earl

Today I spent a couple of hours with the engineers at Web Cams. They are famous for their great reground cams. I have used the same Web reground cams for 2 seasons with no problems. They have been getting many requests for cams on a new billet. They have to buy their billets from Crower as do most all grinders. Suddenly they started getting the same cam breakage problem as Crower and others. Instead of blaiming it on Crower or the engine builder, they went to work to find the real cause. After cutting a vtec head in half and examining every little piece, they discovered the problem. There is a spring inside the lost motion sensor that was actually coil binding and locking the sensor solid. The only thing left to give was the cam. Snap. The reason for this happening was the change in geometry caused by the billet cam with it's large base circle. It was throwing the geometry off to the point where the sensor was being pushed down further into the head.
There are two cures available. One is to change to the Type R lost motion sensor. It actually has an extra .020" clearance. They even reccommend making this change when swapping to Type R cams. Most people won't do this as they cost about $30 each and you need 8 of them. Webs' answer is to grind their cam billet to a smaller base circle, thus putting the geometry into a position to not push quite as deep into the lost motion sensor.
They shared some of their future Honda projects with me but if I told you, I would then have to kill you...

filetofit

You would think that rather than buying type R lost motion assemblies you could modify the original ones. You could over bore the spring housing or you could cut a coil out and then stretch it back to it's original length. The solution would depend on the following.

Is the spring expanding too much under compression to fit into it's housing (bore the housing) or is it being compressed so much the solid height of the spring is reached (cut out a coil and stretch, changes spring rate).

PS The spring is probably pretty stiff so you'd probably have to heat the **** out of it to be able to stretch it after cutting.


[Modified by filetofit, 7:48 AM 12/14/2002]

V-SPEC 1

You're talking about the lost motion assy. right? hmm. So that's why the reason for all these cams breaking and most people are so quick of pointing the blame of the persons installing them, that they supposed to use this and do that.

Speed PHreak

<----- Who's glad he owns a non-VTEC, and also has known that you need R lost motion assemblies with the Crower VTEC cams "just to be safe" for awhile

BoostedB20VTEC - The reason people are braking cams is because basically the B16/GS-R lost motion assemblies don't have enough clearance to allow proper function. About the best simple explantion I can give.

VTEC = just something else to get pissed of at when it doesn't work.


[Modified by Speed PHreak, 2:54 AM 12/14/2002]

The_Head

I'm glad you posted this. Crower cams have gotten alot of bad rap in the forums here.

paulzy

iTrader: (1)

so how did you want to arrange my death?

SoulSurfer

Good information. That's something I didn't know.

senpai

Jared

earl, are you using an off the shelf grind or a custom?

earl

2 year old off the shelf. These all out gas motors have such a short piston life, it's hard to justify changing the advance/retard or run a bunch of different cam profiles on the dyno. Just too expensive for the non sponsored guys.

non-VTEC

earl: sounds like a valid point that you brought to our attention. but let me say this. if there isn't enough clearance in the LMA to accommodate the high lift/long duration of the crower cams then how do JUN and TODA and Skunk2 cams survive? i believe the TODA spec C and JUN 3's have bigger more aggressive lift/duration than crower's largest grind? (i think)

I'm not saying that your right or wrong i just feel that there may be a problem with the way that crower makes/treats/grinds their cores.

and we all have heard of other brands breaking as well. i can recall a few posts about JUN, TODA and skunk2 all having breakage issues. but is seems to be that crower is leading the way with this problem.

and just so you know i'm not bashing crower in anyway, i happen to be running on my second set of crower cams since my first set of NON-VTEC cam broke as well (exhaust cam, partial improper installation on my part )......

one thing positive i will say about crower is that i had good customer service with them. they warranty their cams for 3 years from manufacturer defects it says so on the back of the invoice directly from them. every-time i phoned Brian Crower and spoke with him directly he was very helpful and willing to resolve the issues ASAP and took care of all shipping and delivery fees of the old/new cams and components.

the only suggestion i cam make to anyone deciding to buy crower or any other aftermarket camshaft is to make sure to properly follow installation procedures, break in procedure, torque specs and valve lash specs. those who say cams don't really need a breaking period need to slapped on the side of the head. put a few hundred miles on the newly installed cams at-least before reving the **** out of the engine. make sure you follow what the cam manufacturer tells you for installation instructions.....

even though i sort of had a bad experience with crower at the time, i absolutely love the power/sound i get from them.......

earl

Remember, it's not the lift or duration that causes the breakage problem but the size of the BASE CIRCLE of the lobe. Web never had a regrind cam snap (smaller base circle), only new billets (larger base circle) have broke. Having said that, if the lift is to high in the cam lobe to the point you coil bind the springs, that can cause a cam to snap also.

speeds

hey earl, how can a billet broke? if it casting material it would broke in my opion

sweet

iTrader: (5)

earl, good info you brought to our attention. i've never used aftermarket cams before but have always thought about which ones may cause excessive wear or even break. i've heard many good things about Webcams, and the cams i hear about breaking/shattering the most would be JUN and Crower. also some interesting points from the rest who responded to this thread.

earl

It breaks because it can't spin properly so the only way it can go is up. When it trys to go up and can't, it just snaps. Does not matter if it is made from a steel billet or cast. Something has got to give. Hope that makes sense.

Suprdave

Totally makes sense...good thing my head alreayd has Type R LMAs.

Suprdave

boosted hybrid

A cool aspect of how the camshafts break in engineering terms is stress concentration factor. The actual lump on the camshaft causes the stress concentration factor to go up through a set of equations (i can post them up, but its kinda messy). When the stress concentration rises in the camshaft, moment and torque loadings from the combustion cycles become more prominent on the actual camshaft. Like earl said the camshaft doesnt have anywhere to redirect the stress, so the actual points on the camshafts between the lobes is where the stress concentration factor act. This is where you'll find the break occuring 9 times out of 10.

VaporTrail

All new ITR LMA's did not save my crower cam shaft/valve springs/retainers equipped motor. Neither did 700 miles of the break in process. The exhaust cam snapped in 4 places, 3 out of four directly across the center of the VTEC lobe. While some are saying nice things about Crower's customer service, I can't say the same. I was offered a second set of cams - like I'd want them! And what motor would I put them in? The damage destroyed the head and cracked the sleeves as well. I practically had to beg them to swap the cams for a set of rods. And their retainers? One broke while cruising in one of my customer's cars, wrecking the motor on his as well. This was with CTR cams! Brian's eventual answer to that was "oh, we've had some problems with our vtec valvetrain. I think the springs are too stiff". You should have seen the hell he went through to get ANY sort of compensation from them. Seems to me very few people know whats going on at that company, and I still think their products are crap from the word go. Just my experiences...


[Modified by VaporTrail, 12:47 AM 3/13/2003]

SiRkid

very cool stuff.
i myself was under the impression to change to itr lca's if i went for itr cams..hmm..weird .

earl

ITR LMA's have an extra .020" clearance over the GSR LMA's. That could be the diff in breaking and not breaking. They are quite expensive, however.

ninesecteg

I don't think the coil in it binds, just the moving assembly that hits the rocker arm. it could be shaved down if you take the clip off. I don't believe the l/m's are the real problem though. there are plenty of people running large cams(toda's,itr's,jun's) with no breakage! I'm leaning towards manufacture defect.

earl

When I say coil bind, I'm usually talking about valve springs. I do believe, however, that that is what happens inside the the LMA also. Whether it is Jun, Toda or Rocket's cams, a smaller base circle lobe gives more clearance from the LMA (lift or brand does not matter). I learned this from Web Cams directly, not thru personal experience.

b19coupe

I must be dense. I don't get the relationship between cam base circle and the lost motion assemblies binding. I can see where high lift cams might compress the LMA's beyond their ability to compress, but the base circle? Could you explain it more clearly so a simpleton like me could understand? By the way, I am working on building a head to run the Toda "D" cams, and valve spring coil bind is an issue that is consuming a lot of thought and time. The VTEC (mid) lobe on the intake cam has 12.9mm of lift, and most valve springs are not built to compress that much. Now you have me wondering if the LMA's will cause a problem too.

earl

For a better explanation, you might want to talk to Web Cams.
With a larger base circle, you can still adjust the valves to their proper clearance. However there is no way to adjust the clearance in the LMA so the larger base circle actually takes up the clearance normally built into it to account for cam lobe lift.
Best I can do on an explanation as I'm not the sharpest tool in the shed
BTW, I'm working on a project to come up with an answer to coil bind for high lift cams thru a different design for the spring and retainer but probably several months away from a solution.

b19coupe

I don't think that I buy Webcams assessment of the problem. The LMA is designed to compress ; if a cam with a bigger base circle is used, the LMA may be compressed a little when on the heel of the cam, but how does that cause the LMA to bind ? The LMA compresses a whole lot more when the lobe comes around, especially on a high lift cam. I think that the problem in the case of many of the cams that have broken is coil bind on the valve springs. The LMA theory is interesting though.