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Installing Roller Rocker on a Chevrolet 4.3L V6


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Old 02-09-2008, 11:48 PM   #1
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The Basics :

There are 4 variations of rocker setups on the Chevrolet 4.3L V6. The difference is in the stud base and in the rocker adjustment and alignment. The first thing you must determine when starting this project is what variation you have. The first starts in 1988 and lasted until 1992. This setup uses a press in stud with a 10mm diameter and a rocker that is fully adjustable and NON self aligning. The second used the same stud but was a self aligning rocker arm. The third appeared on Vortec motors in the early 90's and also on some non Vortec motors and lasted until 1999. This setup uses a screw in stud with a 10mm base thread and a shouldered stud on top. The shoulder on the stud served as a stop on the adjusting nut. This setup is NON adjustable and is know as a Net Lash Rocker system. In 2000 and up model years GM introduced a roller rocker. This rocker sat on a guide plate and was bolted down with an 8mm bolt.

Key points in determining what rocker setup you have in your engine.
  • 1988 to 1992 all used press in studs, were NON self aligning and fully adjustable
  • 1992 to 1995 Vortecs ALL used a net lash system with screw in studs and self aligning rockers
  • 1992 to 1995 Tonawanda* Engines used a net lash system with screw in studs and self aligning rockers
  • 1992 to 1995 Romulus** Engines used press in studs and were full adjustable. The rockers were self aligning.
  • 1996 to 1999 All engines used a net lash system with screw in studs and self aligning rockers
  • 2000+ All engines used roller trunnion rockers. They were a net last system and self aligning.
* If it's a Tonawanda engine, it will have a "T" stamped on the machined surface on the block just in front of the right cylinder head.
**If it's a Romulus engine, it will have an "R" stamped on the machined surface on the block just in front of the right cylinder head.

1988 to 1992 with press in rocker studs, NON self aligning

On this type of engine you have basically one option. Remove the studs, drill and tap the head to accept a 7/16" rocker stud, install a 7/16" bottom X 3/8" top stud and use a set of narrow body rocker arms. This procedure should only be done with the heads off the block which makes it one of the most difficult procedures.

All the rockers below are NON Self aligning they will all require the use of push-rod guides.

Below are just a few of the rocker arms available.
Comp Rockers 1017-12, 1.5 ratio Aluminum
Comp Rockers 1018-12, 1.6 ratio Aluminum
Crane Cams 10750-12, 1.5 ratio Gold Race
Crane Cams 10759-12, 1.6 ratio Gold Race
Harland Sharp S1001, 1.5 ratio Aluminum
Harland Sharp S1002, 1.6 ratio Aluminum
Harland Sharp S1003, 1.65 ratio Aluminum
Scorpion SCP1037, 1.5 ratio Aluminum
Scorpion SCP1038, 1.6 ratio Aluminum

Below are some rocker stud options:

ARP #134-7101
7/16-14 Bottom X 3/8-24 Top

ARP #134-7104
7/16-14 Bottom X 3/8-24 Top ------- but a longer stud and a better option for full roller rockers.

1993 to 1995 with press in studs, Self aligning


Follow the same procedure as above except use self aligning rocker arms listed below
Crane Cams 10751-12 1.5 ratio Gold Race
Crane Cams 10758-12 1.6 ratio Gold Race
Comp Cams 1317-12 1.52 ratio Pro Magnum
Comp Cams 1318-12 1.6 ratio Pro Magnum
Comp Cams 1015-12 1.5 ratio Aluminum
Comp Cams 1016-12 1.6 ratio Aluminum
Scorpion SCP1073, 1.5 ratio Aluminum
Scorpion SCP1074, 1.6 ratio Aluminum

1993 to 1999
with screw in rocker studs


These engines used a 10mm rocker stud top and bottom. The one problem with this is the lack of any available conversion stud to work with a set of narrow body rocker arms. Do not use a 60* V6 conversion studs They have the right thread sizes top and bottom but they are too short. All narrow body rocker arms on the market come with a 3/8" stud hole. So your option is to tap the head with a 7/16"-14 tap and use a screw in stud similar to above. However the tap does not bite in very hard so it is advisable to coat the threads with JB weld prior to installing the studs. If you go this route use the stud options above and the rocker options below.


Anyone reading this article should do the community a favor. E-mail ARP (www.arp-bolts.com) asking them to produce a 10mm X 3/8" conversion stud that is long enough for use on a Vortec motor. The 60*V6 conversion stud would be perfect if it was 3/8" longer on top.


2000+ with factory roller rockers

This year of motor is very simple to do a roller rocker setup on. All parts can be purchased off the shelf and bolted in. This setup requires the use of a SELF Aligning rocker. The following are some of your options on rockers.

Below is an example of a self aligning tip. The "ears" keep the rocker tip on top of the valve stem. In a NON self aligning system this job is handled by pushrod guide plates.



Crane Cams 10751-12 1.5 ratio Gold Race
Crane Cams 10758-12 1.6 ratio Gold Race
Comp Cams 1317-12 1.52 ratio Pro Magnum
Comp Cams 1318-12 1.6 ratio Pro Magnum
Comp Cams 1015-12 1.5 ratio Aluminum
Comp Cams 1016-12 1.6 ratio Aluminum
Scorpion SCP1073, 1.5 ratio Aluminum
Scorpion SCP1074, 1.6 ratio Aluminum

All the above are self aligning rocker arms and will not require the use of guide plates. All will bolt on to your heads with the following rocker stud set

ARP# 134-7201 (16 pack) for heads with factory roller rocker M8x1.25 bottom 3/8-24 top


B 1.750
C 0.600
D 0.850
E 3/8-24
F M8X1.25

I would like to note one thing I did find a bit different.
The ARP conversion studs are part number 134-7201 as listed in this info. That is correct in that they are the right part number for the VORTEC heads. However that part is intended as a V8 setup and comes with the necessary 16 count studs. That's OK, but us V6 guys will have 4 left over.
ARP has since added part number 100-7201 which is the VORTEC V6-specific kit and has 12 count studs. That's the only difference. The price may vary tho in your search.

Also note that the rockers are in the same boat. For instance, CompCams #1318-12 are ProMagnums of 1.6 Ratio, Narrow, Self-Aligning and are in a count of 12 for a V6 application. But the CompCams 1318-16 are the exact same rocker, just in a 16 count for V8 applications.

The reason I make this a point is since the V8's are more common and thus the aftermarket parts are as well, it may be easier to find the V8 parts new and used than the V6 kits. This will broaden your search a great deal. Especially in the used search. Only thing is you have 4 left over. Ive noticed on the rockers, most places price the -12 and -16 kits the same. Yet fewer places carry the -12 kits.

Another note on these years. A LT1 motor had stock Narrow, Self-Aligning rockers. And Ive seen the aftermarket list kits specifically for LT1's. But they are the same as the late model Vortec's use in that they are a 3/8, self-align and narrow body.

Too add to that, LT4 motors came stock with a 1.6 ratio full roller rocker arm. Like the LT1 (1.5 ratio) the LT4 is a Narrow, Self-Align rocker with a 3/8 stud. So you may find a decent used LT4 set to add to your search. The LT4 rockers were made by CraneCams after their Race Series. Most have the bow-tie logo on the end. GMPP used to also sell them as well as a retro-kit for LT1 upgrades. I also read that the 'early' LT4 rockers had a recall and there is a 'late' kit. Check out some LT4/Vette sites for those part numbers and the TSB on that B4 you buy those.

Buying parts

These are not the only sources for aftermarket rockers. Cam Motion, GM Performance and others all offer options on rockers. If you wish to purchase other rockers you need to look for this type of description.

CHEVROLET 90 V-6 262 (4.3L) AND CHEVROLET V-8 88-99, 305 (5.0L)-350 (5.7L) CU.IN.

STANDARD STUD DIAMETER. NARROW BODY ROCKER ARM FOR USE WITH CENTER BOLT VALVE COVERS

The key points are 3/8" stud diameter and narrow body. If you find a rocker with these points then you can use them. Self aligning or NON Self aligning will depend on your engine.

Things to consider


When you have your valve covers off you should change your valve springs. When increasing lift beyond stock specifications it is and important to be sure they do not bind. Stock springs should be ok as far as coil bind goes but the fact that roller rockers will allow you to spin your engine faster means valve float will can occur. Valve springs are cheep insurance against a potentially catastrophic problem. I myself recommend beehive valve springs found on GM's LS series of engines. More about that can be found below.

Valve cover clearance will also be an issue. Any late model Vortec owners will have to switch back to metal valve covers found on engines before 1996.

When changing rockers hand rotate the engine by hand to ensure the pushrod does not touch any part of the head. This is especially important on early engines with NON self aligning rockers. Comp Cams P/N 4710 will allow you to elongate the pushrod slot if need be.

Installing Beehive Style Valve Springs on Chevy's 4.3L

In 1994 GM introduced the 3100 V6 engine. This engine used a beehive style valve spring. A beehive valve spring is narrower at the top than it is at the bottom. This design makes for a progressive spring rate that increases as the valve is open. This in turn provides better valve control. Later in 1997 GM introduced the LS1 V8 into the Corvette this engine was created with the same type of conical valve spring as the 3100 V6. As the Small Block progressed into the LS2, LS4, LS6 and finally the LS7 they were all created with the same style valve spring.

Below are specifications on the LS series of V8 engines the beehive springs were used on.

LS1, LS2, LS4 Valve Spring
Free Length = 52.9 mm2.08 in
Valve Spring Installed Height = 45.75 mm1.8 in
Valve Spring Pressure - Closed = 340 N at 45.75 mm76 lb at 1.8 in
Valve Spring Pressure - Open = 980 N at 33.55 mm220 lb at 1.32 in

LS6 Valve Spring
Free Length = 53.40 mm2.10 in
Valve Spring Installed Height = 45.75 mm1.8 in
Valve Spring Pressure - Closed = 400 N at 45.75 mm90 lb at 1.8 in
Valve Spring Pressure - Open 1= 150 N at 32.42 mm259 lb at 1.28 in

LS7 Valve Spring *Note: Do not use this spring it will not fit the Vortec motor. It is shown here for comparison sake only.
Free Length = 58.8 mm2.313 in
Valve Spring Installed Height = 49.75 mm1.959 in
Valve Spring Pressure - Closed = 450 N at 49.75 mm101 lb at 1.96 in
Valve Spring Pressure - Open = 1380 N at 34.75 mm310 lb at 1.37 in


Below are specifications on beehive springs offered by Comp Cams
26915
ODIDSeat PressureOpen PressureCoil BindRate (Lbs./In.)1.055/1.2900.660/0.885105@1.800293@1.2001.08531326918
ODIDSeat PressureOpen PressureCoil BindRate (Lbs./In.)1.055/1.2900.660/0.855130@1.800318@1.2001.085313

All of the above springs will fit the 4.3L Vortec spring seat perfectly. They all however will require a different retainer. You must use Comp Cams retainer number 787 this will give you the correct size retainer and also the correct install height. It will work with your stock locks.



Above : The retainer on the left is Comp's 787 retainer. The one on the right is a stock LS1 retainer. This retainer looks right but it will give you an install height that is far too low. Also your locks will not fit in the retainer correctly. DO NOT use it.

Below : The spring on the left is a stock LS6 spring. The one on the right is Comp's 26918 spring.
The Comp spring has a higher pressure than the stock LS6 spring.




Above is Comp Cams spring 26918 and retainer 787 installed on a 1997 4.3L Vortec.


When choosing a spring refer to your camshaft specifications. If you have a stock cam then use the GM LS6 spring or Comp spring 26915. Both of these springs will be very adequate for preventing any valve float at higher RPM's. They are also suggested for use when installing 1.6 ratio roller rockers.

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4.3l, 4.3l aftermarket rockers, 4.3l rockers, 4.3l springs, 4.3l vortec, specs


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