I drove the car yesterday for about 350 mls and when i was almost home i heard a knocking sound coming from under the valve cover(drove back home the last 50 mls carefully) I opened up the covers and found 3 broken rockerarms 1 on the driverside and 2 on the passenger side and the valves where damaged also from the rockers Is this normal that the rockers can break What is the best place to get new rockerarm and shaft assembly's,valves and gaskets from. thanks wilfred
There is a set of rockers on Ebay from Maddog Racing for $176, they also stock other nailhead parts, and complete engine kits. Have all the rockers broken in the same place? is there sufficient oil getting to the rockers?
It's very unusual for this to happen. :shock: Have you recently done work to this engine? I'm thinking along the lines of COIL BIND. That's when someone piles shims under the valve springs or ignores the installed spring height during a rebuild.......particularly if you have installed a hi-lift cam. o No:
the heads where rebuild about 3 years ago,just lifted one off,valves are all damaged on the tips,combustion is good. I'm thinkin about contacting ta performance for the new valves and rebuild rockerarms and shafts and a gasket set. Or is there a better adress for the stuff i need?? Does someone have an email adress for ta performance?? Now i'm going to pull the other head off(wish me luck) The complete engine was rebuild,.030 over and a stock cam,with stock valves and springs wilfred
another qeustion if i should diside that i use rollerrockers from ta performance,than i have an oiling system true the lifters and pushrods,is that better than the oiling true the shafts??? Is there a possibility that the rockers couldn't get oil to the tips?? all of the tips are worn in about 16000 mls???? any suggestions??? wilfred
what is the best way to improve the oiling system to the heads and rockers??? I think that my rockers did'nt get oil to the tips and are broken for that reason
There are oil feed holes in the rocker shafts, one for each rocker. The holes have to point downward to work properly. If they are pointing upward, they tend to hemmorage and may not have oiled the tip. If you go with the TA roller rockers it will upgrade you to pushrod oiling which will solve the deficiencies of the oil filled shafts. Normally, a good set of stock rebuilt rockers should be fine, but because you had problems, try to determine the cause. Coil bind could definately be a culprit.
I agree with Dave, also what could have happened is that the rocker arm shafts are plugged with sludge and starved the rockers for oil. Every time I tear down a nail head I break down the rocker arm assemblies and swab out the shafts with a rifle cleaning brush and solvent then blow them out with compressed air , reassemble them with new plugs and plenty of lube.
Coil bind is when the valve spring compresses completely before the valve achieves it's full lift. So there is a physical binding and something has to give. Usually the rocker or pushrod fail. You will also want to see if your pushrods are bent. Easy way to check pushrods is to roll them on glass (one of the windows of the car) and watch the shadow. If the shadow changes dimension, the pushrod is not straight. Worst case scenario for coil bind was this weekend for Del Worsham and his NHRA funny car. His inner valve spring went into coil bind and somehow the valve broke. Because of this and all the other things that occur when this happens to a supercharged nitro engine. The engine exploded and blew the car body into a million pieces. I guess coil bind makes for good TV!
how can they bind if everything in the engine and heads are stock,the engine run 39 years without a problem and now after 3 years and 15.000 mls it breakes aparto No: and here is another engine that is a 364 rebuilded in canada 35.000 mls ago,broke off all off the rockers and 2 valves dropped in the cylinders.
Depends if it was worked on. It is tough to get the right springs for a nailhead. If there is that much time on these engines then they fail, could be oil issues, not only does the oil lubricate the moving parts, but cools them. Yes, the valve springs create heat. I think nailhead rockers break more often then people think. They are also very close to the spring retainer, so if contact occurs, maybe because of a change in valve tip height. Not sure if a rocker breaking will cause a dropped valve, but coil bind definately can. Nailheads are also known for sticking valves. If your rockers that broke were all for exhaust valves I would investigate that as well. It's one of those things that you just need a trained eye to look at it. Normally, there will be signs of rubbing, accelerated wear, etc.
the tips from my rockers where all worn when i looked to them that wasn't 3 years ago. the valve tips are all worn. I think that i had no oil to the tips and only to the pushrods.that's why i think the tips worn and broke 3 off the tips and then broke the rocker because they are cast aluminum. maybe it's time for rollerrockers and a hi performance oilpump,new valves and valve springs????
Could it be that when they installed the heads and headbolts and coated them whith loctite, that they accidentaly closed the oilholes to the rockershafts or a portion of them????
Hopefully they didn't use loctite on any of the head bolts, that could be ugly trying to get them out. The front rocker stand bolts are the ones that have the oil flow around them, it would be tough for them to block off with loctite on the threads.
The only sealer required on "NailHead" head bolts are the 3 that go into water under the valve cover/rocker arms. If in fact silicone was used on the rocker shaft bolts it blocked or partially blocked the oil feed holes, cause of your problem of NO OIL!!!!!
One more thing I've run into on these engines........the spec for valve stem height of 1.540".......plus or minus .050" ......is VERY IMPORTANT. Your valve spring retainers will contact the rockers on the underside if the seats are overground. Usually resulting from having new guides installed that are replacing factory guides that were non-concentric. Some are and some are not. I wish I know why Buick let heads go from the factory with non-concentric guides, but they did and machinists who press in new guides that are concentric and are not familiar with this problem have no choice but to overgrind the seats which results in valve recession and therefore require a lot of shims under the springs to keep the spring height spec. Now the springs end up installed crooked in relation to the spring seats, and the stem height ends up way out of spec. Rocker arm contact area to the valve stem is thrown off also. If the stem tip gets ground too far to compensate, to respect the 1.540" spec, it may weaken the retainer area of the valve. That's why I say sleeving the factory guides is better. A machinist with good intentions may make this mistake and not even know it. Just my observation, that's all. :Smarty: One more thing.......perhaps your guides were sticking out too far and the spring retainers bottomed out causing the rockers to break. NAPA did that to my heads, but I caught it before I assembled my heads avoiding a huge problem. I forgot the specs but it is very important! ou:
i think i had an oil problem because all off the tips are badly worn,1 was broken and the others where very thin. the most of the tips are around a m/m thick now. what is the best sealer for the headbolts?? and what is the best gasket set?? Is it an improvement to drill the oil feed holes a little bigger?? wilfred
