Figured I would post this for reference here. I took a picture of a 1.5(stock) ratio rocker and a 1.6 ratio rocker arm side-by-side the other night while I was installing a set in my 1993 GP. I get them from my junkyard for $30($28 + $2 or so w/ tax + an environmental fee they tack on), so I figured "why not?" even if it's only adding maybe 2hp(that's what desktop dyno says the max gain is, it's a pretty consistant 1-2hp gain in the upper rpms supposedly) to my naturally aspirated 3.1.
There are maybe 7-8 or more sets of these rocker arms left in the pull-a-part junkyard I go to if any of you guys are interested. I probably won't go back up there for a few more weeks though.
These rocker arms come from 1994 to 1995 year model cars equipped with 3100's. If your junkyard doesn't have years posted on the cars there, just look at the Vin #'s. The 10th digit will be "R"(1994) or "S"(1995) on the cars that have these rocker arms.
You will need to get the pushrod guide plates from the 94-95 3100 along w/ the rocker arms... also take the pivot balls w/ the rockers, but inspect them for any gouging, etc. beforehand. I ended up using my stock pivots because they appeared to be in slightly better shape despite having twice the mileage on them. The 3100 studs vs. our stock ones are slightly different(the threads on them are about 1/8'' longer, and they have extended tips on top of them. Our stock studs put the rocker arms in the same exact place as they would be in w/ the 3100 style studs.
Just another picture of the rockers installed in the front of my '93 GP.
EDIT: Here's a picture of a rocker arm stud from a 94-95 3100.
I also wanted to mention that I did some *VERY* crude measuring on these rockers and came up with approximately a 1.46 ratio for the stock ones and approximately a 1.57 ratio for the 94-95 rockers. It was a bit tough eyeballing measurements with a tape measure(I have some micrometers and calipers, just was too lazy to walk outside at this hour of the night/morning).
.
Here's a picture of how to measure rocker arm ratios I borrowed off of some random site.
http://i44.photobucket.com/albums/f14/platjblser/rocker_ratio.jpgEDIT(yet again): Just wanted to say that the installation on my car at least was practically free. I already had the blue "permadry" rubber Fel-Pro valve cover gaskets installed in my car(they're very durable and can be reused, just slather a small amount of rtv on the little tabs that go where the heads and lower intake mate up). I also used blue rtv to seal the front coolant pipe just to the left of the front valve cover. I would have bought a gasket for it, but rtv works just as well as long as you dry off the surface and clean it pretty well(I've had blue rtv there for the past 140,000 miles
).
Torque Specifications:
Rocker arm nuts - 18 ft-lbs
Rocker Arm studs - 47 ft-lbs(this is the specification for a 94-95 3100, the studs are identical in size to our 3.1 studs, so I used this specification and I'm 99% positive it's the proper specification for a 3.1 Gen II engine anyways. If you can, you can set your torque wrench to 47 ft-lbs before removing a stock stud and confirm the torque specification.)
Rocker arm cover(valve cover) bolts - 89 inch-lbs(key word here being
INCH)
