff than I do)

[myk]

I have the same off idle surge that you do.  Post up what you try to do to fix it...

[UH60L]

Well, I still don't have a vacuum gauge.  Tried some small adjustments toward the rich side with the idle mixture screws and it didn't seem to help.  I still have a surge/sputter as I come off idle.

If I kind of push past that spot it sort of jumps over the surge and takes off normal. (doesn't always work though, sometimes goosing it slightly causes it to sputter a bit)

The Edelbrock website videos say to run the mixture out to the rich side to fix this problem, but my local speed shop guy, that's got a crap ton more experience than I ever will, swears that you need to keep them at the lean end...   

I also noticed something, it seems that the red spring(carb to trans linkage) is overpowering the green spring(throttle return).  I have to tap/smack the gas pedal for it to drop back to idle sometimes while driving.  It'll cruise along at 35 mph with my foot off the gas until I smack it...

[Bobs69]

I have a 750 edelbrock with the electric choke.  I bought it brand new way back when.  I phoned the tech line quite a bit, they sent me a modified accelerator pump.  It still didn't fix the problem.  It's bothered me for a long time I don't even know if that is the issue!

I bought a used 750 holley double pumper, one of these days I'll put a rebuild kit in it and see what happens.

[UH60L]

The guy at local performance shop also said it could need a different spring on the accelerator pump, might be too stiff... not squirting at the right vacuum level.

I'm gonna see if I can get a hold of a vacuum tester this weekend.

[myk]

Well, I still don't have a vacuum gauge.  Tried some small adjustments toward the rich side with the idle mixture screws and it didn't seem to help.  I still have a surge/sputter as I come off idle.

If I kind of push past that spot it sort of jumps over the surge and takes off normal. (doesn't always work though, sometimes goosing it slightly causes it to sputter a bit)

The Edelbrock website videos say to run the mixture out to the rich side to fix this problem, but my local speed shop guy, that's got a crap ton more experience than I ever will, swears that you need to keep them at the lean end...   

I also noticed something, it seems that the red spring(carb to trans linkage) is overpowering the green spring(throttle return).  I have to tap/smack the gas pedal for it to drop back to idle sometimes while driving.  It'll cruise along at 35 mph with my foot off the gas until I smack it...

Your off idle bog is exactly like mine and other users of the Edelbrock Performers.  I've adjusted that thing every way possible, short of drilling holes into the thing to increase airflow/fuel like others have done.  The fact that the stumble goes away as soon as more fuel is added with the gas pedal makes me think that these these carbs are just too lean in that particular circuit.  I'm switching to a Proform or Holley 4160 when funds allow...

[69chargin]

I'm having this exact issue. Car starts right up, runs fantastic but there is this stalling action from a stop - exactly why you describe. We have rebuilt the carburetor (Carter), replaced the spark plugs, changed the radiator fluid, changed the thermostat (had a 160) to 190. We are still playing with the carb settings! Hoping we figure it out!

[myk]

What're your guy's timing settings at?  UH60L if you're still at 10* I'd try bumping that up to 18* BTDC like most of us are running.  Again, I still think this is a lean fuel issue with whatever fuel circuits carbs use when they're transitioning from idle to right off of idle...

[Bobs69]

Well, I still don't have a vacuum gauge.  Tried some small adjustments toward the rich side with the idle mixture screws and it didn't seem to help.  I still have a surge/sputter as I come off idle.

If I kind of push past that spot it sort of jumps over the surge and takes off normal. (doesn't always work though, sometimes goosing it slightly causes it to sputter a bit)

The Edelbrock website videos say to run the mixture out to the rich side to fix this problem, but my local speed shop guy, that's got a crap ton more experience than I ever will, swears that you need to keep them at the lean end...   

I also noticed something, it seems that the red spring(carb to trans linkage) is overpowering the green spring(throttle return).  I have to tap/smack the gas pedal for it to drop back to idle sometimes while driving.  It'll cruise along at 35 mph with my foot off the gas until I smack it...

Your off idle bog is exactly like mine and other users of the Edelbrock Performers.  I've adjusted that thing every way possible, short of drilling holes into the thing to increase airflow/fuel like others have done.  The fact that the stumble goes away as soon as more fuel is added with the gas pedal makes me think that these these carbs are just too lean in that particular circuit.  I'm switching to a Proform or Holley 4160 when funds allow...

I think so too.  Anyone want to buy a Edelbrock?

[UH60L]

Yeah, I'm still at 10 degrees advanced on timing.  I'm running a Mopar Performance version of a MSD 6AL with no ballast resister and a '70s era stock electronic distributor, and a stock coil.

Got a vacuum gauge today.

With car idling at 850 rpm and vacuum gauge hooked to the left front (normally unused) port on carb, it was at just under 20 PSI of vacuum.  I adjusted the mixture screws and got it to right at 21 inches and 850 rpm, but when I goosed the throttle it backfired through the carb.

I moved the accelerator pump rod from the top hole to the middle hoe and that seemed to be better.  Took it for a drive and it still isn't quite right but seems a little better.

I may move the accelerator pump rod to the bottom and see if that helps.  Might be that, now that my accelerator pump actually works, its giving it a little too much fuel maybe.

Just a note also, back when I got the carb new, it was too lean for my old 440 and would actually stall out when I hit the gas, so I go the next richer metering rods and installed them.  This engine is bored 40 over so I figured I might be a little lean or just about right with those metering rods...

[myk]

Are you going to change the timing?

[Just 6T9 CHGR]

Ive had absolutely zero problems with my 800 CFM Eddy Thunder series carb.  Pretty much spot on right out of the box.  I think this AVS style one is more Mopar friendly

[UH60L]

Are you going to change the timing?

I haven't yet.  I put the accelerator pump rod on the lowest hole, and it seems a lot better.  It's still not perfect, but it's a lot closer now.

So, 18 degrees, that seems like a lot.  Your car doesn't backfire or kick back when you start it with 18 BTDC?

[myk]

18 seems to be the new standard.  My car ran better when i put the timing there, with 34* total in by 2600 RPM.  Many of the guys here are running 18* or MORE initial.  They say you're supposed to keep bumping up timing until RPM's stop climbing/highest vacuum is reached but mine stopped at 24*; I thought that was too much and moved it back to 18.  I think Ron has his motor locked at 36*? 

[SRT-440]

My 440 has the same off idle stumble and stumble when going wot from a roll. It's done this from day one and the carb is a Edelbrock 800 cfm thunder series.
The car starts up fine, idles good, cruises good..just stumbles..I've learned to drive around the stumble some..but if u do a search on the internet many ppl have the same Edelbrock stumble.

[myk]

My 440 has the same off idle stumble and stumble when going wot from a roll. It's done this from day one and the carb is a Edelbrock 800 cfm thunder series.
The car starts up fine, idles good, cruises good..just stumbles..I've learned to drive around the stumble some..but if u do a search on the internet many ppl have the same Edelbrock stumble.

I'm surprised you haven't selected a new carb yet...

[69chargin]

What're your guy's timing settings at?  UH60L if you're still at 10* I'd try bumping that up to 18* BTDC like most of us are running.  Again, I still think this is a lean fuel issue with whatever fuel circuits carbs use when they're transitioning from idle to right off of idle...

We haven't tested it yet but it's on the list for next week! Will report back!

[Back N Black]

18 seems to be the new standard.  My car ran better when i put the timing there, with 34* total in by 2600 RPM.  Many of the guys here are running 18* or MORE initial.  They say you're supposed to keep bumping up timing until RPM's stop climbing/highest vacuum is reached but mine stopped at 24*; I thought that was too much and moved it back to 18.  I think Ron has his motor locked at 36*? 

I'm set at 24* with no issues.