Crane 1.6 rockers gone bad!

[SappySE107]

You don't have time to do it right? Well I hope you have time to do it again then cause that is what this is going to amount to. Like I said, your lobe can't be taller than your journal, or the cam wont fit into the block. Since you can only have it so tall, you must cut down the base of the circle to achieve more lift. You cannot get close to .500 out of it without having a smaller base circle than the stock cam has.

Do you have your stock pushrods? Throw the valvetrain together and tell me how far you turn the nut from having the pushrod spin but no side to side movement, and then tighten down the nut completely. I can give you a number based on those results.

[AaronGTR]

No, I have no time. I was trying to have this car running by friday because I was supposed to drive it to North Carolina for my brothers wedding. I didn't think there were going to be this many problems. And driving my grand prix on the mountain roads=boring... but I guess if I can't get it fixed right by then I won't be driving it.

I'm using the stock rockers, so no nut to tighten. I checked an intake and exhaust and tightened the rocker bolt until the push rod would still spin but I began to feel some resistance, and the cap in the lifter was about to move. I turned the bolt down then in between 1/4 and 3/8 of a turn until it stopped, and it was pushing in on the lifter. So it is getting "some" pre-load. I just don't know how much or if it's enough.

[AaronGTR]

So does anyone know approximately how much pre-load that is giving me, or how much pr-load you get with the stock valve train? How far do you tighten the rocker bolt between the beginning of resistance on the push rod, and fully seated?


I'm thinking if I can't get this thing fixed correctly by next weekend, I may just leave it apart and take some time trying to find some other roller rockers that will work. I know several people have alternatives to the cranes that they are trying. Most are aluminum though and I don't want aluminum again. I want stainless or chromoly so that the nose on the rocker will be smaller and they will fit without grinding the bottom of the LIM. If I find one of course, I'll be getting a checker pushrod and getting the correct length this time.

What I need to find is a SBC 1.6 ratio, full roller, 3/8" stud mount, narrow body, non-self aligning, stainless or chromoly rocker... is that correct? And then I still have to check them to make sure they fit correctly, line up on the valve tip right, etc etc?

Someone posted a link to these. http://cgi.ebay.com/ebaymotors/ws/eB...232118573&rd=1.
I have a question in to the seller to see if they are narrow body and non-self aligning because it doesn't say in the auction. They look a lot like comp's pro magnum rollers but a little different on the pushrod side.

I was checking summit racing too. Almost everything I found that fit the criteria was aluminum. I did find ONE comp rocker that matched all the requirements... except it's a ford and not an SBC rocker. http://store.summitracing.com/partde...1&autoview=sku.
Anyone think it might work? I can get them individually for $19 so it might be worth buying one to check it.

If I can't find a non-aluminum rocker that will work, I'm going back to the stock ones like originally planned.

[86euro]

Forgive me for my poor memory, but why can't the self-aligning type be used? Obviously, the guide plates would need to be removed.

[WrathOfSocrus]

In order to be self aligning they have tabs that insert into the head. I guess it might be possible to machine the heads for them, but in my case I am building a gen2 engine and already had the pushrod guides. I'm sure if you can locate the pushrod guides that it would be significantly cheaper and easier than machining the heads. Then again I'm not exactly sure how the self aligning tabs would mount and if the heads can be made to fit.

[86euro]

Are you referring to the tabs on the pedestal of the 3X00 rocker? The SBC's aren't setup that way, they have a standard stud and adjusting nut. The factory v8 rockers have little "bumps" on the tips that keep them centered on the valve tip. The aftermarket roller replacements usually have thin "discs" on each side of the roller tip to accomplish the same thing. It seems to me they would work for this application since they are sold in a narrow-body design for the centerbolt valve covers of the SBC. But, I've never tried it and don't seem to recall anyone else trying it before.

[WrathOfSocrus]

I'm only going by what I have read. I have pushrod guides so non self aligning was the ticket for me. I can't find the thread on the w-body forum I got the information from but was pointed to this link below

http://members.shaw.ca/betterthanyou...llerrocker.htm

I know it's a 90* reference but the thread on w-body said it would apply to the 60* as well.

What I do know is when the pushrod goes under tension from the cam trying to lift it, that the rocker arm wants to spin off sideways. To counter act that you need either pushrod guides or some sort of mounting built into the rocker so it doesn't twist and spit out the pushrod. Or a rocker shaft like my old 3.8 Buick had. The thread on w-body said to use gen2 pushrod guides for gen3 applications. I see on that link above how it has tabs on the rockers like you mentioned, but I don't know if that works with our setup. I already had the pushrod guides and was told that was the only way to go.


I never even bothered to look at the self aligning rockers until just now hahah. I honestly don't know why they wouldn't work with the tabs on the valve side, I was just told it didn't work.

EDIT - I can't find the original thread that stated it for the life of me. It mentioned something about grinding off some sort of 'ears' and I assumed it was on the bottom of the rocker like the gen3 stock style. Sorry for the misinformation.

[AaronGTR]

More info. I got my new pushrods yesterday. They are very nice (although I still don't know if they are the right length or not). Because of the different size oil hole and chamfer in the end, they appear to be possibly just a few thousandths longer. I checked the amount of turn on the rocker nut again and torqued them this time. I got a half turn on the intake rocker and 1/3 turn on the exhaust side, so slightly more pre-load than before.

Just for kicks I re-installed one of the crane rockers on an intake next to a stock one on an intake, and adjusted it with both of them on the lowest part of the lobe. The crane directions say to set pre-load with 1/2 to 1 turn of the nut past the point where the pushrod stops spinning freely. With 1/2 turn there was less pre-load than the stock side, and with 1 full turn there was more pre-load. If the stock side isn't even at the correct pre-load because of a smaller base circle, then I think I'd be correct in thinking I didn't have enough preload on the crane rockers and they all should have been set at 1 turn... so possibly they weren't getting enough oil flow. Hard to say. There's still the problem of the oil hole in the rocker lining up...


Here it's interesting to note the oil hole in the crane rocker is right in the middle, while the stock hole is offset towards the back.



Another interesting thing is the height difference of the pivot shaft. With the shafts lined up and the backs even, you can see how much lower the valve end of the stock rocker is. That means when they are both mounted on the pushrod and valve stem at the same height, the crane's pivot point is much lower and closer to the head.



You can see the height difference in the next two pics. You can also see how much higher and longer the nose of the crane rocker is, hence the reason they don't clear, and it would really be better if we could find a steel roller rocker. Anyway, as long as the ratio is correct and the geometry is ok, I don't think the pivot height matter a whole lot, but something else you might notice that could be a side affect is the angle of the pushrod to the seat in the rocker is different. It's almost 90 degrees on the crane, but close to 75 or 80 on the stock.




What does this mean for the oil holes? On the crane, the hole in the pushrod definitely lines up with the hole in the rocker at the bottom of the stroke, but it may or may not go completely out of line at max lift. Looking through the hole on the stock rocker, I can see that the hole in the pushrod is only half uncovered at the bottom, and at the top it is definitely out of line. So is it possible that the stock rocker oil hole is positioned to restrict oil flow on the up stroke and help add hydraulic pressure to the lifter, in addition to the oil holes in the lifter coming out of the oil galley? Or would it not really make a difference? I'm just wondering if using aftermarket rockers with the oil hole in a different position could affect the stiffness of the hydraulic lifter and possibly affect lift? Maybe I'm just being paranoid... but I want to fix everything so it works correctly this time and I don't have to do this again.

One other thing to note... if you look at the valve side in those pics, you can see how much clearance the roller tip gives from the spring retainer, but the stock rocker looks like it's sitting right on the retainer. I measured with a feeler gauge and there's only .005" between the stock rocker and the retainer, which means it's basically almost sitting on it and might contact somewhere through the stroke. I'm using comp titanium retainers, and I seem to recall that they looked like they sat higher at the valve tip than the stockers. I'm going to get out a stock retainer and install it to check, but it's possible that you can't use the titanium retainers with stock rockers.



The stock rocker is actually a bit wider at 1-5/16", than the crane at 1-3/16". The cranes are narrow body, so does anyone know how wide a standard body SBC rocker is? Just wondering if they are wider than our stock rockers, and if so by how much?


Other info just for the curious. The stock rocker/pedestal/bolt assembly weighs 242.9 grams, while the crane rocker/stud/nut combo weighs 203.2 grams. The crane rocker alone weighs 143 grams. You can't weigh the stock rocker alone, so no idea what the difference in actual rocker weight is, but it's obvious the cranes are lighter and will also remove mass from the engine. Also the new pushrods I received are 34.3/37.3 grams each int/exh, versus 35.1/38.9 grams each int/exh for the stock pushrods. Those pushrods are meant for a stock replacement of course, and not for guide plates, but they would cut some weight off the valve train for someone interested in high rpm.

[onefastV6]

I wish we could get someone to do some solid modeling, to determine the proper valvetrain geometry. I would love to see a set of after market rockers that would mount on a pedestal like stock.

[sprucegagt]

Hey Aaron, just for shits and grins would you mind doing this check with your old pushrods and the new ones with 1/2 turn preload. The actual method starts under paragraph "Finding Center".

http://www.circletrack.com/techartic...gth/index.html

[Monzsta]

If you look at the stock rocker, there is a "reservoir" tip that leads to the oiling hole, thus making alignment less critical. the pushrod contact point show this. the Crane doesn't have this, but judging by your pictures you should have good alignment anyway.

[3400-95-Modified]

I didn't see a direct answer but stay away from the bronze gear unless you can see wear on the CAM itself... The bronze gear is made to wear before the cam because a billet one will supposedly wear when used with a stock oil pump drive. So it is a replaceable part and made to wear out quick... I switched back to stock because I went with a regrind cam so I don't need it anymore.

As far as the whole pushrod fiasco from my stage 1 cam I needed .030 longer pushrods due to the base circle being smaller, GRANTED the stock pushrod length would have worked but I would have just had less lifter preload, so I measured the base circle difference stock to milzy and got my needed length increase from that. That motor ran like a champ and never had a problem.

Now when it comes to your LS2 springs there... I thought LS2 or LS6 springs wouldn't support over 515 lift?? And your coil compression for your noted .526 lift on that exhaust valve spring you pictured doesnt look like a lot at all...

hell this is 568 lift on my old LS6's with the lifter collapsing...



And here was a pic of my oil pump drive gear.

[AaronGTR]

Yes, I'm not going with the bronze gear. Somewhere here (I can't find it anymore) there is a thread with the original discussion about the billet cams and what gear should be run. There was a link Ben posted to an article talking about bronze and melonized oil pump drive gears and what should be used with what cam. It had some other info in it and it also talked about putting a groove in the piece right above the gear to provide extra lubrication. It was similar to this http://www.cranecams.com/?show=article&id=26. I'm going to try that, but I want to get a new stock cam gear first, so that next time I pull it I can see if it has noticeable wear on it or if it's ok. Problem is I can't find a part number for the oil pump drive gear. Guess I'm gonna have to go ask at the dealership.


As for the lift, I thought .550" was the most you could go with LS6 springs. I know I checked the clearance on mine and there are no issues.

[SappySE107]

If you don't care about longevity, then sure, .550 will work fine with LS6 springs. The more room before coil bind that you leave, the better.

Junkyard has plenty of stock oil pump drives and probably cheaper than the dealership.

[AaronGTR]

Well, since the LS6 springs are installed at 1.8" on an LS6 engine, and 1.7" on a 3400, if I add .1" to my lift numbers they would equal .54" int/.536"exh worth of valve lift and spring compression on an LS6. Since stock cam LS6 valve lift is .552"int/.548"exh... I think I'm ok.

Anyway, I checked all that out before I used 'em, and we aren't talking about valve springs here. The real issue is still the rockers. Summit should be shipping out the rocker I want to test tomorrow, so I just have to wait until it gets here.

As for the oil pump drive gear, yes I could get one from a junkyard. The one I have isn't about to fail though so whats the point of doing that? It's not really even that worn, it just has some wear patterns on the gear teeth face. The whole point was I wanted a new "un-worn" gear so I could see if the same wear patterns came back after doing the mod. I guess another option I could do is put the original gear back in and continue to test the oil for metal which could signal the gear continuing to wear. Right now I don't know how much of the metal in my last sample was from the gear and how much was from the rocker bearings. I'll just have to keep testing, and pull the gear again later to see if the wear has progressed or if the oil mod slows it down or stops it. If it doesn't seem to help, then I may have to swap the billet cam out for a regrind sometime in the future. Time will tell.