Valve problems...

[4GSixty3]

Alright, I took all valves, lifters, rockers, everything out of my head and cleaned my head real good. I cleaned all lifters, valves, etc with carb cleaner and lubed them up with wd-40. I made sure to blow out all fluid from the lifters also. Well, today I put my exhaust valves back in along with the cam itself. I rotated the cam after i got everything tightened down and I noticed something strange. When the lobes are hitting the rockers, my valves are going down but when they go up, they dont close all the way. When they go down in another cylinder, the first valves are not closing all the way and that goes with all 8 valves. They are not seating right or something. Im thinking maybe I just got to take the cam out and rotate it around another turn but I'm unsure. What could be causing all 8 valves to not seat back into position and stay open like 1 or 2mm's? Any help would be greatly appreciated b/c I'm stuck.

 

[defrag010]

It sounds like your lifters need to be bled again. How did you bleed them? You need a bench vise to really get them good enough to get all of the oil out of them.

I'm going to go off on a tangent, though, and say that you probably caused more damage than good by doing all of that. Each valve has to have a certain installed height for the seat it's setting in. If you take out the valves and don't put them in where they came out of, your valve stem installed height will be off and it will mess with your valve operation. Also, the valves will seat themselves in their particular valve seat, and if you switch them around, you could cause some serious sealing issues. Even if you put them back in the same seat, you are likely to have sealing issues and low compression.

 

[4GSixty3]

Hmm, I did put all the valves back in original places but maybe your right and they still will not seat properly. As for the lifters, I just soaked them and then blew through the holes on top to get the oil out. So I just put them in a vice and compress them?

 

[defrag010]

yeah, when I worked at a head shop we'd bleed them by clamping them down all the way with a vise about 5-6 times, or until oil stopped coming out when it was compressed.

 

[Defiant]

Has the engine been run to pump up the valve adjusters?

Oh, and WD-40 isn't nearly enough oil to start your valve stems in their guides with.

 

[4GSixty3]

Ok thx alot defrag010. Defiant, the head is still out of the car b/c I'm rebuilding bottom end so there is no fluid in the lifters right now. You think when I fire it up, they will go back to normal? O ya, another thing I was thinking of was when I put the head back on, I need to turn the exhaust cam gear a little bit anyways so that could be the prob too. As for wd-40, I just soaked everything after I cleaned it all with hot water and baking soda so no rust or anything would form but I didn't lube the valves up with anything when I stuck them back in, just the stem seals with oil.

 

[BISHILVR]

are you sure your valves are'nt bent???...don't even THINK of starting that thing up with the valves like that!!!.....but even if you did install the valves in the wrong holes you would'nt have this problem because they are all the same length within a couple thousandths and the lifters are there to take that up...so i'm sayin you have a real problem somewhere, i dont know why you cleaned the valve train with water and baking soda???......not a real good idea bro'..........just pull the lifters back out and stick a small brad nail or somthing that will fit, into the hole in the top of the lifter and at the same time "pump" the lifter up and down until all the water, baking soda mixture is out of the lifter, then try that and see what things look like, and from now on leave the baking soda to the cakes and brownies................

 

[4GSixty3]

Have you ever used baking soda to clean anything? I used this mixture on my bare head and the thing looks like it came straight from the machine shop. I wasn't too worried about cleaning all my parts with what I used seeing as I have 3 heads at my house so it's not like I needed it but it turned out very good so I'll stick with this method from now on. I have actually used baking soda/ water on everything down to the bare block, works better than engine degreaser, IMO. Anyways, I know the valves are not bent b/c this head came off a running car but last time I checked the clearance issues, they were almost normal so I think I should be fine now. But to be safe, I will probably pull the lifters back and and compress them in a vice.

 

[pinknuggit]

a..but even if you did install the valves in the wrong holes you would'nt have this problem because they are all the same length within a couple thousandths and the lifters are there to take that up...

With new valves, yes, but the lifters can only compensate for so much. There is a threshold with which the valve stem installed height should be, and if you've ever had your valve face ground or valve seat cut, your valve stem installed height will definately need to be changed. Too much height, and you will have valve float with higher oil pressure, and too short of an installed height will cause your lifters to fail. It's the same principle as camshaft regrinds. I used to work at a cylinder head shop also, and for fun, we'd tap the feed hole for the lifter, screw in a tiny fitting, and send about 150 psi of water pressure through it. It would Pop the top off of the lifter and shoot hard/high enough to put dents in the tin roof that was about 40 feet high!!!! :laugh: (good times)

On valves that have been run in a head for over 100k, there is more than likely a burr or mushrooming on the valve stem tip, which decreses the installed height. The only solution to this is to have the valve face reground or get new valves. I would Never EVER put a head back together unless I had a valve stem mic to check installed height, and without having the face/seat machined. With doing that, your valvespring installed height will change also, and you need a tension checker so your spring pressure will be in spec at a given height. With this comes the wonderful world of shimming the springs..

4gsixty3, I would reccomend taking your head to a headshop to have it rebuilt, because just cleaning it does absolutely nothing to renew the tolerances and clearances. All you're doing is reassembling a worn out head, and it will be exactly the same as when you took it apart. The head shop will do alot of things which you're neglecting, such as replacing worn valve guides, surfacing the head, machining valve seats, grinding the valve faces, setting the right valve stem and valve spring installed height along with proper spring pressure at the given height. If you'e gonna do it, do it right.