Rocker Arm upgrade guidance needed
 

I want to move up from a 1.5 ratio to 1.6 ratio rocker arm on my 383 and I want to make sure I make the right choice in rocker arms the first go around. These are going on factory vortec heads on my roller cam GMPP HT383 specs here

Here's a write up Hot Rod Mag did on this same engine several years ago. Their first step was to upgrade the rockers and they chose Comp Cams Pro Magnum 1.6:1 rollers.

http://www.hotrod.com/how-to/engine/...block-tune-up/
http://image.hotrod.com/f/9547764+w6...mage_large.jpg

Looks like I need self aligning rockers, found these from the current offerings from Comp Cams

http://www.compperformancegroupstore...UltraProMagnum

http://www.compperformancegroupstore...1/1601_600.jpg

I've also found these Scorpion Racing Products rocker arms to fit my application.

http://www.scorpioncheckout.com/category_s/85.htm

And lastly these GM rockers...

http://paceperformance.com/i-6255517...set-of-16.html

http://paceperformance.com/images/M20045444.gif

I need to figure out if my heads have 3/8s or 7/16s studs, is anyone for sure on that enough to save me from pulling the valve covers to look?

Also, does anyone have any experience with any of the above, either good or bad? I do have aftermarket tall valve covers but they are still the center bolt design can be a bit of an issue clearance wise with some of the above, mainly the Comp Cam rockers. From what I read the Scorpions are a bit narrower which fit real nice with no trimming necessary.

It's not a high revving engine, probably will never see above 6,000 RPM, so a street rocker should be fine...but I'd like to get any advantage I can while making the change and would prefer to do this right and once vs trying to cheap out. If anyone has any other recommendations I'm open to them as well.

Thanks for any insight you may have...

Well, I'm using the GM 1.6 self aligning rollers on my ZZ430.

They are 3/8 studs.

They clear the center bolt covers no problem.

I have been using them for about 14 years and still going strong.

Thanks Don. Those aren't Vortec heads on that engine though, are they? not sure if that makes a difference or not.

Good to know the GM rockers are doing well though.

Lance, I've used the vortech head on a couple of engines, and they are 3/8" studs. As far as rocker upgrades, it's a great idea to go to the 1.6's, but I'm not gonna dare recommend one over the other, because I don't know what fits the center mount valve covers. I like the ultra pro mags, simply for the weight out over the spring. I welded tabs on my heads to utilize perimeter bolt valve covers, because I went with Crower shaft mount rockers. These were race engines, for a steel headed circle track class. Again, I'm no help...

Lance, they are Fastburn heads which are basically aluminum Vortecs.

Thanks guys... What about Chrome Molly Steel vs aluminum rockers on basically a street engine that gets run hard on occasion at the track?

Should this be a concern for me?

FWIW,
I have 1.6 aluminum Proform rockers on my 406 w/vortec heads. It's a solid roller and I have beat it up pretty hard, no failures in the last 9+ years it's been running.
I believe mine were 3/8. I have taller valve covers on them. I do believe they hit the valve cover at the corners (front & rear) so I had to grind them down a little where their square edge is. I suppose this can change based on the exact valve cover used.. Mine were some billet aluminum ones.

-Dale

Lance, I recommend Harland Sharp roller rockers. I have been running the same set for 30 years and have not had a single valve train related problem.

http://www.summitracing.com/parts/cs...make/chevrolet

But please, before you switch ratios check your valve to piston clearance and also your valve springs for coil bind! Going from 1.5 to 1.6 will make the valves open further so you need to make sure the valves are not going to hit and springs are not going to bind. Don't rely on what some magazine says will work, they are not going to fix your engine if it goes wrong. I would hate to see you install 1.6 rockers only to bend some valves or break some springs and be sidelined for the season from engine damage. It can get pretty expensive to repair that damage.

Lance ---



I think I have a couple sets of 1.6's that will forever be un-used..... and since they're not the self guided --- they would require "guide plates" which I think I also have a couple sets of -- If you'd like -- you'd have to wait until I'm home from my trip to the USCA event and I'll check to see what's laying around and they'd be FREE to you if you wanted to use them.

What you'd then need to find out is if your heads will take guide plates.

If GW's don't work I'd lean toward the Comp Cam Pro Mag's, not the lightest but I'm guessing they may be some of the stronger more durable choices.

Yes........I have stayed at a Holiday Inn Express. :D