I tightened my rocker arms down 1 turn past zero lash awhile back. After a week or so it started to sound like I had a bad exhaust leak.
I tightened them again last weekend, they were all loose except 1 and 1 of them had completely jumped off the push rod. Another one was loose enough that it was beating up the top of my valve cover.
Well, they're loose again and the car is running like crap.

What can I do to keep them down??

 

Use jamb nuts, or get new pinch type rocker nuts (summit, jegs, etc). Sounds like the current ones no longer hold the stud tight enough.

The jamb nuts are thin nuts that you tighten against the rocker nut to keep it in place. Theyre hard to tighten due to the lack of space, but they do work. The thread size you want is 3/8-24.

 

Where can I get stuff like this from?

 

Refer to post #2.

 

Can I get them from a local parts store is what I meant

 

You can get the jam nuts from a hardware store. the one i work at has them. also you might want to consider...

Do the heads you are using have pushrod guide plates? Do the heads youre using have slotted pushrod holes or round? Do you have self aligning rockerarms.

 

As far as I know it's all stock, it's a 350 that's been swapped in but the arms and pushrods are stock. The heads are 434 castings from a 305. I've been having problems with it overheating, if I put a thermostat in it it always overheats no matter what I do.
At about 210 the rockers start chattering.

 

just throwing this idea out there..... but are you sure the nuts are loosening?

Make sure that the studs arent pulling or the cam isnt going flat. Either of those can cause the same symptoms.

 

I believe something else is going on here. Devil's in the Details.

Are the nuts actually moving? That is, moving up (backing off) the studs?

Are you running stock rocker arms?

How are you going about re-tightening the nuts once they've become loose?

When you adjust (tighten) them, you should be able to see a certain number of stud threads showing above the nuts. Now, when they become loose are there fewer threads showing?

I'm trying to figure out what's going on here.

BTW, auto parts stores sell new adjusting nuts. They, like stockers, are slightly oblong at the top of one end and it's that "oblongness" that keeps the nut from backing off. If the nuts have been tightened/loosened/re-tightened several times, that feature gets rounded off, so the nut can no longer reliably remain in place. Oblong works - round doesn't.

Jake

 

Guess they were still tight all along, I was just 3 quarts low on oil I just filled that last week and I don't see any on the ground and the car doesn't smoke.

 

Being low on oil wouldnt affect your rocker arms at all. Unless your ground the lobes off your cam. Inadequate oil on the camshaft would allow friction between the lifter and cam lobe, causing the lobes to grind down, and destroying the lifters. Id pull the intake and pull a few lifters and check the bottom of them. I just had to replace my camshaft from a lifter failing and grinding off a lobe.

 

Staying out of this discussion but congratulations to Jake Jr and his son. Awesome!

 

Agreed to check rocker operation--
After adjusting rockers, pull the power feed from distributor
and have someone crank the motor.
Watch rockers for lift-- flat // worn lobes or bad lifters will
be evident.

 

Thanks, *doc. I'll pass it along to Ryan, too.

Jake

 

It is possible that it may be the lash is improperly adjusted. The lifters must be full of oil and on the base circle of the camshaft for proper adjustment. To do this, start at one end of one of the cylinder banks. Turn the engine by hand until you see the rocker arm that you are adjusting rise all the way up(valve all the way closed). Then with the rocker arm loose, either move the pushrod up and down or spin it between your fingers while snugging the rocker arm nut down until you either just start to feel resistance(spinning the pushrod) or the pushrod just starts to not move up or down anymore. Then give the nut between a 1/2 to 3/4 turn and move onto the next one repeating the whole procedure on that valve. Its easier to start at the end of one bank and move down the line so you know what has been adjusted and what hasnt. I do this on my valves and have no issues at all or need any readjustments. I prefer the spinning the pushrod method as I can get a more accurate feel of where the lash is actually set.

 

They weren't loose this time, it was just really low on oil which was causi g some chattering. I took my thermostat out so hopefully that will help with my cooling issues. It's good and driveable now.
The cam had one slightly worn lobe when I put it in, and the cam before that was completely wiped, along with 3 wiped lifters. It's a really old stock 350 cam and all the lifters are going as they should.

 

i have a 1988 c 1500, i replaced a head, tightened the rocker arms. it ran great until i started it the next day. it had no power. what could be wrong.

 

rjd3165:

Welcome to TGO. You'll get better response by starting your own thread instead of hijacking this one - the few folks reading this thread are looking for info on rocker arms and why they loosen up on their own, where as you want more exposure by posting your own thread so more than just tyhose few folks see it.

And give us more detail, much much more detail. We need to know car year, induction system being used, what tranny, and exactly what you swapped and what you left as stock.

We're glad to try and help! But get your own thread out there on the top of the list so it's seen more!

 

i have a 1988 chevy c1500. i swapped the driver side head due to the stud coming up. its automatic and fuel injection bowl

 

i had a stud come up on my 1988 c1500 on the head that i changed. what could be happening?

 

pressed in studs can do that and will make that loose sound, bend pushrods all kinds of fun stuff. Shouldnt do it with a stock cam but once you go up in size to a point you should be using screw in studs which means youll have to get them tapped

Take the rockers off and examine what you have carefully go from there.

 

i believe that water got into my oil from changing the head that it got into the piston chamber causing it to hydrolic which pushed it out.

 

the gas in my tank was red but wasnt diesel. it would sit and run good but when i drove it, it didnt have power and would quit running. what could that be. i cleaned the tank. the gas looked like blood.