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. :laugh: 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). :laugh: .

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.jpg


EDIT(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)

Nice writeup Matt, I did this install on my TGP back in the spring. While I had it all apart I replaced the pushrods with Federal Mogul units. Only an extra $20 spent.

Excellent write-up and information! Thanks much Matt! :thumb:

So which ones have the roller tip?

Quote from: TGPilot on October 04, 2006, 11:19:15 PM
Excellent write-up and information! Thanks much Matt! :thumb:

So which ones have the roller tip?

Roller tipped rockers are aftermarket only(from Crane, I think they require the old 2.8 style studs and a little grinding on our pushrod guide plates in order to work).


I also forgot to mention in my initial post that the rocker arm nuts on our cars should be torqued to 18 ft-lbs.

from 1996 +, a full roller valve train was used. :icon_mrgreen:

Quote from: GPChief on October 05, 2006, 01:39:35 PM
from 1996 +, a full roller valve train was used. :icon_mrgreen:

Not entirely true. ;) Roller fulcrum rockers are used in 96+, not full "roller" rockers.

Thanks for the clarification!! ;)

Quote from: GPChief on October 06, 2006, 11:00:43 AM
Thanks for the clarification!! ;)

You're welcome. :cheers: BTW, which rockers are you running? I seem to remember you posting about 1.6's before...maybe the Crane or Comp roller tip ones?

I currently have the comp cams 1:6 in my TGP but I got a little happy with boost / low octane and my rings are shot (AKA when I hit boost my dipstick blows out of its holder) and it smokes like the dickins.  For the short time before I did major engine damage I noticed a good differance on the top end.

I recommend the 1:6 to all, as a matter of fact I'll be putting them in a TSTE that I got recently.  For ease of use I'd use the factory ones, adjusting the comp cams ones was a PITA.

I thought you had to change the guide plates when swapping to the 1.6 rockers.  Mine seemed like they were going to bottom out in the guide plate so I switch them to the 3X00 ones. 

Quote from: skalor on October 21, 2006, 10:50:51 PM
I thought you had to change the guide plates when swapping to the 1.6 rockers.  Mine seemed like they were going to bottom out in the guide plate so I switch them to the 3X00 ones. 

When I checked, my stock guide plates looked to have plenty of clearance. I will however pull the front cover off my '93 GP today to inspect the guide plates for any signs of rubbing now that I have ~500 miles on the rocker swap + multiple WOT runs. It only takes a minute or two to pull the front cover anyways. I'll update this post sometime today. I do have the 3100 guides laying around *if* needed.


EDIT: Ok, I checked the guide plates and they were indeed rubbing. They were touching the bottom just barely, but they were rubbing the sides of the guide plates pretty good(only on one side of the guide, I'll edit this again tomorrow with a picture or two). I had both sets of guide plates from the 3100's in my garage and had nothing planned today, so I went ahead and swapped the guide plates over on both cars. Live and learn I guess...and waste a good chunk of time in the process(took me right around 1.5hrs to swap them out on both cars, 30mins for the fronts on both cars...the other hour spent on the rears) . :laugh: Sooooo, grab the 3100 guides if you pick up these rockers. You *could* grind out the stock ones, but if you've already pulled the rocker arms from a junkyard, you might as well spend another 5 minutes and go ahead and get the proper guideplates along with them, they'll save you a lot of time grinding the stockers(you'll be there a while unless you have a air die grinder or something similar w/ a small carbide burr style bit). I swapped out the guide plates w/ both manifolds installed again...which makes it tough to access the rear bolts. For the typical DIY'er, you're going to want to go ahead and get both intakes out of the way so you have a clean angle of attack on the rear bolts. I updated my first post so that anyone reading will know to get the 3100 'plates now for sure.

Matt,

     Good info, I'll try and remember to take some pics of mine (ground out the old guides) when I get the old engine out.  I drove from TX to CO & other places so I've got about 2-3K on mine.

Thomas

damn i wish i would have read this thread before going to Colorado the other day.  on the way home from Kenny's shop i stopped by a j/y in Denver and picked up a set of 1.6 rockers from a '94 3100.  i got the rockers, pivots, and pushrods but didn't even think the guideplates would be needed :bash:  oh well, the whole set cost me $3.50 so i can't complain.  i wasn't even really planning on getting them until i spotted a '94 Corsica with the front valve cover removed.  initially i figured i'd just forget it since i didn't think i'd have time to get the rear rockers out before the place closed, but then i found a '94 Cutlass with the 3100 laying on the ground next to it.  so my front rockers are from a '94 Corsica and the rears are from a '94 Cutlass :laugh:  both engines were '94 L82s (with the black plastic valve covers) so i'm sure they are the same.

so which pushrods do i use?  i compared the '94 3100 pushrods to some pushrods i took out of a car with a GEN-II 3.1 that was all torn apart and either the intake or exhaust pushrod is longer than the other (can't remember which at the moment).  the other pushrod looked like it was the same length.

Josh,

   I used the same length pushrods, just upgraded to hardened ones.

HTH,
Thomas

cool, so i'll be fine just re-using the pushrods i have in my engine now?

i'm gonna have to see what the dealership charges for pushrod guideplates on Monday.  i don't want to tear into another 3100 just to get those ecspecially when the junkyards around here would probably charge me too much to be worth the hassle anyway.

i guess if anyone has some '94-'95 3100 pushrod guideplates laying around let me know.  i'm not going to grind mine up.

thanks for all the info everyone :)