Magnum Head Rocker Arms

-
bobscuda67

bobscuda67

Well-Known Member
Joined
Aug 27, 2005
Messages
2,138
Reaction score
401
Location
Michigan
Hey All!
I'm using Chevy style 1.6 Crane rockers on my magnum heads and they seem to be working ok except for the valvetrain noise. Sounds like it has a solid cam with all the ticking.
I was wondering if anyone ever looked at the issues to install a small block Ford shaft system on a magnum head. It looks like it's worth looking into from some of the pictures I've seen.
We need a cheaper alternative to Hughes shaft system.
 
My magnum has a noisy ish valve train/lifter sound too, which I’ve heard is common on these. Nothing major though, you just hear it. Sounds kinda like big block valvetrain.
 
Hey Bobscuda,

I'm not sure if this is relevant to your post but I also ran into valve train ticking noise on my Magnum Stroker.

Fully balanced and blueprinted motor , Edlebrock Aluminum heads, Scorpion Racing 1.6 rocker assy, high pressure oil pump, custom length pushrods, Mopar Performance lifters.

I broke in the engine on Brad Penn oil (Yeah. I know I didn't need to) and no perceptible valve train noise until I drained the oil after approx. 1000 miles and installed a 5w30 synthetic oil.
Valvetrain became as noisy as hell after about 10 miles, so bad, I thought it was rod knock.

Changed out what I thought was a bad lifter (Used a stethoscope to isolate it). Put it all back together , now a different lifter in the other cylinder head doing the same thing!

Out of desperation, and from suggestions from an engine builder, I changed the oil to non synthetic Castrol 5w 30.

Voila! Noise gone but I could not find an explanation for this.

Until a Mobil Oil rep came into our Garage and informed me that the oil I used was specific to Mercedes Benz engines only ( BTW, it says so right on the bottle).

I then switched back to Royal Purple synthetic and no issues since.

Bottom line for me was I need to start reading product labels and stop assuming ****.

I learned this the hard way and it cost me 3 oil and filter changes plus the lifter and the head, intake and valve cover gaskets. (couldn't get the lifter out of the galley without removing the cylinder head).

Hope the lesson I learned the hard expensive way helps someone else.

Cheers!
 
Ever thought about running stock magnum rockers? Because of rules I had to run them, never ever had a problem with them. Put Chevy rockers on 1 motor and can’t complain but didn’t see any difference, not sure about noise, we ran open headers on all of these motors.
 
As far as oil I use 20w50 Valvoline so that shouldn't be an issue.
And I have thought about going to stock parts but I wanted to make sure the 1.6 ratio is accurate.
I really doubt the stock rocker is a 1.6 ratio but it's reliable and quiet.
What I should have done is go 2 steps bigger am and used the the stock rockers. But now finding Mopar rockers is not easy because the market is flooded with knockoffs.
 
bobscuda67 said:
As far as oil I use 20w50 Valvoline so that shouldn't be an issue.
And I have thought about going to stock parts but I wanted to make sure the 1.6 ratio is accurate.
I really doubt the stock rocker is a 1.6 ratio but it's reliable and quiet.
What I should have done is go 2 steps bigger am and used the the stock rockers. But now finding Mopar rockers is not easy because the market is flooded with knockoffs.
Click to expand...
Magnum with roller cam uses 1.6 rocker ratio. Rockers are available from many retailers
 
JunkyJimmy said:
Ever thought about running stock magnum rockers? Because of rules I had to run them, never ever had a problem with them. Put Chevy rockers on 1 motor and can’t complain but didn’t see any difference, not sure about noise, we ran open headers on all of these motors.
Click to expand...
The guys at magnumswap.com
Regularly spin stock magnum rockers to 6500, no issues with valve train
with appropriate springs, of course
 
A magnum rocker will yield 1.6 or better at the retainer, shim up a lifter solid and check with a dial indicator, even with pushrod angle and all. The only thing I had trouble with was the factory pushrod, they would bend at low 6000 with a 325 spring and 550 or so lift. I’m sure the lobe configuration could move this up or down. A simple set of aftermarket pushrods always solved the problem.
The rage on the Ram pickup forum is to put a set of 1.7 high dollar rockers on your stock truck, I really wonder if the juice is worth the squeeze on that, I honestly doubt it but I may be wrong.
 
I agree with Junky, the factory rockers are actually really good. I tried a set of chubby rockers and could not get the geometry correct. Lost lift due to it. If running a chubby rocker, 1.65 ratio is needed to yield the 1.6 on a Mag.
 
408 swinger said:
I agree with Junky, the factory rockers are actually really good. I tried a set of chubby rockers and could not get the geometry correct. Lost lift due to it. If running a chubby rocker, 1.65 ratio is needed to yield the 1.6 on a Mag.
Click to expand...
I had read sometime back that a guy had a problem with Chevy rockers on a magnum. He stated that he solved the problem using Oldsmobile guide plates
 
I've got PRW rockers (1.65 ratio) with Rhodes lifters on my Magnum headed LA and it's pretty quiet in the valve train. I use 10w-30 VR1 oil as well. I've got another Magnum with stock rockers and some cheap lifters (they're from 2015 when you could actually get ones that wouldn't die in 10 minutes) and it sounds like a sewing machine. I've often thought pushrod length could be causing the issue, but I'd be willing to bet it's just the quality of the lifter. Honestly every Magnum I've ever had has some valve train noise it seems, but not enough for me to ever be concerned with it.
 
The Chevy rockers I used were comps, needed studs, guide plates, hardened pushrods, didn’t really get that warm fuzzy feeling doing all that. I never did check the actual ratio on them, I still have the motor, maybe this winter I should take a look at that.
 
Brooks James said:
I had read sometime back that a guy had a problem with Chevy rockers on a magnum. He stated that he solved the problem using Oldsmobile guide plates
Click to expand...
Oldsmobile studs. They have the 5/16 thread for the head and 3/8 for the rocker. I think we had Magnum guide plates.
 
My Magnum headed LA motor is pretty quiet. I believe some peoples issues might be too short of a pushrod causing the preload on the lifter to be too light. Just my 2 cents.
 
I used the Crane 1.6 rockers so I could have an adjustable valve train. And I never checked to see the lift at the retainer either.
I always thought that the stamped stock rockers were less than the rated ratio, the same way the LA rockers were.
 
Are the oil holes in the lifters all pointed towards the valley? If not they will tend to bleed down and be loud.
 
It's probably the lifter preload... Magnum rollers aren't like your typical flat-tappet hydraulics, they like .080"+ preload or they will be noisy. I have a 150k+ mile 5.9L Magnum short block with stock lifters and stock LA rockers (long story) on a custom-grind Racer Brown cam and the valvetrain is not much louder than stock. It's got at least 15k miles on it since I put it in my Duster. Had to get custom-length pushrods when I put it together to get the right lifter preload.
 
You must log in or register to reply here.
-

Back
Top