Anyone here ever used 1.7 roller rockers on magnum heads? I am doin a magnum head swap on an LA block. I have most all the parts to do my rebuild. Speed pro .030 over pistons, balanced rotating assy, comp 480H cam. I need rockers and pushrods and I know the stock magnum rockers are 1.6. That would give me .512 lift. 1.7 rockers would give me 544 lift. Any thoughts?

Been using them forever. Bought mine for the same reason, wanted more lift without a cam change.

What kind are you using?

We are running the crower 1.7 rockers on the junkyard magnum truck. You will gain more area under the curve with the higher ratio. We picked up very little over the factory 1.6 rockers but they do look nice!

Any one run chivy or furd roller rockers?

You might want to remove the valve covers,
set up one dial indicator centered on the rocker arm tip directly over the center of the valve stem,
and another dial indicator on the other end of the rocker arm directly over the center of the push rod
and actually check what 'real world' ratio
your factory Magnum rocker arms truly are.

A few years ago Jesse Lackman of RevSearch posted here on Moparts that he did this and found that the actual ratio was closer to 1.7 than the 'nominal' 1.60 ratio.

In one of the three part "Magnum Manifesto" articles in Sept 1998 in Hot Rod Magazine they also list the factory Magnum rocker arm ratio as greater than 1.60

repost of what Lackman wrote back then:
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Jesse Lackman
Moparts Member
Posts: 395
From: Center, ND 58530
Registered: Jan 2000
posted 07-13-2002 05:16 PM
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how about 1.74?
Just measured one with a dial indicator. lobe lift at the rocker pushrod
socket = .345"

valve lift at retainer = .600"

Did it about four times to make sure

Jesse Lackman
Moparts Member
Posts: 395
From: Center, ND 58530
Registered: Jan 2000
posted 07-13-2002 10:52 PM
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I did check another one came up with a little less but still over 1.7.
Hughes has lots of roller cams for the magnum engines.


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boxcar
Moparts Member
Posts: 151
From: Mason MI USA
Registered: Mar 2001
posted 07-13-2002 10:07 PM
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Yeah, suprize! When I was degreeing in the cam in a magnum engine I got to
checking things and the ratio I got was around 1.69.

Made a cam lobe that was 270* seat, 218* @ .050 at the pushrod check at 224* @
.050 at the retainer. Makes you want to run out and spend $400.00 on some
heavily marketed roller rockers, NOT.

I dont have a full set of magnum rockers... I have looked at stock small block ford rockers and they are almost identical. I wonder if ford roller rockers would work?

I have a set of comp pro magnums on my 360. Used the crane stud conversion. Looks a little flimsy but they'll work for a hydraulic cam just fine. The studs that is, they look a bit on the flimsy side.

The aluminum (Viper) V10 rocker arms
will bolt up to 5.2/5.9 V8 Magnum cylinder heads;
but if you look carefully
you will see that the tip of this Viper V10 rocker arm
does not line up with the center of valve stem
and does not properly 'wipe' across the centerline
as the valve is lifted.

Again, checking for yourself with a pair of dial indicators
at push rod centerline and valve stem centerline
will show that the ratio is no longer a true 1.7
like it correctly is when on the aluminum V10 cylinder head it was designed for.