Opel GT Forum banner

1 - 13 of 13 Posts

·
Super Moderator
Joined
·
13,622 Posts
Discussion Starter #1
An inexpensive substitute for the hard-to-get Opel locking rocker arm nuts is the locknut from a 2.8 litre, 60 degree Chevy V6. They're the correct metric thread, 10 mm x 1.00, and they are more readily available, cheaper by far, and they seem to hold their locking capability longer. I've run them over 60,000 miles with ZERO adjustments.

One word of warning, they do not have a base flange like the Opel nuts, so if you have a reground performance cam with a smaller base circle than standard, they MAY bottom out on the shank of the rocker stud. If this is the case, use 7/16" HARDENED flat washers to shim the lock nuts up (above the rocker pivot ball). Do NOT use regular washers, they will get destroyed and allow metal into your engine!

Bob Legere
 

·
Moderator
Joined
·
1,973 Posts
how can I tell if I would have the problem with the smaller base circle? Im using a .416" lift 270 duration solid lifter cam. So I would think that just the nuts would be fine without the washers.
 

·
Super Moderator
Joined
·
13,622 Posts
Discussion Starter #3
If the nuts bottom out on the stud before you have reached your adjustment, then the cam has a smaller base circle.
 

·
Old Opeler
Joined
·
5,564 Posts
Rocker Studs

Another neat item for the 60 degree V6 is the rocker studs that come with the Crane Roller Rocker kits. 10mm on the bottom and 3/8" on the top for use with Chevy rocker lockers. They need a hole drilled up through them for oiling the rocker balls - but I have just figured out that the grubscrew in the rocker locker can have a metering hole drilled in it so that no hole needs to be drlled through the side of the stud ( like Opels do have them).
The studs may have to have some mods done to the hex area to fit under Opel rockers but they are made by ARP and thus are of excellent quality.
Part # 99148-2
 

·
Moderator
Joined
·
1,973 Posts
how do I initially put the nuts on so they arent way too tight or too loose before I adjust them becuase I guess im going to try to do it running.
 

·
Member 1000 Post Club
Joined
·
1,520 Posts
Jordan,

I just went threw the process of degreeing in a new cam for my rebuild. The short story of what I learned is that I would not adjust the lifters with the engine running. I found that if they are not adjusted the same for each cam lobe, they effective duration of each cam lobe will be different. If you are using hydraulic lifters, the adjustment method described in the FSM is very straight forward, "One full turn clockwise from zero clearance".

HTH
 

·
Moderator
Joined
·
1,973 Posts
I went to napa to pick up the 2.8l rocker arm nuts and they are the wrong ones, did they change with different years? these were too small.
 

·
Super Moderator
Joined
·
5,808 Posts
To bump this thread, what are the details of the required Chevy 2.8 rocker nuts? Is there a specific year that fits?
 

·
Old Opeler
Joined
·
5,564 Posts
All Metric

Keith, As far as I know the 60 degree Chevy 2.8 L V6 was designed as a "metric" motor - the only thing I can think of is that Jordan got 3/8" nuts off a 90 degree Chevy V6 (a completely different motor).
 

·
Moderator
Joined
·
1,973 Posts
that is what ended up happening at napa, carquest said they would sell me the nuts for $.40 a piece but then they wanted to sell me the whole rocker arm with it (that would make them $3.90) autozone said they would be $9.95 for 12 but it turned out later that they were 9.95 for 4 so I didn't do that, so I never got them I checked the tolerences and they are .012" intake and .014" exhaust I didnt have to adjust any, but it is still very clicky with the solid lifters, how can I tell if it's too loud?
 

·
Registered
Joined
·
2,733 Posts
Wow! All I can think of is Jan and Dean singing "where were you when I needed you, where were you when I wanted you..."
Yeah. How to lock those stupid adjusting nuts. Pulled hair all last week over that thinking there must be some simple way to do that, gotta be some dumb Honda nut that fits or a 12 point aircraft fastener with the right thread and small enough head to get the bottom 15mm wrench out from under...
Samdog's poly lock/girdle setup is ultimate, but lacking time I went to my buddy machinist and borrowed a nice new sharp (made in Bosnia) 10x1.0 tap. Carefully drilled out eight 5/16 nuts with an 11/32 bit. Carefully threaded them with said tap. Put them on the stud above the stock rocker adjusting nut and locked them on. I noticed the locking part decreased valve lash, so some trial and effort was required to get the lash right. Be patient.
It ran three sets of six lap practice sessions at 6000-6500 rpm. Checked lash tonight and it was still perfect.
Would have been too easy to just go to Napa and buy some nut that worked.
But, that's racing! Keep the pointy end forward. (not like coming out of turn four of lap four in practice session two last night...) :eek:
 

·
Registered
Joined
·
2,733 Posts
I forgot to comment on Jordan and Paul's exchange about adjusting lash with solid lifters. I know the book and experts say do it with engine running...
I call bull. Maybe it's because I work on diesel trucks every day. And to our 302 in the race car before EVERY main event.
Set them with the engine warm but not running. Just be sure the lifter is on the base circle, not even close to starting to ramp up. Figure it out, you're all very intelligent!! Take your time and double check at least twice.
 

·
Old Opeler
Joined
·
5,564 Posts
NutZ!

Has anyone actually tried a GM/Chevrolet Dealer's Part store for the 60 degree V6 rocker adjusting nuts? The GM part number was/is #477212
:confused:
 
1 - 13 of 13 Posts
Top