Hemi Tunning, just doesn't gooooo!

[Mopar_Mudder]

Got the Hemi Cuda on the road for the first time today, was only 4 miles but it took 5-1/2 years to get there

Anyway the Hemi doesn't seem to be running up to what it should, dyno's at 490 hp. Idles real good but when you get into it feels like it is running out of gas or something, just doesn't through you back and go like it should, feels more like 300hp. It doesn't pop out the carb or back fire at all, just feels sluggish and rough. Same thing if you try and and go full throttle in neutral, boogs a little bit.

It is a 472 with P5153737 intake and Edlebrock 1406 carbs hooked up 1:1. Has standard Mopar electronic ignition with a stock repop coil.

Timing is at 10deg initial and 40 at 4500rpm. I detect no ping at any time.

Looking for ideas of where to start and look for. Might be something simple that someone can think of before I take half the car apart. The motor did sit for a year after being dyno's buy the engine builder. I will get ahold of him on Monday so see if he has any ideas.

[72cudamaan]

Run the throttle up in neutral. When it starts to bog spray a little fuel (gas or carb cleaner) in the throttle.
If the rpm's suddenly increase then you know your running out of fuel. Your all in at 40 seems a bit on the
high side and I would try 12 or so at idle.

[cudabob496]

ya, sounds like its not being fed properly.
I had similar situation when my Holley was jetted too small.
Or maybe not getting enough air?
float level?

[cudabob496]

when stand over carbs, and look down, do throttle plates
fully open when accel pedal on the floor?

[Chryco Psycho]

Check for WOT & make sure the carbs open all the way .
 I would disconnect the vacuum advance to the dist & leave it off you need about 16 * at idle & 36 * total advance , the 36* total is more important than the idle is .
Get back to us on how it runs after that

[Mopar_Mudder]

Check for WOT & make sure the carbs open all the way .
 I would disconnect the vacuum advance to the dist & leave it off you need about 16 * at idle & 36 * total advance , the 36* total is more important than the idle is .
Get back to us on how it runs after that

Throotle is full yes

On total advance ignore that number I posted for now. Bone head mistake and I never unhooked the vac advance when I took that number  guess I was in too big of a hurry to go for a drive

16 at idle, first I have heard that high. 36-38 total is what I normally shoot for.

[Oldschool]

Like Chryco said, set the full advance at about 36*. Don't worry about what it is at idle. Also check and make sure you have an adequate accelerator pump shot in the carbs.  Auto or stick tranny? Rear gears? 

[Mopar_Mudder]

Like Chryco said, set the full advance at about 36*. Don't worry about what it is at idle. Also check and make sure you have an adequate accelerator pump shot in the carbs.  Auto or stick tranny? Rear gears? 

Stick with 4:10's. I will have to play with the timming and see what it does, sounds like maybe that is the issue. This week is really busy, will be Sunday before I can get to it.

[Strawdawg]

so? how long ago was it on the dyno and have you changed anything since then?

[berna4406]

Here's my 2cents worth. I would pull off that intake and get the dual carb intake from Stage 5 or if you need extra clearance get the one from Arruzza High Performance. I had the same issue with a very mild 572 HEMI. Felt like it was not getting enough fuel. The problem was that the intake could not bring in enough air through a factory style intake. I talked with John Arruzza and told him what was going on. He set me up with a Stage 5 intake and a set of his modified carbs,he told me to be ready because this thing was gonna be a torque monster. He was right! This thing is a Beast!

You haven't said what heads your running or cam size, compression ratio but give John Arruzza a call he is pretty hard to get a hold of but I think that he will tell you to pull of that intake. Arruzza High Performance 919-918-7584
                                                                                                          Sam

[Mopar_Mudder]

It was dyno'd a year ago and nothing has changed other then me pulling the distributor to reprime it.

I am not going to do any intake or carb swapping. Want this to appear as stock as possible, I know I am giving up some performace doing that.

What is everyones feeling on the Orange ignition box, is their a better choice (staying with a stock box)

[Strawdawg]

It made enuf power on the dyno to run ok.   Seems to take you back to the distributor if the carb is not jellied up with old gas?

[Mopar_Mudder]

It made enuf power on the dyno to run ok.   Seems to take you back to the distributor if the carb is not jellied up with old gas?

Took the top of one carb before installing it in the car. The bowls were bone dry with no varnish or anything in them.

[Oldschool]

Took the top of one carb before installing it in the car. The bowls were bone dry with no varnish or anything in them.

Hey MM, That kinda relates back to my earlier post about the carb accelerator pumps. On the Edelbrocks, the accelerator pump "diaphragm" so to speak is made out of a leather or leather like material. If they ever get dry after they have been wet, they dry out and don't seal well at all against the pump well wall. Sounds like a combination of too much timing and too little pump shot. If that is the case, replace the accelerator pumps.

[Mopar_Mudder]

Hey MM, That kinda relates back to my earlier post about the carb accelerator pumps. On the Edelbrocks, the accelerator pump "diaphragm" so to speak is made out of a leather or leather like material. If they ever get dry after they have been wet, they dry out and don't seal well at all against the pump well wall. Sounds like a combination of too much timing and too little pump shot. If that is the case, replace the accelerator pumps.

I will check them out if timming doesn't do anything, thanks