[GUITAR1989]

Hey guys this question is for those of you with vortec heads. From what ive read some roller rockers wont fit on the vortec heads without modification.
What exactly is it that needs to be modified?
What roller rockers do you have on youre vortecs?
Did you have to cut into anything to get them to fit?
Thanks for your time guys

[MouseFink]

If you have a Vortec V8 w/center bolt valve covers, you need self aligning, narrow body rocker arms. I used Scorpion full roller rocker arms because the self-aligning rails are on the roller tip rather on the aluminum rocker arm. The rocker arm self aligning roller tip rails will not interfere with the valve keepers. However, for an extra margin of safety, I used Ferrea S.S. valves with a .256" tip for an additionl .006" clearance. I also used Comp Cams steel 10 deg. locks and retainers and got rid of the stock exhaust valve rotators. The .256" valve tips may not be necessary but I needed new valves anyway so I chose those.

Scorpion SCP-1035BL
Chevrolet 4.7L Vortec V8
1.5 ratio
3/8" rocker stud
self aligning roller tip (w/o pushrod guide plates)
narrow body (for center bolt valve covers)
.530" slot (for 3/8"-24 poly-locks)

The only modification I made was to enlarge the pushrod guide holes in the head to 7/16" for extra pushrod clearance. You should not use guide plates or pushrod guide holes with self-aligning rockers. If you want to use 1.65:1 rockers, you will need to use a Louis tool (Comp Cams) as a guide to elongate the pushrod holes.

[GUITAR1989]

So for self aligned i dont need guide plates..what about the hardened push rods? Also do i have open up the push rod holes to use self aligned rockers?
is there any preformance advantage in running non self aligned rockers? Like do they operate smoother or something? Why do people use them if Self aligned rockers are out there?

[lmsport]

Conventional guide plates and hardened pushrods is a more stable setup at high speed, ie greater than 6500RPM. Selfaligning rockers are fine for everyday use. The centerbolt cover makes the use of a stud girdle impractical, and the narrow body arm is not as strong as the conventional arm, but again, not a problem most street engines.

[MouseFink]

You can use self-aligning rockers without guide plates or use non-self aligning rockers with guide plates, but not self-aligning rockers with guideplates. You need to enlarge the pushrod holes in the heads if they are round, but only if you are using guide plates or self aligning rockers. In other words, you cannot have but one method of pushrod alignment because two or three alignments methods will not line up and will cause the pushrods to bind or rub. If your heads have factory self-aligning stamped steel rocker arms, you should use self-aligning roller rocker arms.

You do not need hardened pushrods with self aligning rockers but if you are going to install a high lift camshaft you will probably need longer pushrods, so you might as well buy hardened pushrods. Comp Cams as a good selection of High-Tech chromemoly hardened pushrods in various lengths in .050" increments.

[cobalt327]

Originally Posted by mf

The only modification I made was to enlarge the pushrod guide holes in the head to 7/16" for extra pushrod clearance. You should not use guide plates or pushrod guide holes with self-aligning rockers. If you want to use 1.65:1 rockers, you will need to use a Louis tool (Comp Cams) as a guide to elongate the pushrod holes.

Are you referring to "real" Vortec heads ('96-up)? Last I recall, you had a 4.3L V6 w/heads from a '92 or some such. The pre-'96 4.3L V6 engines might have been named "Vortec", but the heads are not similar to the L31 V8 heads until '96.

Originally Posted by GUITAR1989

So for self aligned i dont need guide plates..what about the hardened push rods? Also do i have open up the push rod holes to use self aligned rockers?
is there any preformance advantage in running non self aligned rockers? Like do they operate smoother or something? Why do people use them if Self aligned rockers are out there?

To begin with, L31 Vortec heads have 7/16" ROUND holes already in the heads- not slots- that the pushrods pass through. The earlier non self aligning rocker arm equipped heads have a 7/16" x 11/32" ovoid hole in them.

If using 1.6-up ratio rockers, there's a chance the Vortec's 7/16" hole will not be long enough. A Lewis tool is not the tool for the job, it only lengthens the slot, it does not widen it. And if using the earlier heads w/the ovoid slot, the hole through the head needs to be widened as well as lengthened if using increased ratio SA rockers- the Lewis
Lewis Tool.

So the best bet is to use a drill bit larger than 7/16" to open the holes up. Most often a 1/2” bit is used, I would use only as much size as was needed, but 1/2” will work. Drill at the same angle as the pushrods.

Enlarging Pushrod Hole w/1/2” Drill Bit. Note the undrilled stock 7/16" round holes closest to the camera.

As far as any advantage in performance, there isn't any that I'm aware of. SA rockers are generally more expensive and there's less selection for them. But they can be used w/straight shank screw-in studs, w/o guide plates- so in the right application that could save some money.