One of the most common valvetrain upgrades for pushrod-style engines is roller rocker arms
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00:00 This time on Engine Masters, we are going to test a whole bunch of rocker arms to find out if a roller rocker is worth your time and money.
00:09 [Music]
00:30 Alright, this is Engine Masters presented by AMSOIL and the episode where we ask, "Is a roller rocker arm really worth it?"
00:39 Now the thing is, this is also the episode that you overhead cam guys are going to hate because your engines don't have these.
00:45 So maybe I should explain to you what they do.
00:47 The rocker arm is basically a little implement of leverage that is the thing that opens and closes the valve.
00:54 You start down here with the camshaft rotating and then that translates lift through the tappet, through the pushrod, right here into the rocker arm,
01:01 which multiplies that lift, usually by a ratio of about 1.6 to 1.7 to 1, and opens and closes the valve.
01:09 The thing is, there's a lot of aspects of the rocker arm that can affect performance and that's what we're going to find out here today.
01:16 Now the engine I chose to work with runs to 7,000 RPM.
01:20 And the reason for that is, if we're going to see anything as far as improvements from frictional loss in any of these rocker arms,
01:27 we're going to see it at higher RPM.
01:29 If we don't see any improvement at higher RPM, you can pretty fairly conclude that it's not going to have any effect on your engine
01:36 that only runs, say, 5,800 or 6,000 or something like that.
01:39 But, the engine I chose is actually pretty wicked.
01:43 It's a 372 cubic inch small block Chevy.
01:46 It's got stuff like a single plane intake manifold, big AFR 195 heads.
01:50 It does turn 7,000 RPM.
01:53 So we're going to find out what that kind of RPM does to all sorts of different rocker arms,
01:58 starting off with that stock type stamped steel unit.
02:02 We're going to bolt these onto the engine, roll it into the dyno, fill it up with some AMSOIL, and fire it up.
02:07 So much of the test that we're doing today has to do with friction,
02:11 because that's what you're eliminating or reducing when you're putting in that roller bearing inside a roller rocker arm.
02:17 The thing is, I don't really know if we would see more of a difference here if we were running conventional oil,
02:24 but I don't want to do that anyway because we always run this thing on synthetic.
02:27 Today we're going to be putting in the AMSOIL Z-Rod 2050,
02:32 and I'm really looking forward to it because with my clear valve cover,
02:36 I can watch the oil slurp down into the engine.
02:40 [The Review]
02:43 Okay, we're set for our baseline, the very first run with the scrub rockers.
02:47 I think it's a little unusual to use a stamped steel rocker with a cam this big.
02:51 I never have.
02:52 Never seen it, right?
02:53 This is my first time.
02:54 One thing cool about these rockers though is when I was assembling it, it was a 7/16 stud,
02:58 and I thought, "God, we may have a chance on this thing staying on."
03:01 [laughter]
03:02 I put some polylocks on it, got rid of the nut, jammed nuts, and put some polylocks on it.
03:07 But it's cool that it has a 7/16 stud.
03:09 He's talking about the stud that the rocker arm goes on in a small block Chevy
03:13 can either be 3/8 or 7/16 diameter,
03:16 and obviously you'd rather have the 7/16 when you're dealing with this stuff
03:19 because 3/8 flexes to the point of snapping off.
03:22 7,000 RPM in this much cam.
03:24 Yeah.
03:25 But there are classes that call for a stamped steel rocker.
03:28 Yeah, circle track stuff.
03:29 I think that's why these Howard's stamped steel rockers exist.
03:33 Probably why they exist.
03:34 Even though these are aftermarket, I would say that what we're about to do test-wise here
03:39 is the same as if a guy had just got the stock rocker arms off his engine, right?
03:43 Yeah, absolutely.
03:44 I mean, there's nothing unique about it other than it's just beefed up a little bit, which is cool.
03:47 How about the size of the ball?
03:49 The OD of the ball is the same size regardless of the ID of the hole for the stud, right?
03:53 You know, I haven't measured the ball diameter.
03:55 Right.
03:56 The center hole is obviously bigger, and the stud is going to have to have--
04:00 or the rocker is going to have to have a little wider slot.
04:02 So it may very well be that it's got kind of a cup of a big block and the ball of a big block
04:07 with the ratio and length of a small block.
04:09 Like I say, it's kind of a cool rocker.
04:11 And they sell this in a 1.6 too, even though we've got 1.5s on it now.
04:14 And the long slot is also a consideration if you've got a lot of lift,
04:17 because you've got to make sure it doesn't bind up, or that could be catastrophic.
04:22 So those are going to win.
04:23 We haven't been there yet, but we're about to see 7,000, so--
04:26 Yep.
04:27 You think this thing is ready to go?
04:29 Yeah, it's perfect temp.
04:30 OK, we already have a tune-up on this thing, so this is just going to be one or two pulls for our baseline.
04:36 Then we'll get to throwing some other junk at it.
04:38 [MUSIC PLAYING]
04:41 It's a nice little motor.
05:04 Yeah.
05:05 This is-- I already know what it does with roller rockers, because we've had them on it.
05:08 Oh, OK.
05:09 He always cheats.
05:10 I know.
05:11 I won't reveal that, but this is pretty good.
05:13 Yeah, it is good.
05:14 It actually is pretty good.
05:15 Yep.
05:16 And then we've got a 500 horsepower 372 with stamped steel rockers.
05:20 So we just made 470.3 pound feet of torque at a big 5,000 RPM.
05:25 And way up here at 6,600, it made 508.8 horsepower.
05:29 And it's a beautiful thing.
05:30 That's all we need to know.
05:31 We're going to go in there and throw on the roller tip.
05:34 Well, that was pretty cool.
05:35 But I know what you're thinking.
05:37 Where did he get those transparent valve covers?
05:39 Yeah, those are pretty cool.
05:40 They're made by a company that's called Clearview Concepts.
05:43 And I bought them through Classic Industries.
05:45 And I know you need a set.
05:47 Actually, you're going to find ours leaking everywhere, because we had to double stack the gaskets on them.
05:51 So if you buy them, I recommend buying thicker gaskets than what the company actually recommends.
05:55 Next, we're going to talk about the six ways that rocker arms can affect power.
06:00 Number one by far is the rocker ratio.
06:03 In other words, how much they amplify the lift at the cam to the lift at the valve.
06:08 For example, the stock Chevy is 1.5 to 1 ratio.
06:12 Aftermarket frequently has a 1.6 to 1 ratio, which actually small block Fords have that stock.
06:17 So think of it this way.
06:18 If you have 500 thousandths lift at the camshaft and multiply that by 1.5 to 1, that means you have 750 thousandths lift at the valve.
06:28 If you multiply it by 1.6 to 1, you have 800 thousandths lift at the valve.
06:32 That's a big difference and it contributes to airflow.
06:34 Number two, friction.
06:36 Think of this.
06:37 At 7000 RPM in a four-stroke engine, this rocker arm has to open and close the valve 58 times per second.
06:45 And with the camshaft lift we're running today, that means the tip of the rocker arm is moving at almost 5 feet per second.
06:54 You would think that would add up to a lot of friction, especially on the stock rocker arm with this kind of ball.
06:59 And so you'll see a lot of advertising that says that the roller trunnion in a roller rocker will eliminate that friction and therefore make more power.
07:07 Number three, flexibility of the rocker arm itself.
07:11 If you have a flimsy rocker arm and a lot of valve spring pressure, it can actually bend the rocker dynamically while the engine is running,
07:18 which reduces lift at the valve, which ends up costing you power.
07:22 The same is true of number four, which is stability of the way the rocker arm is mounted.
07:28 On a small block Chevy, typically it's on a stud like this.
07:32 This is a 7/16 inch stud.
07:35 This is a 3/8.
07:37 3/8 is flimsier.
07:38 7/16 is stronger.
07:40 There's also ways to convert these to a shaft rocker and other ways to just stabilize the rocker itself,
07:45 because if these start to bend and lose control, you lose power.
07:49 Number five is weight or inertia.
07:52 If the pivoting part of the rocker arm is really heavy, that is part of what the valve spring needs to control.
07:59 If it's heavy, it can end up leading to stability problems, in other words, floating the valves, and that can cost power.
08:05 Of course, number six is straight up reliability.
08:09 That's a big deal with rocker arms.
08:11 If one fails on you, obviously you've got a dead cylinder.
08:14 Here's the first rocker arm that we just tested.
08:17 We were pretty impressed with it because while it looks like a bone stock Chevy stamp steel rocker arm,
08:22 it has some significant upgrades from Howard's cams.
08:26 First of all, it uses the larger than stock 7/16 inch stud.
08:31 That means it's got more valve train stability than the flimsier 3/8 stud.
08:36 We think that helped it a lot in this particular application.
08:40 In order to be able to survive with a camshaft like we're running today with a lot of lift,
08:44 it's also been modified with a longer slot here at the bottom
08:48 so that the stud doesn't end up limiting the travel of the rocker arm.
08:54 These are $110 and I would say a pretty good deal and super, super simple.
08:58 Those are from Howard's cams.
09:00 Now let's talk about the next three that we're going to test, which all fall into the category of roller rockers.
09:06 This particular one would be the poor man's roller rocker because it only has a roller tip.
09:12 It does not have a roller trunnion.
09:14 It uses the ball in it just like a stock rocker arm.
09:19 Also, I shopped around a lot and I could not find a roller tip only rocker arm
09:24 that used that big 7/16 inch stud, so this one takes the tiny 3/8.
09:29 I got a trick super strong 3/8 stud from ARP to do my best to try and stabilize the valve train.
09:37 We'll see what happens.
09:39 It's really important for me to point out that this part right here looks a lot like something that you can buy from Comp Cams.
09:47 However, it's not.
09:49 This thing is advertised at 1.5 to 1 ratio, whereas Comps are 1.52,
09:53 and that's why I thought this would be a more realistic comparison with the other stuff we've got going.
09:58 However, this thing is cheap. I might have made a mistake there.
10:02 Next up is the full roller rocker arm, which means it has a roller on the tip
10:06 and a roller here at the pivot or trunnion.
10:09 Now, when shopping for this thing, I really wanted something that was a good value.
10:13 This is $257.
10:15 However, I wanted to make sure that I did not get a cheap import knockoff
10:19 because from experience, I can tell you those break, and when they do,
10:23 the little needle bearings go all through your engine and turn it to trash.
10:27 This Scorpion is made in USA.
10:30 Other good quality made in USA rocker arms will come from companies like Comp Cams, Crane Cams, stuff like that,
10:36 and they are more expensive.
10:38 I've never used these Scorpions before, so we'll find out how the reliability is, at least here on the dyno.
10:43 Now, this one is 1.5 to 1 ratio.
10:46 The last rocker arm that we will test is also a Scorpion.
10:49 It's exactly the same, but it's a 1.6 ratio for more valve lift.
10:54 So, next up, we're going to burn through all three of those rocker arms on the engine
10:58 to find out which one is best and which is worst.
11:01 [music]
11:13 Okay, ready to go with the roller tip rockers.
11:17 What do you think it's going to do, forever?
11:19 Zero.
11:21 So, you're saying this is going to make a difference?
11:23 Well, I think the 3/8 stud negates anything the roller tip may add.
11:27 What do you think, David?
11:29 Zero.
11:30 Zero?
11:31 Zero.
11:32 It'll be great if it loses power.
11:34 That'll really be awesome.
11:35 That'll definitely tell us that it's the flimsy stud.
11:38 [engine revving]
11:59 Wow, they worked.
12:01 Yes.
12:02 I wanted to see one break and fly through the clear valve cover.
12:04 Somewhat adequately, but I think--
12:06 Let's look.
12:07 Wow.
12:08 Oh, boom.
12:09 Yeah.
12:10 So, the red line shows us that the stock stamped steel rocker arm
12:13 actually made more power from 5,000 RPM on up.
12:17 And our theory is that that's because that smaller stud is flopping around.
12:21 I would almost bet because, you know, down here it's not,
12:24 but with that more and more engine speed, it just gets worse.
12:26 And I think there's just a ton of deflection.
12:28 That's all stud.
12:29 Yeah.
12:30 Yeah, but the thing is, I think it's still a fair test on the roller tip
12:33 because you can't buy it for a 7/16 stud, at least that I found.
12:37 And so that's what you put up with.
12:39 And I think this tells you, though, that even if you have a 300 horsepower 350,
12:43 that rocker arm's not doing anything for you.
12:45 I agree.
12:46 The only point, though, is I noticed that like Comp Cam sells these
12:49 and in their advertisement, they don't say it makes power.
12:51 They say that it improves valve stem tip wear.
12:54 And that's certainly a possibility.
12:55 There's no rubbing.
12:56 But now, let's throw the roller rockers on and let's make power.
13:00 Yeah.
13:01 Ready?
13:02 [MUSIC]
13:23 Well, here's your final answer on the roller rocker.
13:25 Didn't make any difference whatsoever as far as improvements.
13:29 It was actually worse way up here in the top just by a few numbers.
13:32 But that's probably because the rocker arm is heavier
13:34 and we're creating a valve spring control problem up there,
13:37 which is only going to get worse when we go install the 1/6s right now.
13:40 And those will make power over here, but probably get way worse.
13:43 Are you sure?
13:45 I'm sure of nothing.
13:48 Okay.
13:49 I think the 1/6s are going to be better.
13:51 [MUSIC]
13:54 One of the things you need to make sure of when you're installing
13:56 any of these roller rockers is that you get the trunnion the right side up.
14:00 If you look in there, you can see that it's flat on one side,
14:03 which is where the polylock seats on it.
14:06 Whereas if you flip this thing over, it's not machined flat,
14:11 and this doesn't fit right.
14:13 We call them lightning lash brulee.
14:15 No one can go through 16 valves quicker.
14:18 A lot of times what you'll see guys do is they'll pre-adjust the valve
14:22 and then they'll try and use the set screw to jam it.
14:26 And what you frequently find is the rocker arm comes loose.
14:30 So what I do is I'll bring it down basically to zero.
14:34 I'll put a quarter turn preload in it, and then I tighten the jam screw
14:38 and then tighten them both together.
14:40 That absolutely ensures that that's locked.
14:43 It's a little more tedious with a solid lifter camshaft
14:45 because you've got to find that spot where you've got the right lash
14:48 and it's jammed, but it's time well spent
14:50 because otherwise you end up with a whole bunch of studs coming loose.
14:53 [Music]
15:21 Wow. If I wasn't a fan then, I am now.
15:24 Wow, significant. That was really good.
15:27 You know what it is? It's that Airflow Research head.
15:29 It likes the more lift because it's going to move more air.
15:32 In the end, the 1.6 roller rocker made 473 pound-feet of torque at 5,100
15:37 and 526 horsepower at 6,700.
15:42 And what's the overall gain compared with the 1.5 to 1?
15:47 Huge.
15:50 It made 20 horsepower by changing the ratio from 1.5 to 1.6.
15:55 What we're looking at here is our worst curve in black,
15:58 which is the roller tip only rocker arm,
16:01 and then the best with the 1.6 full roller Scorpion.
16:05 That's a huge difference.
16:08 Yeah, and the price difference is 150 bucks.
16:11 It's $110 at Summit for the roller tip, and it's $257 for the full roller.
16:17 So if you've got the cylinder head, a 1.6 is definitely an advantage.
16:21 Cylinder head and valve train, that's a lot of power for $100.
16:25 And reliability.
16:27 Wouldn't you say the active ingredient there is not so much the roller but the ratio?
16:31 Oh, absolutely. It's 100% the ratio.
16:34 You're perfectly clear on that.
16:35 Yeah, that's the biggest thing about it.
16:37 So if you've got the valve spring for it, the coil bind clearance for it,
16:42 the valve to piston clearance for it, the pushrod clearance for it--
16:45 The cylinder head for it.
16:46 The cylinder head for it, then the 1.6 is the way to go,
16:48 and we happen to have all of those things in order, and it made huge power.
16:51 So now we can go turn the air conditioner on?
16:53 Yes, please.
16:54 Yes, please.
16:55 Okay, we're going to talk about how to apply this to your life and your engine,
17:03 but first I want to verify that we did check the rocker ratio on all of these.
17:08 Sometimes an OE rocker can have less lift than intended
17:12 because the ratio is actually 1.4 to 1 instead of 1.5 to 1, but we did verify them all.
17:18 So let's go into the pros and cons one by one.
17:21 I think the pros on the stamped steel rocker was that it's cheap,
17:24 and it worked way better than expected.
17:26 It's really good.
17:27 But I think the key to that is that 7/16-inch stud.
17:31 I think on a standard small-block Chevy with a 3/8 stud, especially a push-in one,
17:35 this would be a fail.
17:36 Yeah, and also the polylock because the stock nut will go back out sometimes.
17:40 Yeah, you definitely want to run the polylock on this thing instead of the factory Stover nut.
17:45 And I would also say, you know, we kind of worked a miracle here
17:49 with this much camshaft on a stock steel rocker.
17:51 If a guy's got an engine over 6,000 RPM, that's probably not his guy.
17:55 How about pros and cons on the roller tip rocker arm?
18:00 I can't really think of anything I love about it.
18:02 What about you?
18:03 Let's think of the pros.
18:05 It opens the valves.
18:07 Okay, no thank you.
18:09 How about pros and cons on the full roller rocker?
18:13 I thought a pro was going to be that it was going to make 4 or 5 horsepower, and it didn't.
18:17 A con is it's a little more expensive, but this can take way, way more load than a stamped rocker,
18:22 especially with high spring loads, big, fast, high-lift cams.
18:26 So basically what that's buying you is reliability, right?
18:30 And then the winner, the 1.6-to-1 full roller rocker that gained us 20 horsepower.
18:37 That's an obvious pro to that one.
18:39 Doesn't always happen.
18:40 I know. I think it's because we have these AFR 195 heads.
18:43 They were really able to use the extra, whatever it was, 37,000th lift.
18:47 That was a big deal.
18:49 But there are significant cons to using this thing, too.
18:52 Yeah, depending on the engine combination, sometimes you can reach instability way faster
18:57 in the valve train or valve float when you start jacking the ratio up.
19:01 Because it's accelerating the valve much faster, but even more basic than that...
19:04 You have to make sure it fits!
19:06 Right! This thing has more lift, and so you've got to check everything that you would
19:10 if you were putting in a camshaft with more lift.
19:12 We're talking retainer-to-guide clearance, coil bind, valve-to-piston clearance, all of that stuff.
19:17 And it can run into problems like with pushrod clearance up against the head.
19:21 There's just a lot you have to go through to make sure you're totally dialed in
19:24 if you're using a high-ratio rocker.
19:26 But in this case, totally worth it.
19:28 Win all the way around 20 horsepower.
19:30 I know. And I learned a lot on this episode, like we always do,
19:33 on Engine Masters, presented by AMSOIL.
19:36 [Bloopers]
19:41 I would love to see one of these break off and shoot through the plastic valve cover.
19:45 That would be the best.
19:46 It's worth the $400 valve cover and that $8,000 small block.
19:50 That's not my small block.
19:53 [Engine Revving]
19:56 [BLANK_AUDIO]