I recently swapped cams in my 440 from the MP 509 hyd to the Lunati 60303 (.494/.513, 268/276, 226/234 @.050"). I finally got to the point last weekend where I opened the car up for a WOT pull while tuning the carb and noticed that when I get up to 5500-5700rpm the car starts breaking up like it has hit the rev limiter.

I tried a different carb this past weekend and there was no difference. I tried a different chip in my MSD box thinking the one in there may have went bad but still no difference. The AFR meter is reading around 13.0 at the leanest point so it isn't running out of gas. As soon as I shift from 1st to 2nd or 2nd to 3rd the car stops breaking up and starts pulling hard again which to me means it has enough fuel as well. I also never had any fuel supply issues with the 509 cam.

Could this be as simple as a bad plug, plug wire, or distributor cap? Other than that I am thinking valve springs but I have the ootb eddy springs on their heads that are rated for up to .600 lift. I never had an issue with them when using the 509 cam?

Check lash/preload, if running non adjustable rockers on a hydraulic cam, the base circle mite be different on new cam. Also, check distributor wobble as well. Damhik.

I am using comp pro mag adjustable rockers. I had 3/4 turn preload on them and tried taking a quarter turn out but it didn't make a difference.

I have an MSD distributor. When you mention wobble do you mean the cap being loose or he rotor actually wobbling? The cap bolts down and is very secure.

Kind of odd how the problem showed up right after the cam swap?

Valve train going whacko is my . Need the correct valve springs and installation. JWAG 135lbs seat and 325lbs open should work,less seat lbs would NOT likely be happy,check yours and see what you have.

That is kind of what i was afraid of. What do you think the open and seat pressures are for the eddy valve springs are? They list on their website that they are rated for up to 600 lift but nothing about the open and seat pressures?

Low voltage to ignition leading to poor spark? How does the ground wire to the block look?

Valve springs I'd guess.

I remember some years back we ran my buddies 383 Cuda which was a 68 and it had Comp valve springs that were old. It started breaking up around 6200 just as it went thru the traps. But it still ran 11.40's @ 118. It would break up just as you went past the stripe. It ended up being weak valve springs. That said we ran the Eddy RPM heads on my sons Dart with their stock single spring for 3 years like that and it ran fine running a best of 11.55. How old are the springs on your Eddy heads. Ron

Your problem is classic, valve springs incorrect for the cam. The Voodoo cam line, as well as the Comp XEHL line, and all of the Hughes cams, use very high lifter acceleration rates that require matched springs for success. The cam manufacturer is the one to ask about springs.

R.

I had a similar problem to what you are describing. I changed the cap and rotor and it went away. The old cap and rotor looked fine, but the new one made all the difference.

I talked to Lunati tech this evening and they seemed to think it could be too much preload...lifters pumping up at high rpm and not allowing the valves to close. They suggested taking a quarter turn out and trying them at only 1/4 turn preload. If that doesnt work then look at the springs. Said I should have 120 seat and 320 open. Safe range would be 100-120 seat and 300-325 open.

I did pull my distributor cap and cleaned that up and bought a new set of plugs to throw in it too (autolite 3924).

Thats a good test with the lifter preload.

I dont know how worn your Eddie springs are, but New, Dwayne Porter measured a set compared to some Hughes springs I was using and got

1.900-127#
1.860-140#
1.400-297#
1.300-330#

My heads/springs are probably about 8 years old with very low mileage on them.

I just found eddy specs on the springs.

115# seat
280# open at .500"

Of course I need to check one to verify but looking at the factory spec would that mean I don't have enough pressure on the open?

The specs I posted above are for New Eddie springs, those numbers would be fine with your new cam.

My Eddie Spec sheet that came with my heads show a 120# seat at 1.88

With your 8 year old heads, your springs may be on the worn side. A spring test is in order for sure, but they may still be in range with what Lunati stated.

I wonder if I should pull the intake and all lifters so I can bleed them down and start from scratch setting lifter preload. I went back in and reset it after the initial break in (which I now know was a mistake). Setting the preload with the intake on makes it a little more tricky and I know some of the lifters were pumped up which is bad too...right?

Maybe you have much more pre load on some then you think?