I have a '97 S-10 with a 2.2 engine and have been searching all of the net for info on installing 1.6 rocker arms onto my engine. I found this very comprehensive info and how-to over at J-Body.org and here's the link: http://www.ny-jbodies.org/library/en...2rockerarm.htm
GM 2.8L/ 3.1L 60 degree V6 ENGINES
GM 2.2L L4 ENGINES (97 –EARLIER ONLY)
WHERE DO I FIND ROLLER ROCKERS FOR MY ENGINE?
COMPETITION CAMS offers MAGNUM Roller Tip Rocker Arms. Available in a 1.52:1 ratio. Part #1413-12 and 1.6:1ratio. #1414-12 These rocker arms are a stiffer construction rocker arm that have a roller tip that Competition Cams claims a 10-30 hp increase over stock, -due to the increased stiffness and the reduced friction of the roller tip.
CRANE CAMS offers a full roller rocker. It is their GOLD RACE Extruded Narrow Body roller rocker. (For 60* v6 and center bolt v8 engines) it is an all aluminum needle bearing roller fulcrum and roller tip rocker. $$$ Very pricey. It is available in a 1.5:1 #25750-12 and 1.6:1 ratio #25759-12 but require cranes replacement nuts #99795 and studs #99148-12.
All part numbers are for the V6 engine, the –12 behind each number indicates quantity of 12. For the four cylinders purchasing two sets (24 rocker arms total) will work out to enough to do 3 engines, (8 rockers an engine) so if three people went together and bought two sets of rockers you will save some money.
WHAT EFFECT DOES A ROLLER ROCKER/DIFFERENT RATIO ROCKER HAVE?
With 1.5:1 or 1.52:1 ratio roller rockers the benefits are around 5 hp. due to reduced friction. With the 1.6:1 ratio rockers, you’re looking at more hp gain because the higher ratio acts like a bigger camshaft by opening the valve more. Thus allowing more air into the engine. Expect around 10-20hp. Remember be conservative these are estimated horsepower gains – depending on application power increases vary. Just because you swapped in these rockers does not guarantee that you gained 20hp.
The cam lift of the 95-97 cams is .288" the amount of valve lift for the different ratios are:
1.5 (stock)= 0.432" valve lift
1.52 = 0.4377" valve lift
1.6 = 0.4608" valve lift
Cam specs for a 92 3.1L
Lobe lift intake .2626"
Lobe lift exhaust .2732"
1.5 (stock)= .3939"int. .4098"exh.
1.52 = .3991"int. .4152"exh.
1.6 = .420"int. .437"exh.
To find valve lift from any cam when using different rocker arms take the known valve lift example .425" and divide by the rocker ratio 1.5. .425/1.5 = .283333333333 this is the cams lobe lift, then take the new ratio example 1.6 and multiply it by the lobe lift. .283"x 1.6 = .453" valve lift.
Valve lift – the amount the valve opens due to the combined lift of the cam and mechanical advantage of the rocker arm.
Camshaft lobe lift- the amount the camshaft lobe is raised up from its base circle.
WHAT ELSE DO I NEED?
If going with the Comp Cams rockers, The first thing you need to do for this swap is get a set of M10 rocker arm studs from a 2.8 v6, gm part number for these studs is #476530. These studs were sourced from an 89 2.8L Chevy celebrity. At my dealership (in Canada), they retail for $5.55 Canadian each. V6's will need 12, four cylinders will need 8 of them. The threads on these studs are M10x1.5x9.9/M10x1x18 these are a fully adjustable stud that were used on the v6s. These studs will compensate for the different ratio rocker. The stock rocker studs are non-adjustable and are a M10x1.5x9.9/M8x1x.32 the M8 non-adjustable stud will NOT work with these rockers. The Comp Cams rockers come with new 10mm nuts.
If using the Crane full roller rockers then you need to get cranes studs 99148-12 -which have a M10x1.5x9.9/ 3/8x24 stud. In addition, cranes nuts #99795. These studs use have the metric threaded end for the cylinder head and a standard type 3/8 stud/thread for the rocker arm. Don’t forget you can always check the wrecker’s for the GM studs used for the Comp rockers. I purchased six studs for six bucks from a local wrecker.
If installing the higher lift 1.6:1 rockers or installing an aftermarket performance cam along with any of the roller rockers you will also need a set of aftermarket high performance valve springs to accommodate the higher lift.
Comp Cams #’s 980-12 (springs) 742-12 (spring retainers) and 601-12 (valve locks)
Crane Cams #’s 99848-12 (springs) 99915-12 (spring retainers) and 99041-12 (valve locks)
These part numbers are for V6 engines only. However, with a little searching around, some after market replacements could be found for the L4. The stock springs for the L4 engine WILL work with the 1.6:1 rockers. There are a few companies said that these springs will be fine for that amount of lift on the 2.2L. New pushrods are a must, as the old pushrods and rockers have worn specifically to each other and using old pushrods with new rockers can cause premature wear along with voiding the warranty of the rocker arms from the company. Factory (stock type) pushrods will work fine.
*NOTE V6 owners. -Some of the earlier v6’s came with the adjustable M10 studs, some didn’t it depends on year. Check if your engine already is equipped with them before you go and buy a set to find out you didn’t need them.
If installing a set of 1.6 ratio rockers modifications to the pushrod guide plates will have to be made. As the pushrod angle is now altered and will sit closer to the guide plate. An angle grinder with a carbide bit is the easiest and quickest way to do this.
You must find top dead center (TDC) for piston number one. You can do this by removing the spark plug and by hand turning the engine over at the crank pulley until number one is at the top of the cylinder, use a screwdriver in the plug hole to feel the piston. While cranking the engine over pay attention to the rocker arms, if when the piston is moving up towards TDC and both rocker arms are not moving then the engine is on number one firing position if one of the rockers moves while coming up to TDC then the engine is on number four firing position, and needs to be cranked over one complete revolution.
ADJUSTMENT PROCEDURE FOR L4 ENGINES:
With number one piston on the firing position at TDC install the rockers on the studs, adjust the valves for number one cylinder only. Tighten in the adjusting nuts until all lash is removed. This can be determined by rotating the pushrod while turning in the adjusting nut. Once the play has been removed, turn in the adjusting nut one-half turn to center the lifter plunger. Repeat procedure for each cylinder one at a time while on the firing stroke only.
ADJUSTMENT PROCEDURE FOR V6 ENGINES:
With number one piston on the firing position at TDC install the rockers on the studs, the valves that can be adjusted are:
EXHAUST: 1, 2, 3
INTAKE: 1, 5, 6
Tighten in the adjusting nuts until all lash is removed. This can be determined by rotating the pushrod while turning in the adjusting nut. Once the play has been removed, turn in the adjusting nut one-half turn to center the lifter plunger. Now crank the engine over one complete revolution to number four firing position. These valves can now be adjusted:
EXHAUST: 4, 5, 6
INTAKE: 2, 3, 4