Difference in rocker arms? 2001 Vs 2003

[onefastV6]

I remember reading that the rocker arm stud changed in 2003 or something along those lines. Does this mean the rockers are different?

Also I have heads that are suposed to be off a 03, to take the rockers off I used a 5/16" socket. Casting # on the heads are 24507487 Can anyone confirm what year the heads are off of from the casting #?

Attached is a picture of the measurements of the stud that I took.



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[v6h.o.]

Yes they changed the bolt size from an M10 thread bolt - 10mm top nut. 2002 and previous style.
to the newer style which is a M8 thread (smaller sized bolt what you have there) with a 8mm top nut (8mm is the same a s 5/16ths in terms of socket sizes)

The rockers are obvously different due to the trunion bolt hole size to the corresponding bolt size.

[onefastV6]

Thanks, the reason I am asking is that I contacted ZZP about making us rocker arms that have higher ratio.

The e-mail I got back from Zoomer said " If you could send us a stock rocker with a note, that would be helpful"

Did anything else change other than the size of the stud on the rocker arms? I am going to go ahead and send one in to them, along with a note of the changes that were made between the different years.

[geoffinbc]

Nothing changed. They are still the same ratio.

[BlackJack]

do let me know if they come up with a 3400 specific hi-perf rocker, preferably needlebearing full roller.

[El_Diablo]

i thought we already had a pretty good ratio

[geoffinbc]

Well more would mean more lift and effective duration without a cam change. A little boost in performance for little effort.

[eliteweapons]

Any news on different ratio rockers yet?

[onefastV6]

Not yet, I just got back to school and haven't sent it out yet. I am heading to the post office tomorrow so I will see if I can't go ahead and send it out tomorrow. I also might contact intense as they currently have Harland Sharp making thier rockers in a 1.9 ratio.

[AaronGTR]

Not yet, I just got back to school and haven't sent it out yet. I am heading to the post office tomorrow so I will see if I can't go ahead and send it out tomorrow. I also might contact intense as they currently have Harland Sharp making thier rockers in a 1.9 ratio.

I wouldn't recommend that unless you make no progress with zzp.

[TheProfessor]

now im curious i know that higher ratio affects your not only your lift but also your duration but exactly how does it affect duration

[onefastV6]

Mathematically rockers do not change duration however in reality when tested with the proper tools they add a little duration. Normally the duration changes with rocker arms will be very minimal.