z28redline

Just swapping in an LT4 hot cam into my LT4 after wiping a lobe off the factory one and it looks like I'm going to need to replace one roller rocker that got damaged. Can you still buy these? GM says there discontiuned. I found the P/N 12367346 for a single unit but it says on the gmpd website that the "trunnions have been machined for early model 3/8" rocker studs" I assume this means that it won't fit with my factory LT4 studs. Can anyone confirm this?
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z28redline

STL94LT1

That one will work if you change the rocker stud, which is no big deal.

CDN/AZ LT4

Look forward to hearing about your initial impressions after you've completed your cam swap....pros & cons. Thanks, Peter

LT4BUD

This might help, from Grand Sport Registry Site.

"Both the LT1 and the LT4 Heads accomodate 7/16" studs but the LT4 has larger 7/16 rocker studs. There are some reports of early LT4's with 10mm top threads. The LT1 studs are 3/8" on top and 7/16" bottom. GM part numbers are #3921912 for 7/16" LT4 and #1255216 for 3/8" LT1."

STL94LT1

Hmmm, I thought all LT4's had 10mm studs.

racebum

what kind of mileage are on these? it's really not a bad idea to replace aluminum roller rockers around the 50k mile mark.

with the newer comp pro magnums out you get a lighter/stronger arm

z28redline

LT4BUD - The LT4 rocker arm studs are specific to the motor. The factory roller rockers don't have a set screw that threads through the rocker arm nut so there's no adjustment and you just tighten them all the way down on the stud.

STL94LT1 - I was trying to avoid replacing the stud if possible.

Racebum - The Rockers on this motor already got replaced on the recall once so I'm not sure of there exact age.

STL94LT1

Maybe put a WTB in the for sale section, and you might find a set that someone has pulled off their LT4. Most who modify their LT4 engines don't run the stock rockers.

BlackHarleyMan

They are 10mm

And if you need one, shoot me an email, I have a few of these things laying around from two different motors.

R/Noland

Gale Banks 80'

The Factory Rockers were made by Crane. I don't know if they are just a standard Crane Part or not. Crane is no longer around. There was a Factory Recall and all the Rockers were suposed to be replaced on LT4's so at one time there were Thousands of extras laying around.

mtwoolford

a couple years ago, with my 96 LT4, had the same problem; did the same cam swap; had one bad rocker; was able to get a single replacement through the dealer; it was a 10 mm stocker, but it was pricey; if I had it to do all over, rather than sourcing the cam and other parts seperately, I'd seriously consider one of the Hot Cam kits which include all new rockers and springs. In the end, it was well worth the effort.

93 ragtop

This may not be important, heck, it may not be correct, but dosent the factory arm adjust by a preload, be it in in. pounds or ft. pounds, where as the aftermarket, and the arms that come in the hotcam kit, adjust by removing all slack and then tightening an additional amount ie 1/4 to 1/2 turn.
If the above is true, I would not want to mix the two types in the same motor.

lt4obsesses

Same things happened to me. Had a lifter wipe out a cam lobe, and now I have a HotCam.

My rockers survived so I didn't have to replace them, but at 126K I'm thinking about it now. Anyway, the lower part of the stud for these is the 7/16 and the top is 10mm. Installation is a torque of 18ft/lb no preload adjustment. I believe ARP makes a stud with a 7/16 bottom and 3/8 top to accomidate aftermarket rockers for such an application.

A couple of things I learned the hard way on my journey in this.

1) When replacing the cam, go ahead and take a look at the rod and main bearings, check for heat and scoring. All those little metal shavings went somewhere.

2) If you go with a Hotcam, or other cam, have the car tuned ASAP. It will run pretty well w/o it, but it will burn rich at idle and may eventually burn out a cat.

3) While your there, check your oil pump, especially your oil pump drive gear, and for goodness sakes, if you do nothing else, replace that plastic drive gear mount in the intake with a steel one.

I tend to agree with the logic that if you are going to replace one rocker, replace them all. The Hotcam Kit really sounds like a good idea, I wish I had thought of that then. Also replace your lifters, the GMPP LS7 lifters seem to be pretty good.

z28redline

It seems that replacing the set of rockers and studs would probably be the best way to go. What do people recommend for roller rockers that fit under the factory LT4 valve covers? I'd like to stay away from aluminum if possible.

pr0zac

they were a 7/16ths stud with a 10mm nut. i have an lt4 thats how i know. the ones in the hot cam kit were 3/8s to accommodate the lt1 and sbc heads

racebum

http://cgi.ebay.com/ebaymotors/COMP-...#ht_3097wt_833

these, review the benefits vs aluminum and you'll probably see fairly quick why i linked them

96GS#007

Let's put the debate to rest. The key difference between the stock LT4 rocker arm stud and a conventional stud is that the LT4 stud is shouldered. As mentioned above, the lash is not adjustable.



A conventional LT1 stud is on the top. The base is 7/16" and will screw into any LT1 or LT4 cylinder head. The top portion is 3/8" and allows the use of self-aligning aftermarket rocker arms (ie 1.6 ratio arms from CompCams, etc) or stock LT1 rocker arms.

The stock LT4 stud is on the bottom on the pic. Note the shoulder that the rocker arm rests on. When setting up stock LT4 rockers, you still tighten them in the conventional sequence.

jlo

Hello, don't mean to hijack but I also have a set of LT4 rockers..and I need all the 10mm rocker studs to put in my vette along with the rocker locks..if any of you got spares let me know I have $$ in hand..