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-   -   What could be binding? Camshaft? Nope. (

BroncoBuck 11-22-17 11:38 AM

What could be binding? Camshaft? Nope.
I posted a bit earlier, about not seeing any oil coming to my valve train, as evidenced by spinning a drill in reverse, stuck down the distrib hole, running at 400RPM. Saw the oil when I put the engine together, now I am (was) not. But I did see oil in the valve cups, which was weird.

All along, what I've been trying to find out is why my valve train is so clacky (sounds like a train hurtling down the tracks, about to come off the rails, CLACKETY CLACKETY CLACK!!). And, I have a low "knock", but it was only every OTHER rev of the crankshaft. I thought all along it was because something was wrong w/ the crankshaft, so I took the engine out, then put a socket on the crank and turned it around and found out it bound up hard, every TWO turns of the crankshaft! "Oh oh", I thought, the camshaft is bent. I took out the camshaft (carefully!) and inspected it. Perfect. It's like it's brand new. Bearings all intact and not scored. I pulled off the valve rockers, rods, lifters, and spun the camshaft in its hole. Perfectly smooth. Lifter rods checked on a sheet of glass, all perfectly straight. Inspected the rockers, they all good great. That leaves the valves themselves and the lifters as being culprits for a once-a-rev bind-up on the camshaft. I haven't spent the time yet to figure out which valves are compressing when the camshaft binds up, but I'm about to this weekend.

I got on top of the valves and depressed them w/ a rubber mallet (by pressing down hard, not whacking them!) and I have to say, a fair significant amount of them, all exhaust ports, have an initial "sticktion" to them. They bind for just a sec, then "break loose" and the valve travels great. All the valves and guides are new, I just had them put in. The heads were professionally done by a machine shop.

Ramble ramble....

Question #1: IS an initial sticktion okay for a valve? Especially if it might not have seated yet? I can press the valves down smoothly, it's just the initial sticktion that is concerning me.

I took out all the hydraulic (roller) lifters and tried to compress them. I don't understand them very well. I shouldn't be able to slowly compress the oil out of them, right? My thumb pressure is nowhere near 45PSI (I guess?) and if what I understand is right, the valve springs' PSI of ~200 beats the oil pressure's PSI of ~45 and DOES compress them. But human thumbs do not. I took several of them apart and inspected them and none of them are filled with gunk (they're all new, too).

Question #2: Still looking for an explanation for a once-a-rev bind on the camshaft. Can't really test the hydraulic lifters with the engine out of the car, because I don't have adequate PSI to pump the lifters up. Do I try spinning the drill in the distributor hole until I see oil come out of the lifter rods, and then try turning the crank? Or, do I buy a solid lifter, stick it in the hole, and try THAT, per cylinder, to see if my valves are binding up?


CatSkinner 11-23-17 06:08 AM

Re: What could be binding? Camshaft? Nope.
I'd think by throwing in solid lifter, you'd only cause what ever's binding to break quicker. It'd get you to fixing the problem quicker, but it'd likely have collateral damage. Hydraulic lifters provide a little shock absorption and a smoother valve train. The stickiness of the valves could be due to their lack of lubrication. A lot of what your problem may be is strictly a loss of oil flow. I hate to say it, but you may need to pull the pump. Try spinning the pump without the oil filter on, see if you get flow there.

Big Block Ford 11-23-17 11:10 PM

Re: What could be binding? Camshaft? Nope.
I'm with skinner on this. You need to check the oil pump out.

Make sure the pickup is secure and sealing on the pump and check the pencil drive is in good shape too.

The binding every second turn of the crank is a bit trickier but it may be valve binding like you have found. That could be from lack of oil.

BroncoBuck 11-24-17 10:13 AM

Re: What could be binding? Camshaft? Nope.
3 Attachment(s)
well... pulled apart the bottom end of the block, and was dismayed to see the bearings are all looking funny. Not spun, or burned up, just with shiny stripes on them. Don't have the experience to know what that means. The camshaft looks okay, no worn spots, but the crankshaft has striations on it. When you scrape it back and forth with your thumb, you can feel ridges. With the micrometer, each bearing surface on the crank checks out to be exactly 3.000" or 2.999" (one or the other), but no variations beyond that. And yet, I can still feel the striations. I haven't torn apart the heads and cylinders yet, but I suspect I'm going to have to. Damnation. I just had this done 2 years ago. It IS looking like the oil pump failed. Melling, brand new. High volume, too. I'm beginning to suspect the machine shop that did my block forgot to blow out the oil passages?

Even with the striations, there is almost zero play in the components when they're bolted together.

here's some pics.

CatSkinner 11-25-17 07:08 AM

Re: What could be binding? Camshaft? Nope.
First, unless there's a high spot on the bearings, I wouldn't worry about them too much. The fourth one from the top looks a little strange, but I think that's just the light reflecting off of it. With the crank, I'd hit it with 600 then maybe 1000 grit. Having a thousandth or two groove won't hurt you as long as there's nothing high... unless you plan on building a 1500 HP fire breathing monster capable of 7 sec quarters with nitr... sorry, I digress. For typical street application, mild or on the hot side, I didn't see anything that needed to be tossed, just dressed. The bearings, I wouldn't touch as the bearing surface is too soft to want to redress, unless you have high spots. If you do, approach carefully. You've probably only lost a few thousand miles in their life, at best. My concern would be clearance change or warping. I prefer a double check method. The first you've already performed to what it looks like, calipers and mics. Second is Plastiguage. I've sent a link explaining how it works if you've never heard of it. It may seem hokey, but I used the stuff while I was doing repairs on Navel Nuclear Submarines. If it's good enough for that application, it's good enough for cars. Once completed, I'd clean everything with Gunk's water based degreaser or something equivalent. I prefer water based as you can use it with hot water, and in flushing/rinsing, clean, water's pretty cheap. Air dry, then coat everything with oil.

Genuine Plastigauge - How It Works

BroncoBuck 11-26-17 12:49 AM

Re: What could be binding? Camshaft? Nope.
Finally, somebody who talks an ounce of sense. I called this one machine shop and told them I had this engine where I had some high spots on the crank and wanted them turned out or finished out. The guy said, "woah woah woah, hold on, we don't do any engine work unless we blueprint the entire engine. We'll turn that crank but we're going to need to measure *everything* and cut that crank and hand-match each bearing individually. we'll order them individually and match the tolerances, it will take about a month, and cost several thousands." I said, "All I want is to take the high spots out of the crank so they don't wear on the bearing, the tolerances are already okay, I've measured them" (with plastigauge). He wouldn't hear of it. Especially for an engine I'm going to put in a rig that I can't sell for more than $4000, tops (or so I think, it's going into a relatively nice '96 Bronco)

CatSkinner 11-26-17 09:26 AM

Re: What could be binding? Camshaft? Nope.
The high spots on the crank shouldn't be part of the shaft. More likely wear material, carbon, and maybe a little bit of the bearings. Pay special attention to the bearing surfaces (we only got a pic, you can feel them). It's likely to be relatively soft and mildly bonded with the shaft. Should be easily removed.

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