hi guys im new here but i have a wide array of knowledge on mopars /i have 10 years of racing experience and my dad has 30+ years of racing both of us in 440 big blocks one thing that baffles me now and i need some answers, now my fist rig a 1999 dodge ram 4x4 ex cab black sport 318 98k 3.55 gr mods were duel cat back, headers k/n intake, throttle body spacer not to much here but my problem was after holding her at 5200/hit rpm limiter were ever that is,just a few seconds trying to pass a slow tractor trailer the trans wouldnt shift from 2nd to 3rd i developed a huge lifter tick / dead cylinder was #7 driver side rear
now me and dad tore it down and after further investigation we found the LIFTER journal had cracked this rendered the whole block usless i was devastated and sold the truck! now my dad digs out a 1997 or 98 mopar muscle mag because he thought this occurance sounded familiar and it did!!!
they wrote that ALL magnum engines taken past 5200rpm can have this problem for the roller lifters are too heave causing bad valvetrain vibrations that can crack at the lifter journals! further more they wrote there is no way to solve this problem unless someone makes a lightweight roller lifter!

now i have seen a few in this forum mention going to 5500 rpms so now naturally i am stumped???

reson being i now have a 2001 dodge 4x4 ex cab 5.9 auto w65k which i scored for a mere $2600 for the trans is out in process of rebuild

thnks

 

i know you were passing someone but i wouldnt bring my truck to that high rpm at any time. the highest ive tached since ive had my truck is no more than 4grand. IMO its to harsh on thm, as you've come to find, and how my boss 318 came to find, and why he has a new built up 360 going in his truck. ive seen my boss blow his 318 by revving it up to 5200 rpms to get it to shift, and now the motor is gone.

 

Why would you want to go that high on the RPMs anyway? I have no power past 3500.

 

A Magnum, in stock or near stock form, will; not survive much past 5500 rpm. The combination of the crank, stroke, pistons, vavletrain just wont allow it. Not to be said that with certain engine mods that you can go to 5500 and beyond. But like Purple said, why would you? These engines were desgined to get a heavy truck moving from a stop. All your power and torque is made from off idle to about 3-4000 rpm. I tend to think of it as a big block, not super high reving, but power down low. Just my obsevation though.

 

that's crap,

The biggest limiting factor is the light seat pressure of the valve springs. Valve float happens when you get that high.

IDK how far you should push a magnum with a stock bottom end, but there are plenty of guys running stroker motors with forged bottoms ends to 6K+, if the lifter galley was a factor, a stroker motor still wouldn't be able to wind that high.

If that happened to your engine, it was either a cast flaw, or the valve springs started floating around and transferred valvetrain rattle down to the lifters.

 

I've never heard this...

The big limiting factor is the stock valvetrain, I start to float at 5600 RPMs. I take mine past 5k usually daily.

The bottom end is supposed to be really stout, there is a guy on the Dakota forums who was running with a 100 shot of nitrous on the stock bottom end to 6000+ RPMs without prblems

 

I think the problem is a combo of light valve springs and heavy hydraulic roller lifters.

There is no reason that the bottom end cant handle high revs. true, they stop making power around 4500rpm, but if you change the cam profile, intake/exhaust, and valve springs, I wouldnt hesitate to spin it to 6000rpm.

 

i would be more worried about the tranny shifting at that high of rpms...

what would be the highest you could go with harland sharps 1.7 without valve float ?

 

valve float RPM is dependant on valvetrain weight vs. valve spring pressure.

 

thanks guys now the main reason for my question is my 1987 ramcharger has a 1979 318 la or pre mag in it which my dad built its got 360 j heds bowl ported milled 20 tousands to bring comp back up milodon valves 2.02 in 160 ex m&p duel coil springs m&p cam 508lift high volume oil pump windage tray heddmen hedders m&p duel plane intake holler street avenger carb 670 cfm 3200 rpm huges stall converter
all with stock replacement internals such all the pistons and so forth
with this set up it makes nerly 390 hp at 6400 rpm on engine dyno not sure whats put to the ground though never had it dynoed installed it the truck

now i can do such a build with the 360 mag in my 01 1500 or are the new mags a totally different concept???