Wiped 3 lobes

[Morley]

Long story short. My rockers began to tap..loudly on the way to work. On the way home (10 miles) I got popping back through the intake. These are classic symptoms of a flat tappet cam going south.
Now this cam had been for 40k miles without being disturbed since break in. I found 2 lobes completely flat, 1 lobe going flat and 3 cupped lifters. The oil pan and filter had metal dust in them and other lifters were internally locked up from metal dust.
I searched around for a reason why, after that many miles the cam decided to go out. This is what I found http://www.hotrod.com/techarticles/e...ech/index.html
It seems that through a mandate from the EPA the oil co's changed the formulation of engine oils and removed the zinc and phosphorous. These are anti-wear additives that were in the oil until about 3 years ago. It turns out that flat tappet cams NEED these 2 additives to survive and the oil co's probably knew it. But they didn't let it be known that their products may destroy your engine's valvetrain.
So, if you have a flat tappet cam Crane reccommends that you use Shell Rotells T oil (diesel oil) since there is plenty of zinc and phosphorous in it, because the diesels require it for all of their rotating assemblies.

Cam was replaced with a (bigger) Lunati Voodoo cam.

[Genopsyde]

thanks for this post, I have a flat tappet cam now too. do you think this is a problem with synthetic oils as well?

[1986Z28]

shouldnt be a prob with synthetic, as long as you didnt break in the cam and engine on synthetic!

[Genopsyde]

oh no, break-in is beyond done.

[Morley]

I broke in my cam/engine on dino oil and ran dino for the first 25k miles, then switched to Mobil 1. The problem was the first 25k started the irreverseable process of wiping out the cam. Once the cam lobes start to go there is no stopping it, though the Mobil 1 probably slowed the process considerably. The good part of all this is that Rotella T is only about $9/gallon, is a name brand oil and is reccommended by cam mfg's to extend the cam's life.

[poormillionaire2]

What exactly is a 'flat tappet' cam?

[Morley]

Originally Posted by poormillionaire2

What exactly is a 'flat tappet' cam?

They were used in pre-1987 vehicles. The lifter has a "flat" bottom that rides on the cam lobes and they in turn move the pushrods to tilt the rocker arms which open/close the valves.
From 1987 on the cams employed a roller lifter, which as the name implies, has a roller that rides along the cam lobes. The result is almost no friction between the lifter/cam, steeper cam ramps and the ability to rev higher.
On a flat tappet if there is insufficent lubricant between the cam lobes and their lifters the lifters and cam lobes begin to wear, rapidly. And once the hardened surface of the cam and lifters are worn through the lobes go flat and the lifter surfaces become scalloped. One of my lifters was worn so badly that it was almost 1/8" shorter than it should have been.

[jveik]

yeah i know that story all too well. i had a huge cam problem in my old 350 that caused the death of many power valves in my holley carb due to backfiring through them. hopefully ill be a little smarter with my 383 stroker and not do 60 in first gear all the time in an attempt to throw a rod... the cam will go first more than likely unless you really rev it and if a rod never does fly, your stuck with a running engine with a crappy cam lol and no excuse to buy a new engine...

[poormillionaire2]

Ok, thanks Morley. And since were on the subject of cams, I have another noob question. But I know some of the answer.
What is the difference between a hydraulic and solid roller cam? And why are solid roller cams sometimes given the nod over hydraulic setups?
I know that solid rollers require more maintanence as to adjust the rockers and such, but how do they put out more power and rev higher?

[Morley]

Originally Posted by poormillionaire2

I know that solid rollers require more maintanence as to adjust the rockers and such, but how do they put out more power and rev higher?

Solid rollers are "mostly" used on track vehicles. They make more power because they can run VERY steep ramps on the lobes allowing the valves to open and close very quickly without floating a valve. They also allow the use of very heavy springs which also keep the valves from floating at high RPM's.
The down side to all of this is faster cam/lifter wear...not to mention an idle that just won't get it on the street and little or no vacuum at low RPM's.

[Blue Bowtie]

And, FWIW, once a solid roller is adjusted properly, it requires adjustment a lot less frequently than a solid flat tappet setup. You can probably go two years or more of average driving (30,000 miles) on solid rollers before any attention is needed. Solid flat tappets might need adjustment every 6-15,000 miles depending upon the setup, cam lobe profile, and type of use. Chrysler Crooked-Sixes used to use solid lifters, and no one ever adjusted the valves. You could usually hear them coming down the street from a block away, and pick them out over all the other traffic.

[poormillionaire2]

What exactly is meant by 'hydraulic' and 'solid'?

[silicon212]

Hydraulic lifters have a plunger in them in which the pushrod rides. There is a spring between the lifter body and the plunger, and this area fills with oil under pressure from the lube oil system. Since oil does not compress, it can be used to fill up the free space (the lash) between the pushrods and the valves, making for a quiet system which needs no periodic adjustment.

Solid lifters are just that - there is no plunger as the pushrod rides in the lifter itself. As there is no hydraulic provision to handle the lash, you must adjust the lash manually via the rocker arm and this adjustment must be made cold, with a predetermined amount of lash so the valves don't get held open once the engine warms up. For this reason, solid lifter engines are noisier than hydraulic lifter engines, and if the lash is improper, they can be very noisy.