Macadoo

A little background:

71 CS w/ 350, 52k [maybe] original miles. tore it down and had the heads milled (don't have the specifics but it wasn't much) replaced exhaust valves, a couple intakes, guides, new rocker arms, new springs that match new cam, CutlassEFI (Erson) cam with 0.448 lift on both. I used OE shims for head gaskets, new double roller timing chain, fuel pump, and other goodies.

I thought I was hearing some valve train ticking so I pulled the covers and the rockers are tight, more than the recommended 25 ft lbs. All rockers are getting oil. Without pulling the rockers, everything looks okay. But I can turn the the pushrods with my fingers. Not all, but a lot of them (I'm assuming the ones on the base cycles of the cam). Should I be able to do that? They are the original pushrods, could they be worn? Does the beefier cam have a smaller base diameter maybe?
Thoughts?

Macadoo

Update: I can turn all the pushrods on the right bank except one. Not sure about the left, I covered it back up before I realized.

MDchanic

You normally can rotate the pushrods on valved that are not open, and you MAY be able to rotate pushrods on valves that are partially open if you really put some muscle into it.

If they all rotate with little effort, then I would wonder why, but if the open ones are all the way open (as measured with a micrometer), it would seem as though all of the parts are doing their jobs.

- Eric

Macadoo

No muscle needed, I can turn them fairly easily. There doesn't appear to be any slop but I can twist some of the rockers slightly, as in clockwise and ccw. But just barely, I can't really see them move, just feel them move. If that makes sense.

MDchanic

I would check to see whether all of the valves are opening the same amount.
You can measure them with a straightedge or something if you need to - they should move about half an inch.

If they're all doing that, then you're fine.

- Eric

don71

I don't think you should be too worried about this. They should spin a little.

If you are spinning these with the engine off a little bleed down in the lifters is to be expected. As long as you have proper preload, and sounds like you do, you're good to go.

Macadoo

Don makes a good point. It hasn't been run in about a week. I think I'll run it for a few and see if that helps. I don't have oil guards and i don't really want to trash my old covers, will it throw a lot of oil?
I do have a caliper with a depth gauge, that should do the trick for measuring.

To be honest I made a rookie mistake and put the intake on before bolting on the rockers so I couldn't see the pre-load. I just torqued them down and hoped for the best.

72 w29 all green

If i were you I'd check lifter preload; you don't need to remove the intake to do it. Just spinning pushrods isn't telling you much .

don71

If you've been running the kids to school and some joy rides too, I think you are good.

If it was something else, It would of showed it ugly head by now.

captjim

I agree. Also, just to add a little tip, always torque the rockers down with the valves closed. Not doing so can result in broken bolts and inaccurate torquing of the bolts.

Macadoo

I've been reading up on measuring preload. Seems easy....and hard. I'll see what I can do tomorrow.
Don, I've done a little more than that. A week after the 1st start we went for a holiday. Put 1000+ miles on it. She ran, and runs, great. During the trip I stopped to get the oil pressure tested (I have a gauge now) and the mechanic said i needed to set the valve lash. When I told him there was no adjustment he suggested retorqueing. Something had a slight tick but I'm not even sure it was the rockers. A lot of noise under that hood

Macadoo

Ran the beast for about 12 minutes this morning (with the covers on). Pushrods are a little tighter but still turn. Going to try and measure preload and valve movement now. Either way, I may just button her back up and drive until the weather gets bad.
FYI, I didn't hear any ticking this time. I did snug the bolts a little more first.

Greg Rogers

I put a cam in my 350 20 years ago and bought adjustable pushrods from Mondelo. I was never happy with that cam so a couple years ago I changed it to a "stock" type cam from Comp Cams. I also got some stock regular old pushrods and was not going to reuse the adjustable ones. When I put everything together I was told to make sure the pushrods went down into the lifters .030 when that cylinder was at TDC. It was way too loose with the stock push rods. I had to reuse the adjustable push rods. I think the base circle was smaller on this Comp Cam that on a original Olds cam. If you have lifter noise then that maybe what's going on.

TripDeuces

You can put one set of rockers on the base circle and then loosen the bridge bolts until the preload is all gone. Just make sure the push rod is still in contact with both the rocker and the lifter. Then you can just measure with a feeler gauge under the bridge stands for the amount of preload. It's not perfect but it will get you in the ballpark.

Macadoo

I've been wondering that myself. I may contact the fella that sold me the cam and see if he still has records. Unless it's on my sheet but I didn't see it. Some sort of code maybe?

Well hell Trip, where were you two hours ago? Lol, that's a better idea than what I did...and I'm not telling (it didn't work anyway).

I went ahead and buttoned her back up, went for a spin, smoked the tires here and there, then brought her home. Still the slightest ticking but just barely audible. Or I'm just listening too hard, I dunno.
My measurement for the valves was .45 but I can't be sure of my accuracy.
Oh, here IS what I found in an unrelated matter: my mileage had been slowly getting worse. It went from almost 15 to 11. Turns out the choke was only about 40% open after warming up (about an 8 mile stop-and-go drive, gauge read 180, it's usual reading). I'm assuming an electric choke is adjusted just as a non-electric? I loosened the screws and turned the face plate until it was all the way open. If it still works in the morning, stone cold, then I'm good to go.

MDchanic

OR, considering that the rocker pedestal screws are 5/16x18, you can loosen the screws at TDC, tighten them finger tight until you just get all the slack out, then count the turns until they are firmly against the heads; with 18 turns per inch, each turn is 0.0555", each half-turn is 0.0277", each quarter turn is 0.014", and each third-turn is 0.019", so if you are looking for 0.030" preload, they should go down a bit more than half a turn (since we're talking about hydraulic lifters, where you are probably good anywhere from 0.020" to 0.050", or even more, there is no need for this to be a precise measurement).

- Eric

Macadoo

Wise guy eh?

Sound like a plan. Question is then; if there isn't enough preload, then why not?

MDchanic

Indeed.

- Eric

BlackGold

Actually, the 1.6 rocker ratio factors in here. The valve-end of the rocker stays stationary, since the valve stays closed. As you tighten down the bolt, which is located at the rocker's pivot point, the pushrod-end moves further than the pedestal. So you end up with more lifter preload than the simple number of threads.

MDchanic

Oh crap. I think you're right.

I just did this about three months ago, and have a page of calculations where I worked this out, just to be sure... somewhere.

In that time, I forgot all about it.

- Eric