My friend had this same issue I want to say he added a cam oil sprayer and they have a prob with the cam "walking" when you looked down in the lifter valley the cam wouldnt line directly up with the lifter bore. He was on a budget so he ordered a small hyd. roller cam and ended up running solid roller lifters since they can be picked up used for very little. It sounds crazy solid roller lifters on a hyd roller cam but sounds awesome and has been performing flawless.

 

Big Blocks with their canted valve have a tendency to eat valve guides. Often, the heads need rebuilt before the shortblock does. Bad guides can flatten cams, have they been checked? I think I'd look there first.

 

This can be an issue with some engines, where an issue is created by core shift, improper machining and/or by the improper addition of aftermarket components. Due to the taper the lobe has on a flat tappet style camshaft, the cam has a natural tendency to pull itself towards the rear of the engine and in doing so causes the lifters to spin, giving them the wear pattern they require. Typically the lobe needs to be centered with the lifter bore or damage to the lifter and/or cam can be the likely result. Some people install a timing chain with thrust bearing; either a Torrington Bearing or Solid Bronze to protect the front of the block, but without proper fitment can cause the cam to be pulled forward misaligning the lifter and cam lobe. Another issue that some create is with the installation of the rear cam tunnel plug by installing it too deep, pushing the camshaft forward. Even misalignment of the distributor can cause issues and generally shows up by a poor wear pattern of the distributor gear. Usually the distributor problems arise from decking of the block and/or cylinder heads without addressing the distributor pad of the intake manifold. It can be machined or by using a slip collar distributor, allow the end user to set the height to gain proper gear mesh. Roller cams, unlike their flat tappet cousins have lobes that are basically cut square instead of tapered and cam walk back and forth, hence their requirement for either a came plate or thrust button to hold them in tolerance.

Have the either of you pulled the valve cover to verify the offending lifter/pushrod is oiling? Have you checked the ends of the pushrods for bluing? If the ends of the pushrods are turning blue or galling up, they are not seeing enough oil and are burning themselves up. Usually Chevrolet engines do not suffer these issues very often being a pushrod oiled valvetrain, unlike some of the other manufacturer’s engines that oil the top end by some other fashion, unless some self proclaimed specialist inserts oil restrictors into the passages to limit oil to the top of the engine.

I hope you find your problem, but it is going to take investigation.

 

thanks for all the great info guys. I relayed the link to my old man, hopefully one of you hit on the issue. Does anyone know how to check a valve guide (with the motor still in the car)? As for removing the inner spring for break in, thats a great idea, but I think the next cam that goes in will be hydraulic, would that still be recommended?

 

You need to go to a roller setup, with the time and money you have already put into this engine. Are you willing to have the possibility of it happening again, and again?

EVERY flat tappet from every company will have this same problem, its truly hit or miss. Buy a roller setup, stop the bleeding.

 

It is odd that the same lobe is going out? What are the specs on the cam? I assume they are flat tappet lifters. Is it a small base circle cam or anything like that? I would pay special attention to the lifter bore, and make sure it isnt ovaled. How does the wipe pattern look on the valve tip? I assume you have checked to make sure the springs aren't binding, or the rocker isnt hitting anything like a girdle.

 

bigblocks are notorious for cam destruction on break in...i went through two with my 396

 

and what was the issue? did u figure it out? ......

 

as it turns out, the second time was the same lifter, but no the cam lobe, just a collapsed lifter. My father tore everything apart a few days ago, and found that the assumption of the lobe going again was incorrect. just a shitty lifter and a coincidence that it was the same one as the previous problem and same mileage / time to show the problem. hes getting another lifter and dropping it in and see what it does. I'll let you guys know if if happens again.