Self Aligning Rocker Arms (SBC)

[RickSE]

Any one know what the deal is with the self aligning rocker arms on post-1987 small block Chevy engines? What's the difference between pre & post 1987 rockers? Can the non self align rockers be used on late model engines?

Looks like on the non self align rockers Comp Cams states you must use guidplates. So maybe the self aligning rockers eliminate the need for guide plates?

I want to try 1.6 ratio rockers on my 1996 350 and need to make sure I buy the right rockers. The post-87 1.6 Comp Cams roller tip rockers sure are expensive, $192.

[jaroot]

I JUST installed a set of 1.6 ratio magnum roller tips on my 97 350 2V. the self aligning have skirts on either side of the roller to keep them centered over the valve tip. If you are using a performance camshaft you need to check pushrod clearance through the head, the slot through the head needs to be elongated with higher lift cams, with my production camshaft i didn't have any problem, the stock valve lift on my 350 2V was right around .395 intake and .410 or so exhaust (wrote it down after i indicated it, don't remember exactly). Adding th 1.6 ratio rockers nets you about 0.021 in more lift over stock 1.52 ratio rockers. I didn't see much performance increase after installing them, mostly i believe due to the restriction of air into the motor. Waiting on my throttle cable bracket for my edelbrock aluminum intake and 600 holley... we'll see how it goes... i think with all of this done stepping up to an MSD ignition would probably help out... i don't care for the thunderbolt V and their rev limiter setup and self controlling timing and all of that stuff... anyone know exactly what the thunderbolt V controls as far as initial timing and the curve? i get 30 degrees total advance i'd like to step it up to about 32 to 34 but from my understanding if i bump the initial timing to 14 to get this the computer will just retard it back...

Thanks

Jim

[BigGrizzly]

Rick use the guide plates been down that road before. at high rpms if a lifter hangs up it give problems. best part of roller rockers is the keep valve guide wear down and keep valve stems flat. I never got any HP increase just because of thr roller, that is just a sales ginnic. many hours on the dyno proved it

Randy

[Jamesbon]

Yeah, my GM Fast Burn heads required the self aligning rocker arms, however I opted to use non self aligning aluminum roller rockers which required the heads to be machined for guide plates. Just a metter of choice I guess.

[RickSE]

Thanks for the info guys, still not sure what I'll do. I need to check and see if the studs are pressed or screwed in. Pretty sure GM is still using pressed-in studs.

Jaroot,
I'm a few steps ahead of you. My 350 was a stock 2-barrel motor. I've since changed to an Edelbrock Performer Manifold, Holley 4150 650 CFM Carb, Crane 272/284 454"/480" Cam and Crane Valve Springs. The motor runs great, nice idle and lots of low and mid rang power. I ended up picking up about 5-6 MPH from the changes. I'd like to pick up a few more H.P. (maybe 10) and am hoping I can get there with the 1.6 rockers. I'm a little concerned though about the exhaust lift since switching to the 1.6 ratio will push the lift to .505". I'll need to check the valve clearance and the spring capacities.

I boat above 3600 ft. elevation and I've been trying to get to 60-MPH with this motor. I'm pretty close now at about 57-MPH but need something to push me over the edge.

I also have the Thunderbolt V ignition and thought the advance was fixed, meaning that if you bumped up the initial timing the total advance timing also went up. I may be wrong though, and don't remember what it did when I changed to 12 deg. initial timing.

[RickSE]

There's a $118 difference between "Full Roller" Rockers from Crane vs "Roller Tip" Rockers from Comp Cams. Does anyone think it's woth the extra $118 for the "Full Rollers"?

Full Roller Crane Rockers for post-1987 SBC $310.
Roller Tip Comp Cams Rockers for post-1987 SBC $192.

[Forrest]

If that's the choice, get the Crane Gold rockers, but IMO, in that same price range (Summit Racing Equipment (http://http:/www.summitracing.com)) the Crower Stainless Steel, or for a little less, the Comp Cams 4340 chromemoly steel roller rockers are both better than the Crane; however, all of these roller rockers, including the Crane Gold, are most likely an overkill for your application. You would probabaly do fine with a set of Crane Energizer or Harland Sharp full roller rockers in the $172.00 to $200.00 range.

Also, if you need to put in screw-in studs for guide plates, which you will if you don't already have them, consider using 7/16" ARP studs instead of 3/8", since they all cost about the same . . . and don't forget that you will need hardened push rods to go with the guide plates as well, and while you are at it, you'll probably want to . . . well, you get the idea.

------------------
Forrest

[This message has been edited by Forrest (edited 06-08-2001).]

[jaroot]

if i'm not mistaken... when you go to full rollers (fulcrum and tip), you'll need to go to higher valve covers. The low ones won't clear the adjusting nuts. With high lift cams you'll also need to check valve cover clearance with 1.6 ratio rockers on the low valve covers. Forgot to mention that earlier... if i decide to go the camshaft route in the future i'll probably just replace the whole motor while it is out... from the look of it... it can't be fun takin a sbc out of a 16 classic...

[BigGrizzly]

The stainless don't need taller valvr covers, ny bb doesn't have tal valve covers and its got rhe Crane ones. My Corsican has the stainless full roller rockers My Mustang -same engine type and built the same had the roller typ and both have the same power.

Randy

[RickSE]

Crane claims thier self-align Gold Series rockers are narrow enough to fit inside late model center bolt valve covers. I do need to find out if height will be a problem though. They also claim to have the only full roller self-align rockers on the market. Still not sure what I'll but thanks for the feed back guys.

[jaroot]

RICKS,

what drive are you running and what kind of prop? Stock i was turning 45 to 4600 at around 54 to 55 in my 16 (1.5 ratio alpha). With the motor being rev limited at 4650 it'll be hard to see what kind of gains i get in rpm. Just wondering if i'm going to have to really step up to a 21, HIGHLY doubt i'll pick up more than a few hundred R's Right now i am turning a 19P Vengance that isn't in the greatest shape... think the previous owner liked sandbars and gravel a little too much. need a spare prop anyway... well it's back together.. it runs... and sounds pretty healthy... playtime is tonight.. then the fun of tuning the holley begins. i reckon i'll be doing plug checks just about as often as those nascar guys runnin 5 miles away... least i can make some noise with em. IT'S FINALLY SUNNY AND WARM TOO!

[RickSE]

Jaroot,
I have an Alpha-1 GenII. I've been running the same prop as you, a 19P Quicksilver. I'm now at the point where I feel the prop is to small since I can easily push it over 5000 RPM's. I'd much rather have WOT yield around 4800 RPM's. Last summer I tried two props, a 21P & 19P Revolution-4. Although they're nice props they have too much bite and dropped my RPM's more than I wanted. This summer I'm trying a 21P Mirage Plus. Already tried it once at 4200 ft. with descent results and am hoping I'll have better results at my home lake @ 3700 ft. It does look like I could use a little more H.P. though to push the Mirage+ so that's why I'm considering changing the rockers.

The speed and RPM numbers of your 16 are really close to my old numbers with the 2-barrel set-up. I used to run about 53-54 MPH at similar RPM's. This is for an 18-Classic again at 3700 ft, 1.47(.49?) ratio drive. Are you sure about your rev-limit? I was worried about hitting mine after the induction changes but was told all Merc. rev limiters are set around 5200 RPM's. I certainly haven't hit mine running up to 5100 RPM's. I have all my numbers somewhere and think I've picked up 400-500 RPM's with all the changes so far. I'll try and dig out some of the old numbers.

[jaroot]

Hope you are right about the rev limiter... sure would make life easier. I have the mercruiser service bulletin from oh around 1996 that says the motor is rev limited 50 rpm above the WOT max RPM and once you hit the limiter you have to drop 300 rpm for the module to discontinue rev limiting the motor... my 350 2V's wot is 42 to 4600... figured out last night that either my information is incorrect or my tach is off a couple hundred RPM... seems as though the thunderbolt wants to maintain 475 to 500 rpm at idle on my tach when i was trying to set it at 650 or so... set the timing and idle in base mode... take it out and it'd retard the timing and put me at 500... although my motor info says 650 rpm in gear... oh well, reckon i could get out my IR digital tach but it is hard enough to get my hand down in there through the little access door behind my seat to mark the pulley let alone get a piece of reflective tape on it.. once i figured it all out i got the initial bumped up to 14 so i get about 34 advance instead of 30 now... see if it helps with the extra fuel otherwise i'll back it off a tad. lets hope the rev limiter is above 5K eh... might be time for that MSD... anyone that has the marine setup (distributor, 6M-2 and soft touch) want to let me in on where to get a decent price...

Thanks

Jim