vortec rocker arm adjustment.

[smokeyco75]

I have what sounds like a rocker arm clacking in my Silverado. I know it isn't a T but this engine is used often in hot rods so folks may find this thread useful. I will be pulling the valve cover in the morning and assuming it is a bad rocker and not something more serious such as a bad lifter or bent pushrod or worse a rocker arm stud backing out I should be able to just replace the rocker arm, ball and nut and set the lash and be good to go. My question is this, is there anything different about these vortec heads I should know about besides them having self aligning rocker arms? Is the adjustment the same? I have built plenty of small block chevy but never worked with vortec heads before. Thanks for any help folks. Oh and yes it has the factory roller cam as well.

 

[bigblk1177]

Yep its the same!! Tighten down to zero lash and @ 3/4 turn more. Those vortec heads are the new double hump chevy heads! Cheap performance. Hope its not a worn cam lobe..

 

[bobs66440]

Double check to make sure it's not the pcv rattling. That happened to my buddy yesterday. He was ready to tear his engine apart. Then I yanked the pcv out of the valve cover and the noise went away lol! He was happy to say the least!

 

[railroad]

Check the valve spring while the cover is off.

 

[smokeyco75]

Well I am pretty sure it's not a rocker arm issue. I removed the valve cover and then started it up and let it get up to temperature. No clacking. Checked the valve cover for signs of contact and there is none. I removed each rocker arm one at a time and checked for any abnormal wear as well as checked for bent pushrods and they all look good. I got to thinking about it and realized that usually a rocker arm clacking due to being out of adjustment or worn would usually clack all the time. This is intermittent and usually goes away after it is running for a minute or two. Yesterday though the clacking was constant. Now of course there is no sign of the problem. I checked everything i could on the outside of the engine for anything that might make a noise like that and all looks fine. I am starting to think I may have a bad lifter. This is a high mileage engine with 197,000 on it. I'm going to put the valve cover back on and run it a while longer and see if it gets worse. A cam and lifters for this thing is over 400 bucks so unless someone knows an aftermarket flat tappet cam that will work with this fuel injection I'm just going to run it until it blows and then put in a replacement engine.

 

[smokeyco75]

I forgot to mention that I found the distributor cap just sitting on the distributor. Not even screwed down. I guess the guy I bought this truck from forgot. How it ran I don't know. Interestingly enough I changed the oil right after I bought it and the oil pressure went from twenty pounds at idle hot to thirty four pounds at idle hot. Max pressure is 62 pounds hot. Pretty good considering the miles on it.

 

[RPM]

200,000 miles, they don't make em like they used too. We are glad they don't. Used to be 60,000 was about time for a overhaul.

 

[bobs66440]

200,000 miles, they don't make em like they used too. We are glad they don't. Used to be 60,000 was about time for a overhaul.

Yep, 30,000 was a valve job at minimum...

 

[smokeyco75]

Well I got it all back together and drove around town some. Had several stops in my trip and at every restart I heard no noise. I doubt it is gone for good. When I adjusted the rockers I did go about 1/16 of a turn snugger than I normally do but I usually set them a touch loose in the stock car motors I built in the past. I will report any results of my efforts in the near future if the clacking gremlin returns.

 

[railroad]

I had a 300K mile engine do the same thing. I pulled the valve cover and adjusted the rocker off while running and let the lifter pump up completely, then adjusted to quite plus 1/4 turn. It tried to do it again and I ran a bottle of ATF a couple 100 miles before an oil change. It ran good till I sold it.

 

[Screaming Metal]

Probable a lifter failing to pump up because of some sludge. The ATF will work, or some sort of motor cleaner. Riselone is good, if you use a little of it. Use it too strong and you'll stop up your pump screen. It'll wash all that sludge from the valvecovers down into the pan....
As RR said, the ATF will work, is way milder. You can even use some diesel fuel....just not much for very long....

 

[smokeyco75]

Good point on the buildup. I was surprised at how clean it was under the valve cover. Heck it looked like a new engine should.

 

[Screaming Metal]

I remember back in the 70's and 80's, you'd pull the VC's and Holy Crap.....it looked like tree bark in there, all that caked on burnt sludge....You could always tell when they didn't change the oil like they should. OR....who ran STP.....hahaha....
A sign of the times....

 

[smokeyco75]

The guy I bought the truck from told me it had synthetic oil changes every 3-4 thousand miles all its life. The mileage written on the oil filter says it was changed 10 thousand miles ago. I never believe a seller anyway. So far still no clacking after about two hundred miles today.

 

[bobs66440]

I'd call it fixed