I put a Street Demon 750 on my "stumbling" 440

[74Rallye]

I've got a 440 with low vacuum that's had a off idle dead spot since day 1, 10 years ago. I did learn many things trying to tune around it. Now I have a 4sp in the car and the stumble made the car undriveable without breaking things.
This week I bolted a 750 Demon on. It's incredible! No more bad manners. The low rpm driveability is incredible. Best money I've spent for a long time.

[JB400]

Glad you fixed your problem.  What carb was on it to begin with?

[SRT-440]

I'm betting an Edelbrock.

I've got the same stumble with my 440 and 800 Eddy.

[lloyd3]

Just to clarify, a "stumble" is a momentary loss of power when coming off of idle? If that accurately describes it, then I battle that occasionally as well.

[Rolling_Thunder]

Usually it can be traced back to the transition - the Edelbrocks for some reason don't seem to give quite enough fuel as the blades open in most cases - the three hole adjustment arm only does so much - I had good luck tuning around stumbles with upgrading the size of the squirter nozzle itself.

[Kern Dog]

A few years back I had a 360 2 barrel in a 1 ton truck but it was tired and I wanted more power for the work a man does with a truck. I screwed together a 440 from an RV. I had some '452 heads rebuilt and milled .060 to bring compression up to around 9.0 to one and used a 284/484 cam. I used a 2800 stall converter and a rebuilt 727. The carb I had was a OEM 1971 Carter 4 barrel from a 440. I had a trusted local shop go through it since I'd never built a factory type carb before. The engine always ran like crap with that carb even after having them go through it again. It wouldn't idle below 1500 rpms and WOT performance sucked ass. I finally chucked that POS into the recycle pile and swapped on a Holley 750. Immediate improvement. I could actually idle it down to under 500 if I wanted. It scrammed at WOT. It peeled out as long as I had the guts to stay in it. It towed great, climbed grades great and got about 9 mpg on the freeway with 4.10 gears. Not good, but hey...it was 1970s tech, 1970s aerodynamics, etc.
Carters are okay for totally stock engines but add a bigger cam and they suck. The Edelbrocks are based on the Carter design and carry the same curse.

[74Rallye]

It was an Edelbrock 800. I guess they work on Chevys? I tried a 750 for about a year, then an 800. I did everything I could to get those cars to squirt more fuel. Drilled the squirters, added a 4th hole on the pump shot arm, ran the primaries rich, idle screws didn't have much effect, dialing back the timing helped, but that killed power. The Demon is SO much better with the low rpm driveability. I haven't had time for a WOT tuning session yet.

[myk]

I've got the edelbrock stumble as well.  I hate this 'carb.

Edit-what Demon 'carb did you buy, 'OP?  Was it the 1903? What other parts did you have to buy to get it to fit?  Any issues with tuning or adjustment?

[74Rallye]

I went with the 1904. I had a hard time deciding between the composite main body and the metal main body, but I think it'll have better hot start manners with the composite.
The extra parts you will need are the Chrysler throttle cable adapter, PCV nipple, and what ever is needed for a kick down cable. I also ordered the step up spring kit.
I started with the softest step down springs and the maxim pump shot. It fired right up. I upped the idle adjustment and was off. I would like to get an O2 sensor verify my mixture, but it feels good and I can come out on the clutch just above idle. Dang I love it. I used to think of my engine as a bloated pig of a bitch on a good day. Now, on the bottom end, it's smooth, controlled and precise even with the timing bumped up. I can't wait for some more driving time, but it's raining now.

[myk]

I went with the 1904. I had a hard time deciding between the composite main body and the metal main body, but I think it'll have better hot start manners with the composite.
The extra parts you will need are the Chrysler throttle cable adapter, PCV nipple, and what ever is needed for a kick down cable. I also ordered the step up spring kit.
I started with the softest step down springs and the maxim pump shot. It fired right up. I upped the idle adjustment and was off. I would like to get an O2 sensor verify my mixture, but it feels good and I can come out on the clutch just above idle. Dang I love it. I used to think of my engine as a bloated pig of a bitch on a good day. Now, on the bottom end, it's smooth, controlled and precise even with the timing bumped up. I can't wait for some more driving time, but it's raining now.

[/quote

A composite carb?  Wow that's a new one for me.  What are the perceived downsides to using a composite 'carb? 

[74Rallye]

Plastic can change shape over time, especially with lots of heat. The quality of the composite material really counts. If it warps, it's a big problem. Plastic main bodies were used on the old Thermoquad carbs.

[RIDELIKEHELL]

I am going to ditch my Eddy and go with a quick fuel or Holley knock off as well. The idle circuit has little adjustment and my 68 suffers from the "Stumble" as well. Can't wait but no $ right now but can I ask how much yours was ??

[Dino]

Best thing I did was ditch the eddy and install a thermoquad in its place.  A composite body demon would be my first choice.

[myk]

I am going to ditch my Eddy and go with a quick fuel or Holley knock off as well. The idle circuit has little adjustment and my 68 suffers from the "Stumble" as well. Can't wait but no $ right now but can I ask how much yours was ??

It's like $345-400 or so.  Not a bad price IMO...

[74Rallye]

Best $354 I've ever spent.

[JR]

Got any installed pics of your engine?

Your thread has inspired me to finally get rid of my six pack which has never ran right and convert to a 4bbl. I'm pretty much sold on this carb.

What intake are you using?

[myk]

Got any installed pics of your engine?

Your thread has inspired me to finally get rid of my six pack which has never ran right and convert to a 4bbl. I'm pretty much sold on this carb.

What intake are you using?

Dude if you've got a 6bbl setup I'd try to work it out...

[JR]

I hear ya man, but I've had this six pack on the car since 1999, and I've never gotten it to run right ever. Replaced center carb with a new one, multiple rebuilds, read every tuning guide I could get a hold of, etc.

Just had the needle and seat stick again and completely flood my crankcase with oil. For the third time this year. Thought it was a problem with the new fuel pump or regulator, but I've narrowed it down to the carbs. Again. I can't take it anymore.

The 1904 Street Demon like the OP has seems to be getting great reviews all over the net. Seems to be almost set it and forget it. Sure would be nice not to have to fool with the carbs every week.

[fy469rtse]

One word guys,
Ron will back me up on this , just ask for god and his written word will appear to apeze the masses
Proform , is the word , there was a thread on the carb you guys are discussing, member was ready to bin it
I have bought both , street duty vac secondary's , bigger mechanical race for racing
Worth a look

[74Rallye]

I'll have to get a pic while it's still shiny! It's in a 74 Charger with a 440 with an Edelbrock Performer RPM intake with a drop base air filter. The filter base was modded to fit an Edelbrock carb with an electric choke. I also have a power bulge hood that gives me a little extra clearance.

[JR]

Thanks for the good info man. I take it your 440 combo is a mild street engine? Also, say if you had a flat hood, do you think you would have clearance then? Or is a scoop/bulged hood necessary with that combo?

Also, I do like those performs, but $$$

[74Rallye]

The carb is sitting on a thermal spacer and a Performer RPM. I've got about 1 1/2" of space with a power bulge hood and a drop base air filter.

[JR]

Damn that looks great under there. Appreciate the pics, i just ordered the performer RPM, gonna pick up the carb next week.

Nice work man.

[Laxy]

Great to hear you got such a good result with the carb change, I'm going through a similar thing at the moment. Have just replaced my old Edelbrock 750 with a new QuickFuel Slayer 750 and already the 440 is running so much crisper.

Have battled for the last few years with stumbles, flat spots and poor idle. Can't just blame the Eddie though, it looks like my Carter electric fuel pump has loosened up a bit and may be pumping a little more than it used to (ran fine for years with no regulator), the fuel bowls on the QuickFuel are filling up like both floats are set too high, but they aren't! Just waiting on a fuel regulator in the mail then can really see how this thing runs.

Strangely I have the same Eddie carb on a hot 360 and it runs perfectly, also a 600 Edelbrock on my 265 Hemi which has been amazing since I bolted it on 14 years ago brand new. Used to swear by them but they just don't seem to handle big block Mopars?

Going to pull this one down to see if there's anything obviously worn/damaged inside.

[74Rallye]

Strangely I have the same Eddie carb on a hot 360 and it runs perfectly, also a 600 Edelbrock on my 265 Hemi which has been amazing since I bolted it on 14 years ago brand new. Used to swear by them but they just don't seem to handle big block Mopars?

Going to pull this one down to see if there's anything obviously worn/damaged inside.

I've also used Edelbrocks on other engines with great results. It just didn't work with my 440 combo.