Moparts
440 breaking up at 5500rpm
Posted By: tywebb2
440 breaking up at 5500rpm - 10/03/13 01:05 AM
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?
Posted By: Hot 340
Re: 440 breaking up at 5500rpm - 10/03/13 01:08 AM
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.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/03/13 01:40 AM
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.
Posted By: Hot 340
Re: 440 breaking up at 5500rpm - 10/03/13 02:01 AM
Quote:
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.
its probably neither of those then...I had a wore out factory distributor that did that. Might be your msd box going bad?
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/03/13 02:37 AM
Kind of odd how the problem showed up right after the cam swap?
Posted By: goldmember
Re: 440 breaking up at 5500rpm - 10/03/13 03:29 AM
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.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/03/13 04:16 AM
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?
Posted By: Defbob
Re: 440 breaking up at 5500rpm - 10/03/13 05:13 AM
Low voltage to ignition leading to poor spark? How does the ground wire to the block look?
Posted By: goldmember
Re: 440 breaking up at 5500rpm - 10/03/13 05:35 AM
Quote:
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? [/quote) I'd pull at least 1 and check it. Are the springs new?
Posted By: Mr.Yuck
Re: 440 breaking up at 5500rpm - 10/03/13 01:23 PM
Valve springs I'd guess.
Posted By: 383man
Re: 440 breaking up at 5500rpm - 10/03/13 02:45 PM
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
Posted By: dogdays
Re: 440 breaking up at 5500rpm - 10/03/13 03:42 PM
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.
Posted By: Harley
Re: 440 breaking up at 5500rpm - 10/03/13 07:33 PM
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.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/04/13 02:04 AM
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).
Posted By: Sport440
Re: 440 breaking up at 5500rpm - 10/04/13 02:31 AM
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#
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/04/13 02:53 AM
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?
Posted By: Sport440
Re: 440 breaking up at 5500rpm - 10/04/13 03:28 AM
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.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/04/13 04:11 AM
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?
Posted By: Cab_Burge
Re: 440 breaking up at 5500rpm - 10/04/13 07:59 AM
Quote:
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?
No 
You want the lifters full of oil and pump up just like the motor will be ran at I prime all my hydraulic cam motors while turning the motor over by the starter or by hand on the engine stand with the spark plugs out before setting the lifter preload I also recheck and reset as needed after breaking in the cam and lifters, I like and use 1/5 to 1/4 turn of preload when hot 
Posted By: Dodgem
Re: 440 breaking up at 5500rpm - 10/04/13 01:44 PM
Maybe you have much more pre load on some then you think?
Posted By: B3RE
Re: 440 breaking up at 5500rpm - 10/04/13 06:46 PM
I guarantee if you put springs with 580# open and 230# seat you will get rid of the valve float and even wear some of that aggressiveness off of the lobes.
Seriously though, I know what the problem is because I have experienced it. Find a way to raise the rocker shaft .250", yes I said 1/4", and the problem will go away. Let me know if you need assistance with this and I can help. Your springs are not too heavy, but I don't think they are too light either, IF the rocker shaft is at the right place. Logic would tell you if the only thing you changed was the cam, then the first place to look for a problem is in the valvetrain.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/05/13 04:51 AM
Well I installed new plugs and backed the preload off another 1/4 turn. Hopefully that will do the trick? Will know tomorrow morning when I take it out for a test run. If this doesnt work then I will be pulling a couple springs and having them checked.
Cant say I have ever heard of raising rocker shaft 1/4"? What is the theory behind doing that?
I dont have a crank trigger.
Posted By: rickraw
Re: 440 breaking up at 5500rpm - 10/05/13 05:38 AM
If u raised them that high, i think, no, i know u will have a bigger problem.
Posted By: goldmember
Re: 440 breaking up at 5500rpm - 10/05/13 06:12 AM
Quote:
Well I installed new plugs and backed the preload off another 1/4 turn. Hopefully that will do the trick? Will know tomorrow morning when I take it out for a test run. If this doesnt work then I will be pulling a couple springs and having them checked.
Cant say I have ever heard of raising rocker shaft 1/4"? What is the theory behind doing that?
I dont have a crank trigger.
It's the springs combined with the cam. They work fine with the old MP cam but not with the new .904 lifter stuff,no suprise really. Another option would be replace the cam again.8yr old valve springs? LOL Get a few checked and go from there.
Posted By: Cab_Burge
Re: 440 breaking up at 5500rpm - 10/05/13 07:01 AM
I like to set the seat pressures from 140 to 175 lbs on the seats and from 325 to 375 lbs opened on all of the agressive lobed cams with either hydraulic or solid fat tappet lifters. Maybe a little more with the really good lifters like the tool steel or the Shubeck type ceramic puck bottomed lifters
Posted By: B3RE
Re: 440 breaking up at 5500rpm - 10/05/13 01:11 PM
Quote:
If u raised them that high, i think, no, i know u will have a bigger problem.
I am not making a wild guess here. Based on his valve lift and the type of rocker he has, it will get him in the ballpark at .250". I use math formulas to arrive at my conclusions, not just guesses or what I think might help. I can confidently stand behind my advice.
Posted By: B3RE
Re: 440 breaking up at 5500rpm - 10/05/13 01:34 PM
Quote:
Cant say I have ever heard of raising rocker shaft 1/4"? What is the theory behind doing that.
Roller rockers have different geometry than factory rockers do so the geometry is thrown out of wack when they are used. Your combination is very close to one I corrected geometry on and the car pulled for another 800 rpm. I couldn't say how much of an improvement you will see, but I will guarantee an improvement. The only reason you didn't have an issue with the 509, is because the lobes are so much slower than your current cam (roughly the same lift with 20 deg less duration). I have explained more in other threads. Just search rocker geometry or B3RE.
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/05/13 03:24 PM
Well....1/4 turn less preload and I it is still breaking up as most of you guys predicted. I want to say it wasn't quite as bad a previously but that may be splitting hairs. It is still breaking up at around 5700rpm.
Guess the next step will be to pull a couple springs and have them checked next week. Will have to do a little more research on raising the rocker shafts. My combo is fairly mild with the OOTB Eddy heads, comp pro mag rockers, 10:1, and the Lunati 630303 hyd cam. I thought Comp designed the rockers for install without any major modifications?
As far as it being an issue on the electrical side...it could be possible but I think it is just strange how the car ran fine with the 509 cam and after only swapping the cam this problem showed up. The distributor cap looks good and clean, new plugs installed, and tried a different chip in the MSD box. All leads me to want to go after the valvetrain first.
Posted By: Dodgem
Re: 440 breaking up at 5500rpm - 10/05/13 04:40 PM
take another 1/2 turn out and try that first! a little ticking won't hurt anything!
Posted By: tywebb2
Re: 440 breaking up at 5500rpm - 10/05/13 05:10 PM
I should only have 1/4 turn preload on them now...at least that is what it should be. I guess I could go through and start over finding "0" lash and then put 1/8 turn on them...and see what happens.
Posted By: Dodgem
Re: 440 breaking up at 5500rpm - 10/05/13 05:45 PM
Lashing hydraulic cams is very tricky. try backing off 1/2 turn just to see what it does before re setting.
Posted By: BRONZEBEE
Re: 440 breaking up at 5500rpm - 10/07/13 04:46 PM
I think I would try checking my timing first
Posted By: Digger73
Re: 440 breaking up at 5500rpm - 10/07/13 05:29 PM
Dist rotor phasing?
Digger73
Posted By: maximum entropy
Re: 440 breaking up at 5500rpm - 10/08/13 06:09 PM
check the underside of the air filter lid for evidence of reversion. i had this exact same problem, and my air cleaner lid was literally dripping with fuel from reversion. a carb spacer (to in crease plenum volume) took care of the problem. i also had some exhaust restriction, which compounded the problem.
Posted By: RobX4406
Re: 440 breaking up at 5500rpm - 10/08/13 06:35 PM
I'd bet that engine is done making power at 5200ish
Posted By: RATKLR
Re: 440 breaking up at 5500rpm - 10/09/13 05:48 PM
Can't say how many times we had to replace plugs or plug wires after doing a cam break-in. All that heat with a car that's not moving is pretty hard on the boots.
Also, that cam seems somewhat smaller than the 509, but I don't know if that's what your intention was.
Posted By: B3RE
Re: 440 breaking up at 5500rpm - 10/12/13 03:04 AM
Quote:
I'd bet that engine is done making power at 5200ish
Not with good heads and that cam. With stockers and a generic cam I would agree.