TT5.9mag
Two atmospheres are better than one
It’s the rings and the factory fuel injection that’s responsible.
What do you think about this statement.........
- Thread starter Brooks James
- Start date
-
WellI was going to say that but I didn't want to start a **** storm like the one over the actual 340 cam specs. Lol
They are better machined from the factory, however the cylinder walls on most I've machined couldn't go over .030 which I think isn't great but wear overall is better to start with.
That's just the few I've done. Any will need to be checked because some will go bigger.
Make my engines LA’s. Just sayin. You can’t compare wear between the two, oils have changed so much. Operating temperature has changed so much. Magnums have less internal friction, but any la engine can be built that way.
Ball stud/screw suck. Cheap *** shivvy production method. Mopar stamped steel shaft rockers are light weight and offer exceptional oiling characteristics.
The only time you run into trouble is when you run too high a lift cam and too stiff a spring to match it. Where that point is, I’m staying out of that argument.
I will say aluminum racing rockers work well on race cars that wear cycle race parts. They will eventually fail. Steel replacement rocker arms(cast) are the way to go on the street.
Ball stud/screw suck. Cheap *** shivvy production method. Mopar stamped steel shaft rockers are light weight and offer exceptional oiling characteristics.
The only time you run into trouble is when you run too high a lift cam and too stiff a spring to match it. Where that point is, I’m staying out of that argument.
I will say aluminum racing rockers work well on race cars that wear cycle race parts. They will eventually fail. Steel replacement rocker arms(cast) are the way to go on the street.
I'd also add to the machining process, the machinist himself is where quality comes from, not the machine itself. I use machines from a generation before mine. I set the clearances, make the crosshatch. Not the machine, I'm sure a CNC machine would do better and faster but it still takes the dude to plug in those numbers.
I guess I'm trying to say it's takes someone wanting to do it correctly on any machine
By the way, not too difficult to put LA heads on a Magnum. In fact, most 5.9 magnums up to '95 will have the oil hole to the cam bearing already there for the LA head oiling. Some 5.2's as well in the early years. IF not, you can either drill the block for the LA head oiling (if a guy wants to oil the LA heads like a LA engine)
I read awhile back, probably in Mopar Action that the reason for the switch to the pedestal type rocker arms was a concession to the AMC engineers that came over when Chrysler bought AMC.
Stock for stock, you can’t blame the newer engines for having some improvements over the old design. The oil pan and valve cover sealing is absolutely superior on a Magnum.
As Mentioned, EFI, low tension rings and computer controls resulted in a longer lasting, more powerful and reliable engine. The LA series never had those so when comparing stock for stock, the Magnum wins.
You could update an LA to Magnum levels of reliability just like you could with a slant six if you wanted. They just weren’t built that way when new. I think the improvements the Magnum had compare to what Chevy and Ford did to their engines. A Vortech 350 runs longer and cleaner than a 1975 350 too. Improvements in head flow, oil sealing and EFI over there too.
Stock for stock, you can’t blame the newer engines for having some improvements over the old design. The oil pan and valve cover sealing is absolutely superior on a Magnum.
As Mentioned, EFI, low tension rings and computer controls resulted in a longer lasting, more powerful and reliable engine. The LA series never had those so when comparing stock for stock, the Magnum wins.
You could update an LA to Magnum levels of reliability just like you could with a slant six if you wanted. They just weren’t built that way when new. I think the improvements the Magnum had compare to what Chevy and Ford did to their engines. A Vortech 350 runs longer and cleaner than a 1975 350 too. Improvements in head flow, oil sealing and EFI over there too.
I've seen a 5.9 in a Van in the local area that had 435k miles on it, long block never taken apart. Couple timing sets, water pumps, starters, but nothing internal. My 5.9 just turned 322k this week 
I totally understand somebody preferring the LA's. I too, like the rocker shafts. But, it's just pure prejudice to say magnums aren't good engines. And the magnums have absolutely proven on the drag strip they can perform with any LA.
I totally understand somebody preferring the LA's. I too, like the rocker shafts. But, it's just pure prejudice to say magnums aren't good engines. And the magnums have absolutely proven on the drag strip they can perform with any LA.
Last edited:
TT5.9mag
Two atmospheres are better than one
I’ll add a cam and springs to your list as well. That really wakes up a 5.9.
It was either Hot rod or Car Craft that took a Dakota R/T 5.9 and added a bunch of Mopar approved parts and despite spending thousands of dollars on headers and other emission legal stuff, the efforts produced very little improvements. They were limited by the computer and it’s programming.
I believe the question I was answering was,
“What part of the magnum was superior stock???”
“The efi system is not that great.”
Somewhat true but, you get a block that has good cylinders
“The camshaft is weak weeny”
True, but did most LA come stock with much better, and provisions in the M block make roller lifters easier come cam swap time, you know you’re gonna swap cams anyway.
“The cylinder heads don't flow worth a crap and can't be ported to support real HP 550 or greater.”
Which are we talking about stock or not, I forget, but the statement did say stock.
“Chamber design okay, chamber actually junk they all crack between the seats.”
True,
“They are untunable without someone else building a tune for you.”
True, because of the EFI I suppose, but you did say stock, so I would say that there are more EFI engines running pretty good with 100K+. Back in the day someone was some kind of god if they had a car with over 100K, and they certainly didn’t have cylinders with hone marks if they did.
If you wanted to do a real cam swap there is 1 or 2 very expensive options for adjustable rockers
My reply was based on the thread it was originally and incorrectly on.
I've owned plenty of magnum powered vehicles and other la or big block vehicles.
Magnum is not impressive or in my opinion superior in stock from.
TT5.9mag
Two atmospheres are better than one
I’d bet “production” machining is no longer a guy plugging in numbers. As the machines get better they get more accurate, and need less involvement from a guy.
Anyone remember the thread where some dude wanted to bore and hone a block with a mag drill?
I'm not sure anyone said it can't be tuned.
Yeah there's flyin Ryan and HP but besides that unless you're a wizard you have to pay someone and rely on them to answer the phone if you run into an issue.
I guess that's okay for guys who can't be efficient with a carburetor.
Don't get me wrong the magnum is fine but really it's not superior with all of its issues that come with it. I still have a r/t Dakota and 1500 and they're just fine for what they are.
I think to answer the OP's question .... yes, the magnums can spin to 6500 with stock rockers
LA vs Magnum =
Junk and Junkyard dog fight Gggrrrrrrrrr
Magnums!!
LA vs Magnum =
Junk and Junkyard dog fight GggrrrrrrrrrMagnums!!
Anybody who can turn a computer on and make it work is a wizard to me lolIt doesn’t really take a wizard. It takes some effort though. About the same amount as most people won’t invest in tuning a carburetor.
Richard Holdener dynos a stock 360 with 4bbl and headers and makes 277 hp and a 5.9l with 4bbl and headers dynos 301 hp, and there is a manifold and header shootout and the 5.9l dynos as high as 327 hp.
He also dynos a 212 roller in a 5.9l for 350hp, and xe250h with a mild ported 2.02 head to the 360 for 350 hp then goes up to a xe268h for like 380hp.
And the 380 crate 5.9l dynos 400-410 hp imagine a similar cammed 360 would do high 300 hp. In stock from the magnum seem to respond a little better to a cam swaps.
He also dynos a 212 roller in a 5.9l for 350hp, and xe250h with a mild ported 2.02 head to the 360 for 350 hp then goes up to a xe268h for like 380hp.
And the 380 crate 5.9l dynos 400-410 hp imagine a similar cammed 360 would do high 300 hp. In stock from the magnum seem to respond a little better to a cam swaps.
Yeah you're probably right. I'm sure you are
Just not a bone stock factory delivered magnumI think to answer the OP's question .... yes, the magnums can spin to 6500 with stock rockers
LA vs Magnum =
TT5.9mag
Two atmospheres are better than one
Interesting. I have not had similar results. My LA stuff has always liked 36-37 degrees for max power. My magnum likes 32-33. Is that enough of a difference to quantify “more efficient”, hell who knows. But it is consistent, at least in my experience.
-
