Mopar Fueling Problem

[Arizona A-Body]

I am having troubles with my engine. I believe that it is a fueling issue but not competly convinced. I have a 1969 Barracuda with a built up 318. I am running a hot solid lift cam, worked 360 heads with proper springs for the cam, full length headers, MSD 6 HVC-L ignition system, Mallory Unilite, Accell 8mm wires, Holley 750 with vac secondarys etc etc. Here is the problem....I was running a Dual Plane LD4B intake on it and wanted to go to a single plane. I purchase an M1 and switched over. The engine was running well prior however I could feel the intakes limits after about 5 grand.

I switched the intake, plugs and wires only! I am still running the same carb, and everything else. The problem is that at about 3500 RPM my engine starts to stumbe and act life its starving for fuel. I thought that maybe my lod pump was not performing at its best so on went a 150lph electric and regulator. I have more than enough fuel to feed it now and it is still doing it.

I switched to a 600 Edelbrock that I used to run on the car and it still does it with the smaller carb at the same RPM.

I can't seem to find any vacum leaks or any other mechanical issues. Timing is good also.

Does anyone have any ideas or have they ran in to this before?

Thanks
Travis

 

[RedFish]

Plugs and wires may have created a problem ( chit happens ). There may be a rev limiter in the aftermarket ignition.That could have been the original problem. All speculation . Good luck

 

[rumblefish360]

RPM limited? What cam is in there?
A single plane intake should be good till 6,000 without batting an eye.

If fuel is an issue, start with a pressure gauge that you can see while driving.
A Carter street pump should feed a mild engine well. The strip pump is about as much pressure a carb can take,stock wise. I doubt it'll need a regulator.
The stock 5/16 line is also capable of feeding a decent engine.

 

[Arizona A-Body]

Thanks for the info. I have ran the engine to where it has problems with my head under the hood and I am holding 9-10 psi of fuel pressure with out fluctuation. I just pulled the intake to make sure that there were no vacum leaks around the gaskets also. I started it for the first time today in about a week and the problem seems to have gotten worse.

I am thinking that I may have a voltage regulator issue that is causing the problem. I notice that it is spiking badly and I am wandering if the is causing a shut down of the ignition box while I am driving......I am sure that I will figure it out sooner or later.

 

[Demon416]

Thanks for the info. I have ran the engine to where it has problems with my head under the hood and I am holding 9-10 psi of fuel pressure with out fluctuation.

I'd back off on that fuel pressure. Anything over 8psi and you'll have damage problems with the seats. Too much pressure will bend the floats up and constantly over fill the bowls. Just a thought.

 

[65barracudadude]

Welcome to the site!!!! The best A-body site that I can find on the web!!!!

 

[rumblefish360]

You need a pressure regulator if you do not allready have one. Start @ 6psi and work your way up if need be. 8 psi is high. Your flooding the carb. Very bad, fire hazzard!!!!!!!!

The voltage regulator should only run high for a moment after start up or in the case of a heavy draw made suddenly. Like a heavy bass note hit with other items working at the same time sudden;y, wiper lights signal all at once. Stock set ups do this.

A new regulator is needed by way of your description.

OH tea, welcome aboard.

 

[Demon416]

Oh yes, welcome to a great site.

 

[Arizona A-Body]

Thanks for all the help guys, I finaly got everything (fuel wise) working propoerly. I had a friend loan me a third carburetor and the problems all went away.......I have no idea whiy the first two were such problem children but what ever.

I only cranked up the fuel pressure as an experiment.....obviously that didn't help either.

I am still having voltage troubles. It drops to about 10 at idle and peaks to between 16 and 18 while driving. This causes all sorts of problems as I am sure you all can imagine.

I ave replaced most all of the charging system and I think that I may have a wiring issue in there. People have done some strange things to the electrical on theis car over the past 40 years.

Anyhow, thanks again!