JorgeG79

I recently installed a BTR truck norris cam, BTR valve springs and 7.400 pushrods. This was the first time I ever worked on an engine's internals and well I got the cam swapped and valve springs and seals replaced without any issues but when it came to torquing the rocker's arms I made a pretty big mistake. I torqued all the rocker arms to 22/lb at once without making sure the valve springs didn't have tension on them. When I turned the engine over by hand it shot a rocker arm and broken rocker arm bolt into the air. I spent a lot of time extracting that rocker arm bolt and was hoping that was the full extent of the damage.


When I went to turn the engine over to get cylinder one at tdc the engine would not turn over. After I put a cheater bar at the end of my ratchet and I was able to get the crank to turn. My timing chain seems to be turning normally but my valves are not moving at all when I rotate the engine. All my valve springs don't have any spring pressure on them and none of the springs look to compress or move when I turn the crank. I didn't originally intend to pull the cylinder heads but it is looking like I will have to in order to examine my lifters and valves because the two fixes I tried so far didn't work for me. One fix attempt was to pour a quart of oil into the valve springs while I turned the crank over and then I tried with the cam sprocket off and turning the cam by hand after I poured another qt of oil on the valves and neither of those two times I tried to lube the lifters and valves seemed to have fixed or changed anything. I was hoping someone on here would be able to offer an explanation or share their thoughts on why none of my valve springs seem to be moving or opinions on what else might be damaged on my engine.

JorgeG79

the pushrods are all the same length and are the one that came with the cam kit. The problem I have where the intake and exhaust valve springs are not moving is with the rocker arms off and the pushrods not installed. I am turning the engine over by hand and none of the valves or valve springs are moving but my timing chain and cam sprocket are rotating.

my problem came after I torqued all my rocker arms at once without making sure the valve spring wasn’t under pressure. Before that all my intake and exhaust valves moved when I turned the engine over.

gametech

iTrader: (1)

Let me get this straight. You say you are turning the engine over with the rocker arms OFF and want to know why the valve springs are not moving? Is this a joke?

gagliano7

Without the rockers nothing moves. That is how the valves open and close. You want the the rocker you are working to have the cam lob for that rocker to be on the base circle when you tighten them.

https://www.motortrend.com/how-to/ccrp-0702-camshaft/

Tommy42088

Put it back together and make sure you have zero lash when torquing to 22 pounds. The way I always do it is I spin over the crank and you will see each rocker as it goes up and then turning it just slightly more you will see it gets real loose, at that point torque that particular rocker to 22 pounds. Do this on each one until you have them all torque. Also the 7.4 pushrods should be fine if your working on a factory 5.3 which I'm assuming because you stated truck cam. That's what pushrods were in my truck before I did any milling and they were fine. I also have a truck cam in my truck.

MuhThugga

♫♫ The lifter bone is connected to the...pushrod bone.
The pushrod bone is connected to the...rocker bone.
The rocker bone is connected to the...valve bone.
That's how your valves will open. ♫♫

TurboBuick6

iTrader: (2)

There is a major issue here. You broke a rocker arm bolt turning the engine over and shot the rocker into the air?

You may need to upload a video of you turning the engine over. You should NOT need a breaker bar to turn this engine over fully assembled.

Did you replace the lifters? If so what type, link bar or tray?

RB04Av

I'm not sure whether this is a real person with a genuine problem, or just a troll. Anyway...

In this kind of motor, the valve train is not adjustable. You simply install the parts, tighten them down, and go. The only form of adjustment in it is the push rod length. This must be chosen so that the lifter is somewhat more or less centered within its range of internal travel. Stock lifters have something in the neighborhood of 1/8" (0.125") of travel, meaning that the ideal preload is somewhere around .050" - .080". Not particularly critical. Most aftermarket cams are slightly different from stock cams (after all, if they weren't, they'd be ... stock), and one of the differences is, sometimes they are a different diameter, and therefore require a different push rod length to achieve preload within the acceptable range.

That said, the difference usually is relatively minor, and with a cam that's not all that much different from stock, like that one, it's usually not much of an issue. I would put the odds of broken rocker bolts being due to incorrect push rod length at somewhere between .00000001% and .0000001%. Pretty tiny. Highly UNlikely.

More likely, the reason you broke parts was, the cam was not timed to the crank properly, therefore the valves hit the pistons. That's the first thing I'd check: the alignment of the timing sprockets.

The rocker bolt tightens down metal against metal. The rocker trunnion is a metal shaft; the rocker pedestal is a metal block; the bolt holds them together. The ACTUAL rocker torque isn't ACTUALLY supposed to be 22 ft-lbs; the ACTUAL spec, since it's metric, is 30 N-m. Notice the high precision here... if you go and look up the "standard" torque spec for that size of hardware, it's ... 30 N-m. Note that the number has ONE significant figure: this means that it JUST ISN'T that important. The ONLY reason there's a torque "spec" AT ALL, is because the factory uses automatic assembly equipment, and it has to be set to SOMETHING; so they use the "standard" spec for that size of hardware, and of course they publish it, so ... that's what we all do out here, too. 1 ft-lb is approximately 0.737562 N-m, therefore to convert between the metric and Imperial units, you multiply N-m by 0.737562. 30 N-m = 22.12686 ft-lbs. But we can call it 22 ft-lbs because that's the degree of precision we started out with: just like you can talk about something inherently imprecise, such as for example how far away you can hear a sound something makes, let's call it "about 1000 meters", there's no need to describe that as "about 3280.84 feet". Even calling it 3300 feet is already more precise than the thing you're actually measuring. Measure with micrometer, mark with chalk, cut with axe.

The torque on the rockers is not the least bit critical. Nor is whether the cam lobe is on its base circle. Nor is ANYTHING ELSE. It's METAL TO METAL; it needs to be "tight enough" (won't fall apart), but not "too tight" (strips threads and breaks parts). To put it into perspective, the valve spring pressure at full open, is usually something around 300 - 350 lbs; since the rockers in this type of engine have a 1.7 ratio, that means that the pressure on the bolt is about 2.7 ÷ 1.7 times that, or something about 500ish lbs; since the rocker bolt has a thread pitch of 1mm, or roughly 1/25 of an inch, that means that the threads of the bolt have leverage of about 25 × 12 expressed in measurements involving feet, which is roughly 300; that means that the 500ish lbs of force at the rocker bolt from the valve spring tension results in about 1.5 ft-lbs of torque on the rocker bolt. Whether you put sealant on the bolt threads or chased them to clean them out first makes MORE DIFFERENCE than the valve spring EVER will. It's INSIGNIFICANT. For that reason, ignore all the drivel about "rocker loose": while it's certainly "true", and "theoretically" accurate, it's just like talking about hearing that "about 1000 meter away" noise at 3280.83 feet but not 3280.85. Too much precision to fit the real world. Measure with micrometer, mark with chalk, cut with axe. Just tighten the damn things up already and move on.

Enough ranting about excessive pointless irrelevant attention to insignificant and immaterial details while ignoring things that really matter: aka being easily distracted by shiny things off to the side of the path instead of remaining focused on your journey ahead. Rocker torque isn't the problem here; push rod length is extremely UNLIKELY to be; focus on things THAT CAN ACTUALLY CAUSE WHAT HAPPENED, TO HAPPEN.

Remove ALL the rockers and clean up the mess. Get whatever new bolts etc. you need. Verify the push rods aren't bent by rolling them on a piece of glass, and if you hear clicking noises as you roll them, replace them. Then, on to the meat of the matter. Check the timing sprocket alignment. To do this, bring the #1 (front left) piston to top dead center (look into the spark plug hole to see it), then verify that the mark on the crank sprocket is pointing straight up; then rotate the cam so that when you put the sprocket on it, its mark is pointed directly downwards at the crank. This is the condition commonly referred to as "dot to dot", and is #6 firing . Understand that at this setting, #1 & #6 pistons are both at TDC; #6 is firing, while #1 is at the point in the cycle where the exh valve is just closing (end of exh stroke) and the int valve is just opening (start of int stroke). Exactly one crank rev later, the crank dot will be up again, the cam dot will be straight up instead of straight down, the #1 & #6 pistons will both be at TDC again, except this time #1 will be firing and #6 will be at that other point. Once you have that set properly, bolt the rockers back on, put it the rest of the way back together, and fire it up. Hopefully none of the valves are bent or anything else got damaged butt who knows; probably won't be obvious what if anything else you tore up by screwing it up until you get it running again.

JorgeG79

I did not replace the lifters or lifter trays. All I have done is extracted the broken bolt and bought new rocker arm and bolts with the trunion upgrade installed. I have yet to install them because I saw that none of my valve springs looked like they were compressed and didnt want to go about installing the rocker arms till I got to the bottom of what other damage I might have caused.

JorgeG79

I wish this were a joke but like I said in my original post this is the first time I work on a engine's internals. From what I am gathering from this post is that the valve springs do not move when you turn the engine over unless the rocker arms and pushrods are installed?

JorgeG79

Thank you! This is probably common sense for most of you but to me I was concerned that my pistons made love to all my lifters or valves since the springs weren't moving with the crank but I am feeling better about starting to put the engine back together.

JorgeG79

Thank you for taking the time to write this up! I will do everything you said like verify my timing is correct before I torque the new rocker arms on with the new bolts I bought. Hopefully, that broken bolt was the full extent of the damage but like you said I will probably not know until its put back together and fired up.

ddnspider

iTrader: (26)

This is the first time I've heard someone say that bolting the rockers down precisely doesnt matter, not even being on the base circle. I'd be curious if some of the engine builders like @Che70velle and @KCS think the same thing.

Old Buzzard

"I'm not sure whether this is a real person with a genuine problem, or just a troll. Anyway..."

^^^ This.

G Atsma

How ELSE would the valves open?? What do you think the cam does with the pushrods and rocker arms??
You have a LONG way to go on learning how an engine operates. Learning that should have taken place long before now...

RB04Av

It's just LOGIC. Nobody even has to "say". Just LOOK AT IT and observe: it's solid METAL TO METAL. Nothing bends, moves, crushes, compresses, or otherwise changes in any way, from the point they're "tight enough" until they reach such a tightness that it starts destroying parts, at which point they're "too tight".

As long as they're "tight enough" to be held down solidly and not come apart, but not "too tight" to the point that bolts break or threads strip, NOTHING ABOUT ANY OF IT CHANGES.

We don't need the logical fallacy of "appeal to authority" to prove or disprove it. All we have to do is LOOK AT THE PARTS. And of course I gave you the numbers related to spring tension. As little difference as that makes, I'd be surprised if HALF of the torque wrenches any of us use to build our motors with, are within 1.5 ft-lbs at 22. Although I'm always open to the experienced opinions of others who have done a thing more than I have.

Remember: 30 N-m is the REAL ACTUAL TRUE "spec", NOT "22 ft-lbs". That's the "standard" torque for that size hardware. Nothing special; just, they have to have SOME KIND OF setting to set their air guns or whatever they use to. It's only out to one significant figure, which in any scientific or mathematical endeavor (don't ask), that means that any number whose 2nd digit rounds either up or down to make the 1st digit a 3, is within tolerance. 26, 33.5, 29, you name it: if the 2nd digit rounds the 1st to 3, it's OK. If they wanted to be more specific they c/would have said "30.0" or the like, to indicate the need for greater precision.

Measure with micrometer, mark with chalk, cut with axe. Focus on what matters instead of being a slave to "spec" that you don't understand while pretending you're working at a level of precision that isn't even attainable in the real world.

JorgeG79

I know I have lots of learning ahead of me. This is the first time I do any internal engine work other than regular maintenance, installing long tube headers and a spindle leveling kit on my truck.

Anyways I thought I would know which rocker arms to torque first by looking at the springs that weren't compressed and start with that rocker arm. What threw me off was that none of the valve springs were compressed or moving at all when I would turn the crank so I didn't know which rocker arm to torque first.

G Atsma

You torque ALL rockers, some of which will be compressing the springs. Tighten all of them to the correct torque spec.
FIRST, learn the basics of how ANY internal combustion operates. Don't just go in blind figuring you'll learn as you go.

ddnspider

iTrader: (26)

But it's logic...

RB04Av

"Valve springs compressed" makes NO DIFFERENCE to the end result. Something on the order of 5% of the total torque on the bolt from absolute min (rocker loose) to absolute max (valve wide open). If you REALLY want to make the correction, torque rockers whose valves are full open, to 23½ ft-lbs, and ones partially open to somewhere between 22 and 23½, assuming you can even set your torque wrench to that degree of precision, and that it's accurate (precision and accuracy are 2 different things after all) to that level. Measure with micrometer, mark with chalk, cut with axe. If all you've got to cut with is an axe, and you're chopping firewood to fit in your fireplace, it doesn't matter if your micrometer's calibration certificate is current. Same deal here.

It's not that hard. Just logic and numbers.

Yes, BY ALL MEANS, use the factory "spec", if that's what makes you comfortable. No, the anti-matter will not meet the matter at the vortex of your driveway and annihilate the entire known and unknown universe into a micro black hole on the spot, if your particular torque wrench accidentally reads 22.76 ft-lbs when you let go of it. IT'S JUST NOT THAT BIG OF A DEAL. There's no gaskets, no parts that warp, no compressible parts, no tolerances, NOTHING, that are affected by rocker bolt torque, anywhere between "too loose" (comes apart) and "too tight" (strips threads and breaks bolts). Use the "standard" torque for that size hardware (30 ± 5 N-m), button it up, and move on. That spec - the "standard" one for 8mm bolts - has a built-in tolerance of a good 15% either way. Since that's all that # is, there's no point in getting all torqued up over it. It's JUST NOT THAT BIG OF A DEAL. Just like 35 ft-lbs on a 3/8"-16 bolt was for all of us for all those years... we whupped out our 9/16"-5/8" double box end and put a "standard" pull on it. It's JUST NOT THAT BIG OF A DEAL. They woulda used a different size hardware, with a different "standard" torque, if they'd thought that's what it needed.