Boofers

I changed my cam & lifters in February and have since put on about 1000 miles. I pulled my intake off to investigate an elusive ticking sound, which I suspected was an exhaust leak between my heads and my exhaust crossover passage through my intake. This sound would only show up when the engine was under load, it sounded different from a loose rocker and I couldn't pinpoint it other than it was under the intake manifold.

While the intake was off I decided to have a look at my lifters and I found that 10 of 16 lifters did not appear to be turning. They have a solid straight line worn across the face. The wear line is shiny but you can't feel a difference in depth of the lifter surface.

I did the cam swap and set my valves in -10 degree weather. My hypothesis is that once all the internal engine components heated up and expanded the valves may have become too tight. With the valves set too tight maybe it prevented the lifters from turning??? My plan is to try to break in the cam again. I'll be visiting a local engine builder for his opinion. Anybody have a similar experience?

Surfer69

One thought is the lifter gets spun by the cam lobe surface angle which could have been messed up somehow, maybe wiped lobes, wrong cam? My .02

wcsinx

How's your lash look? Seems like if you'd set things up too tight, you would've wiped out some lobes by now. Maybe a bad cam? (like the last guy said)

Solid LT1

Mark any 2 lifters and place them face to face and check for convex radiuus on contact face (should be able to tell if faces are still convex with one against the other.) I would change cam and lifter set if they fail this check, you are on your way to total lobe destruction (flat cam.)

Boofers

Thats what I am afraid of. Thats a good test thanks.

gkvetteuno

Had the same problem on my 1971 L48. After the rebuild, I went through 2 cams before I realized some of the lifters were not turning. Both times I had the ticking sound. Readjusted the lash 4 or 5 times. Discovered the problem by marking the pushrods to see if they were turning, there were 7 which weren't. In my case, it appears the reason for the lifters not rotating was excessive lifter bore wear allowing the lifter to cant enough in the bore to neutralize it's contact with the taper on the cam lobe. Many machine shops have no way to deal with the lifter bore problem. I guess it requires special jigs ect. Some reccomended buying a new block. Since mine was a matching number 71 restored vert, this was not an option. Found a shop which built race engines and indexed lifter bores as part of their blueprinting. They drilled out the bores, installed brass sleeves and reindexed. I also changed cam manufacturers the third time around. One or both cured the problem. Hope your fix isn't this complex. It cost between $300 to $400 for the lifter bore work. Because the cam lobes were wearing down, I changed all the bearings as well.

Solid LT1

Usually a brake cylinder hone is sufficent to loosen up the lifter bores on a early block. The indexing of the lifter bores is a good but, EXPENSIVE proceedure to have done. I would check the new lifters going into the block, lubricate everything with Torco MPZ assembly lube and run the GM Enigne Oil Suppliment (EOS) for camshaft break-in. I would also run at least a 50% mixture of the Valvoline "not for street use" racing oil with high zinc content to protect my lifters.

Boofers

UPDATE - I showed my worn lifters to a local race engine builder. He said they are not that bad, that the cam probably doesn't have the hard outer coating worn off, basically I caught it in time. He mentioned honing the lifter bores. I think they are ok, there is no ledge in the bores, the lifters move in and out fine and turn easily. The theory I am going on now is I must have had my valves adjusted too tight. I decided to put in new lifters just to be safe. I will be putting it all back together this weekend.

Thanks for the break in advice, will do.

If I want to know if my lifters are turning - do the pushrods turn with the lifters?