http://www.chevelles.com/showroom/flat2.JPG


FOR ANOTHER VIEW OF THE LOBE (http://www.chevelles.com/showroom/flat1.JPG)


The bad news, one lobe flat and 2 headed that way!!!

For the first time in my life I have wiped a cam lobe!!! Despite a proper run-in with assembly lube and 2000 RPM breakin. My only possible fault was not removing the inner springs, so scold me if you wish, but I've never, ever had this happen before!!!

During the breakin after about 5 minutes of running time me and my buddy noticed a slight change in exhaust note but didn't think much of it at the time, little did we know till we tore back into it today!!!

So, the bad news is I'm out a couple days work and a couple hundred dollars, the good news is all is well now!!!

We immediately changed the oil and filter, stabbed the 276/286 back in at the straight up marks and put it back together. Ol Paint is very happy with this combo now!!! Went for a test ride and I loaded it down like before when it would have been pinging big time it starts nailing me back in the seat!!!

A hard earned lesson but a well earned lesson!

well that explains the poor performance of the solid lifter cam. I would not just stab another cam in with out completely cleaning the cam guts out...I have done it...but got lucky...its a crap shoot..good luck

OUCH!!! :eek:

BigJim.....

The cam is under warantee, send it back to me and I'll see what we can do. Probably another one just like it, but I don't know, as this is my 1st warantee at Lunati....

UDHarold

Originally posted by UDHarold:
BigJim.....

The cam is under warantee, send it back to me and I'll see what we can do. Probably another one just like it, but I don't know, as this is my 1st warantee at Lunati....

UDHarold Thanks Harold!

I did check the cam install as you suggested and the intake was in the correct relationship to the exhaust as you described. I honestly don't know what happened. I thank you for your offer. I'll send it back and if they'll cover it fine, send me another one and I'll sell it to someone to recover some of the expense. But if not, no problem, I'll get over it.

I'm here to tell you though Harold, that 276/286 set straight up has really set this thing on fire!!! It pulled pretty good in second before, I thought, but now it's really pushing me back in the seat from about 2000RPM up!!! And no pinging at 37 degree total advance. It still has a tank of 95 octane but I'm confident it will work with 93 even if I have to cut the timing back a tad. Stupid me should have tried that instead of the new cam.

So for those who inquired about buying the cam before I found out it was trash, I may still be able to make a deal.

I am confident it would be a good cam for some combinations but not mine. My buddy and I have decided that Ol Paint has a very picky combo and will spit anything I do to it right back at me if it doesn't like it!!!

posted 06-23-2003 10:53 PM
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The reason the lifters spin is that the lifters have a 35" radius on their bottoms, and the cam lobe has taper on it. Most after-market cam companies use 'double-taper', about .0015"-.002", to ensure the lifter is spinning.
This is on both hydraulic and solid lifter cams.
The main cam/lifter problem causing wiped lobes is having the cam too far forward in the engine. There should be less than .010" endplay in the cam, and I prefer .006" to 0.000" as best.
The next reason is too much spring pressure on the nose for the cam design. Pointy-nosed cams have very sharp radii(that's 'radiuses' spelled correctly) and cannot tolerate high nose pressures at break-in. The next thing is not enough molydisulfide(MOS2)on an individual lobe.
Other reasons are inadequate valve train clearances. Too much pre-load comes in this category.
Solid cams are more often put in by more experienced engine builders, and may have less problems because of this.
A lot more hydraulic cams are sold, and many are sold to first-time installers.

UDHarold

Although it's too late i thought i would post this very good info by UD.
I'm wondering if that cam is considered a pointy nose came and if taking out the inner springs would have let the cam break in properly??

I'm not trying to start any trouble, i'm just wondering why we are seeing so many cam failures.

I'm glad your at least happy with the old cam and new setting, i just hope you don't see any damage form the metal now in the motor.

From all the cam failures it looks to me like it's well worth the money to index the lifter bores and go with a roller even on a street motor.