Worth it to swap out 750 eddy for a 750 double pumper?

[MoparMotel]

I posted a while back about swapping the stock 625 carter for a 750 edelbrock and while the car does run a lot better it just did not give me the performance gains I was hoping for. After seeing how an 850 double pumper performed on a friends 460 ford big block last night I wanted to see what your thoughts would be on if I would see any gains going to a 750 double pumper.

Engine is numbers matching 383 rebuilt 1,500 miles ago.
Mild build- 10:1 pistons, factory intake and Hp manifolds, comp cam .470 lift, and as of right now 2 1/4 dual exhaust with flowmaster 40 series with no H or X pipe.

Basically this car only gets driven once a week or sometimes every two weeks so fuel mileage isn't a concern, just trying to make the most power I can.
Right now this thing won't even break the tires loose and has the famous off idle edelbrock stumble.

Also... The flowmaster 40 series on the car are for 2 1/2" exhaust and I only have 2 1/4 piping so sometime this week or next week I'm going to have my exhaust guy run all new 2 1/2" piping and do an H pipe as well.

[Budnicks]

I posted a while back about swapping the stock 625 carter for a 750 edelbrock and while the car does run a lot better it just did not give me the performance gains I was hoping for. After seeing how an 850 double pumper performed on a friends 460 ford big block last night I wanted to see what your thoughts would be on if I would see any gains going to a 750 double pumper.

Engine is numbers matching 383 rebuilt 1,500 miles ago.
Mild build- 10:1 pistons, factory intake and Hp manifolds, comp cam .470 lift, and as of right now 2 1/4 dual exhaust with flowmaster 40 series with no H or X pipe.

Basically this car only gets driven once a week or sometimes every two weeks so fuel mileage isn't a concern, just trying to make the most power I can.
Right now this thing won't even break the tires loose and has the famous off idle edelbrock stumble.

Also... The flowmaster 40 series on the car are for 2 1/2" exhaust and I only have 2 1/4 piping so sometime this week or next week I'm going to have my exhaust guy run all new 2 1/2" piping and do an H pipe as well.

I would say yes go for it, I know a ton of guys love them Edelbrock Performer, Carter AFB AVS & THermoquad carburetors, they have their place...  I prefer the Holley type carburetors for performance use though, I have had better performance with them, even in a side by side carburetor Holley & Carter swap at the track comparison... On multiple 2x4 carbs & restorations, I do like the Eddy or Carters... Just prefer the Holleys for performance apps.      Just my opinion, I don't want any hate mail...

[Chryco Psycho]

Yes , Check out Proform carbs

[MoparMotel]

Looked around a little bit, is the one I should go with the #4150 which reads 750 double pumper? Also what are some more things to wake this car up? I am not very happy with it's performance....I think my Duramax diesel truck would walk away from this thing in a drag race. Maybe headers, intake manifold, ETC?

[Dino]

I'm still learning all this stuff, and will do so for a looooong time to come, but this is definitely the place to gain the knowledge!

I think that apart from the 2 1/2 h pipe some headers would give you some noticable gains.  383's are nothing to compare to modern engines but they are not exactly slow to begin with.  Come to think of it, those diesels do have a boatload of torque your 383 doesn't have. 

What's the rest of your setup?  What year Charger do you have?  What rear end and gears?  I lost a bunch of power going from 3.55 gears to 2.94 with a 440, but it is a lot more enjoyable to drive.

[Budnicks]

Looked around a little bit, is the one I should go with the #4150 which reads 750 double pumper? Also what are some more things to wake this car up? I am not very happy with it's performance....I think my Duramax diesel truck would walk away from this thing in a drag race. Maybe headers, intake manifold, ETC?

I would help to have, a good aluminum dual plane 4bbl hi rise type performance intake {if it's going to be a street car, single plane if a drag car}, a good fuel mechanical or electrical pump & a fuel regulator if over 7psi, 3/8" pickup & 3/8" or #6A/N lines lines & fittings minimum, feeding the pump & carb, quality fuel filter 1 before the pump & 1 before the carb, headers, a free flowing exhaust preferably 2.5" 0r larger {your 2.250" will be OK though add a H or X pipe}, a gauze type air cleaner element like a K&N...  

[MoparMotel]

I'm still learning all this stuff, and will do so for a looooong time to come, but this is definitely the place to gain the knowledge!

I think that apart from the 2 1/2 h pipe some headers would give you some noticable gains.  383's are nothing to compare to modern engines but they are not exactly slow to begin with.  Come to think of it, those diesels do have a boatload of torque your 383 doesn't have.  

What's the rest of your setup?  What year Charger do you have?  What rear end and gears?  I lost a bunch of power going from 3.55 gears to 2.94 with a 440, but it is a lot more enjoyable to drive.

Engine rebuilt 3 years ago. Approximately 1,500 miles on rebuild.

Numbers matching 383 block
bored .30 over with 10:1 pistons-not sure what brand ( had local shop rebuild it )
factory intake and factory hp exhaust manifolds that have been jet hot coated
Edelbrock 750 with manual choke
factory dual snorkel air cleaner
factory rear end with 3.23 gears( no posi, only time I could actually get it to break loose only one tire spun)
factory distributor with pertronix kit
2 1/4 duals with flowmaster 40 series( soon to have H pipe installed )
rebuilt 727 with shift kit

I am going to take it to a friend of mine who works on mopars and have him set carburation and timing. I don't know if its timing or what but this thing has a horrible stumble when accelerating from a stop sign and when you really put your foot in it the car doesn't start pulling hard until after 3,500rpm. When holding the brakes and stepping on the gas the car won't even break the tires loose. Has no bottom end power at all.

[Dino]

That stumble seems to be common with that carb, I've had it happen a few times as well.

After your friend checks timing and a/f ratio go try to break the tire loose again.  From a stand still drop it in first and floor it, no braking or any of that, just gun it.  If your tire doesn't create a wall of smoke something's way off.  I used to do this with my 68 and a 383 all stock except headers.  Tires I had back then were 225 70 14 and it would smoke them (it, open end rear as well).  I am almost positive I had 3.23 gears.

If I do the same now in the 69 with 440 and same size tire with 2.94 open end it'll smoke the tire and stay put while it roasts the poor thing, when I let off a little it moves, floor it again and I can roast it well through 2nd gear.  With 3.55's it was a lot crazier still.   There's a quiet paved road just out of my sub with a really long tire mark, I was shocked when I drove passed it the other day and saw it, so much for quiet road!

When the engine was rebuilt, was it ever dyno'd?  Do you have any numbers off that engine regarding performance?

How's the rest of the car doing?  All brakes work and release as they should?  Suspension is ok?  Just trying to narrow it down here.

[MoparMotel]

Engine was not dyno'd when it was finished. I have not set the timing since I got it back from him, could something have changed since I got it back? The guy who rebuilt the engine is a Chevy guy, and mostly builds chevy engines at his shop, I wonder if he didn't know what he was doing when he did mine or are they not that much different?

He said he had a 69' Roadrunner with a 383 a while back and some friends who have gone to his shop seemed to trust him.

[Dino]

If he's good with Chevy engines I don't see how he would not be just as good with mopars.  If he did an engine rebuild then he should have set timing and a/f ratio.  If all he did was bolt in new parts then there's more work to do.  For all we know your engine is fine but your parking brake is stuck halfway down!

Honestly I don't see anything in your setup that would really hold you back.  There's always better carbs and intakes but stock should work fine.  Have you removed the snorkel to see if it improved? 

Now you did say you don't really care about fuel mileage and just want performance so I say remove the carb, intake manifold and exhaust manifolds, replace with proform or Holley carb with a Weiand, a holley street dominator or Edelbrock performer RPM and add some headers in the mix. 

I'm not all that familiar with cams.  How does it idle?  Nice and smooth or kinda race rough?

[1970Moparmann]

Yes , Check out Proform carbs

I have to second this.   I am VERY impressed with the throttle response of mine.   I'm planning on putting it on my Coronet.

[greenpigs]

If you go the Proform route make sure you get matching pieces if your building one from an existing Holley.

[Cooter]

Yes, Holley Double pumper all the way...

[68blue]

750 Holley DP on my 383 works fine.

Eddy RPM heads and mainfold, TTI pipes, Comp 21-223-4, 3.55 gears

Idle is slightly edgy but drives nice on the street.

[Chryco Psycho]

Engine was not dyno'd when it was finished. I have not set the timing since I got it back from him, could something have changed since I got it back? The guy who rebuilt the engine is a Chevy guy, and mostly builds chevy engines at his shop, I wonder if he didn't know what he was doing when he did mine or are they not that much different?

He said he had a 69' Roadrunner with a 383 a while back and some friends who have gone to his shop seemed to trust him.

A few years back we built a pair of identical engine for two friends trying to outdo each other , I ported the heads on both , tuned both , but one guy took his engine to a ford machinist , his engine made 205 RWHP on a Mustang Dyno , we then took the second car to the dyno with the engine I had fully built & we made an insignificant 50% more power on the same dyno , it made 315 RWHP .
A machinist can make or break the build .

[mopar2]

This is what Ron recommended for mine http://www.summitracing.com/parts/PRO-67213/  can't wait to get it and try it out 

[Budnicks]

Engine was not dyno'd when it was finished. I have not set the timing since I got it back from him, could something have changed since I got it back? The guy who rebuilt the engine is a Chevy guy, and mostly builds chevy engines at his shop, I wonder if he didn't know what he was doing when he did mine or are they not that much different?

He said he had a 69' Roadrunner with a 383 a while back and some friends who have gone to his shop seemed to trust him.

A few years back we built a pair of identical engine for two friends trying to outdo each other , I ported the heads on both , tuned both , but one guy took his engine to a ford machinist , his engine made 205 RWHP on a Mustang Dyno , we then took the second car to the dyno with the engine I had fully built & we made an insignificant 50% more power on the same dyno , it made 315 RWHP .
A machinist can make or break the build .

"I agree 100%"  the assembly is very important or at least as important as the parts selected,  just because some one is a "machinist" doesn't make them a good "engine builder"  , especially when it come to performance applications & techniques... Every style of build, or mnfgr. has their own idiosyncrasies & ways to extract the most power Ford stuff, Chevy stuff, Mopars stuff & others all have their own quirks  ... Always go to someone who is a specialist in the brands you choose to build...

[MoparMotel]

Little update.....

Took the car to a friend yesterday and he put the timing light on it..... Timing was 19 degrees at idle.... got the carb dialed in and timing set at 15... Car runs way better and starts a lot easier. I am going to run this carb for a month or so and see if I like it. The car still has the stumble off of idle leaving a stop sign, and he suggested buying the edelbrock jet kit and going up 2 sizes on the jets and see if this helps the stumble.

If I cannot get this carb dialed in perfect I will probably be ordering the Proform in the summit link above.

[MoparMotel]

Called edlebrock today and explained my motor and stumble and they are sending out new metering rods and lighter springs for free... Pretty good customer service!

One question I was wondering about is this thing has no low end power at all... Won't even break the tires loose with or without the brakes. Does this sound like carburetion or timing or the cam I put in it comp 270/470?

Hoping the metering rods solve the stumble and give me some low end power.

[Cooter]

Called edlebrock today and explained my motor and stumble and they are sending out new metering rods and lighter springs for free... Pretty good customer service!

One question I was wondering about is this thing has no low end power at all... Won't even break the tires loose with or without the brakes. Does this sound like carburetion or timing or the cam I put in it comp 270/470?

Hoping the metering rods solve the stumble and give me some low end power.

Depends on the rearend gear, stall speed of converter(If automatic), etc. as to how much TORQUE you need to "turn the tires over"...Carb tuning will only get you so far if you don't have enough engine. Remember, a 383 Chrysler BIG BLOCK has less stroke than a small block 350 Chevy....

[MoparMotel]

Called edlebrock today and explained my motor and stumble and they are sending out new metering rods and lighter springs for free... Pretty good customer service!

One question I was wondering about is this thing has no low end power at all... Won't even break the tires loose with or without the brakes. Does this sound like carburetion or timing or the cam I put in it comp 270/470?

Hoping the metering rods solve the stumble and give me some low end power.

Depends on the rearend gear, stall speed of converter(If automatic), etc. as to how much TORQUE you need to "turn the tires over"...Carb tuning will only get you so far if you don't have enough engine. Remember, a 383 Chrysler BIG BLOCK has less stroke than a small block 350 Chevy....

Gears- Factory 3.23's. Not sure on the stall, had the transmission rebuilt with a shift kit but not sure if he put a stall in.

[Challenger340]

Engine was not dyno'd when it was finished. I have not set the timing since I got it back from him, could something have changed since I got it back? The guy who rebuilt the engine is a Chevy guy, and mostly builds chevy engines at his shop, I wonder if he didn't know what he was doing when he did mine or are they not that much different?

He said he had a 69' Roadrunner with a 383 a while back and some friends who have gone to his shop seemed to trust him.

A few years back we built a pair of identical engine for two friends trying to outdo each other , I ported the heads on both , tuned both , but one guy took his engine to a ford machinist , his engine made 205 RWHP on a Mustang Dyno , we then took the second car to the dyno with the engine I had fully built & we made an insignificant 50% more power on the same dyno , it made 315 RWHP .
A machinist can make or break the build .

"I agree 100%"  the assembly is very important or at least as important as the parts selected,  just because some one is a "machinist" doesn't make them a good "engine builder"  , especially when it come to performance applications & techniques... Every style of build, or mnfgr. has their own idiosyncrasies & ways to extract the most power Ford stuff, Chevy stuff, Mopars stuff & others all have their own quirks  ... Always go to someone who is a specialist in the brands you choose to build...

Agreed,
being a "Machinist" does NOT neccessarily make one a good "Engine Builder"
however conversely,
IMO,
I have never seen a "GOOD" High Performance Engine Builder, who wasn't fully conversant with Machining, or was more than capable of Machining for themselves if required ?
Sooner later....it boils down to be able to GET, what YOU want, and being able to check it properly requires far more than "plasti-goop" !

Amazing how many supposed wonderful "Engine Builders" I have seen, have NO IDEA "how" to Machine anything.....wouldn't even know HOW to turn the Friggín Machine "ON" if you put them in front of it......yet rely solely on a "machinist" supposedly "doing his job" ?
These type "Engine Builders",
well, IMO.....Even a Blind Chickens gets the "odd" Kernel of Corn ?

IMO,
if you can't TELL the Machinist, HOW you want it done, I guess you are pretty much leaving it to him, and you GET, whatever he KNOWS about Performance Blueprinting ?

Same thing goes for supposedly "magical" Head Porters ?
Unless you are just staying with pretty basic "Pocket Port & Gasket Match" jobs, which really, ANY competent Knumbskull with a Die-Grinder can do......
and you DO NOT HAVE, or HAVE ACCESS TO a Flowbench, or, know how to use one, and READ the Data.....or NEVER DID know how ?
why,
would that someone undertake a "Full" Port Job for an unsuspecting Customer ?

No wars wanted, just stuff to think about....

I got no problem with Guys who want to access GOOD Machining/Blueprinting/Porting, and screw their OWN Engines together, those Guys usually have enough experience, and know enough about their OWN stuff, and smart, and KNOW at least "where" to go to get it.....
Rather,
It's the Guys that really know dunno SQUAT about Machining, or Head Porting, and start Building "Performance" Engines for Customers, then when something goes wrong, wanna BLAME the "Machinist" ?
Why the Machinist ?
THEY are the dimwit that screwed it Together.....did THEY not check it ?

I've seen it all over 35 years....
Guy comes in, giving my Counter Guy "Hell" because his Engine spun a Main ?
Never seen this Guy before in my Life ! Never did any work for him.....
But,
I guess we HAD "Machined" for his "Engine Builder.....
Seems his "Engine Builder", was blaming us ?
Long Story short....
got him to bring it in anyways, FOUND the problem....
seems dimwit put the Main Cap on BACKWARDS !
and,
we gotta listen to THAT ? and the "Stories" floating around for 6 months after.....

That changed our Business protocols....
We ONLY DO "Complete, Done, Assembled & DYNO'd" Engines, NO Exceptions...
or,
Machining Packages, ONLY for people who have come in and "trained" in procedure for 3 weeks in our Shop(usually the lead mechanic at whatever other Shop is using our Machine Pkgs)

[BSB67]

I don't know if anyone is making a 10:1 piston for the 383.  Do a cylinder pressure test, if you have not already.  The 750 DP would work nice IMO.

[71bee]

If you go with a 4150, make sure you take into consideration that you'll have a routing issue with your coil (if located in the stock position). i've helped allotta guys out by using a few brass elbows & 3/8" fuel line to get around this problem. also, some DP's only come with the PVC vacuum nipple in the rear of the carb. if your not worried about looking "stock," the DP will easily outperform an Edelbrock Performer.

[MoparMotel]

Got the new metering rods and springs put in Saturday night. I just took the car for a 50 mile drive about an hour ago, Car now does not stumble anymore and runs great!