valves loosening

[baxsom]

for some reason one of the valves on my 72 BB wont stay adjusted.

it is just barely tapping so i remove the cover, start it up, tighten until quiet then 1/2 more turn.

i drive it and in a day or so it is loose again.

new nut maybe? the oem rockers were pretty worn so they were replaced with new rockers and that little ball like thing inside of the rocker but the nuts were not replaced.

just to throw it out there a lockwasher between the nut and the "fulcrum ball" would be a bad idea right?

thanks

 

[motorman]

for some reason one of the valves on my 72 BB wont stay adjusted.

it is just barely tapping so i remove the cover, start it up, tighten until quiet then 1/2 more turn.

i drive it and in a day or so it is loose again.

new nut maybe? the oem rockers were pretty worn so they were replaced with new rockers and that little ball like thing inside of the rocker but the nuts were not replaced.

just to throw it out there a lockwasher between the nut and the "fulcrum ball" would be a bad idea right?

thanks

get new GM lock nuts before you ruin the threads on the studs

 

[baxsom]

new locknuts are 3 bucks at the local napa.

hopefully i can get away with the same stud

 

[Hib Halverson]

The camshaft may be failing. As that lobe wears, clearance develops and the valve makes noise.

You should check the lobe lift by putting a dial indicator on the pushrod end of the rocker then compare your reading with the number in the factory service manual.

 

[baxsom]

but would that cause the nut to constantly need adjusting

 

[JohnZ]

but would that cause the nut to constantly need adjusting

Yes, it would - if the cam lobe and/or the lifter foot is wearing, the clearance will continuously increase. Try new GM nuts first (no lockwashers - the nuts are special prevailing-torque lock nuts).

 

[baxsom]

thats a good point because in that case the nut would not be moving but the bottom would be dropping out of the lifter making the play come from the bottom. sooooooo. i adjusted the valve again using a new locknut from napa (extremely reasonably priced btw) and then counted the threads on the stud. if it loosens again i will be able to see if the nut came up or if the lifter went down.

 

[Art Jett]

I am in the process of replacing the cam, lifters, pushrods, rockers, rings, oil pump, timing set, valve covers and all bearings because of that. I lost # 8 intake lobe on the cam and the same lifter. Started with a small ticking only at startup and got louder over about a 500 mile trip. Ended up I rolled the engine over by hand with the valve cover off and that rocker arm never moved. Not the desired effect!!! Went full roller this time.

 

[Brooklinite]

I am in the process of replacing the cam, lifters, pushrods, rockers, rings, oil pump, timing set, valve covers and all bearings because of that. I lost # 8 intake lobe on the cam and the same lifter. Started with a small ticking only at startup and got louder over about a 500 mile trip. Ended up I rolled the engine over by hand with the valve cover off and that rocker arm never moved. Not the desired effect!!! Went full roller this time.

I hate to say it but that's how it happened with mine too. First a tick-tick-tick then a clack-clack-clack. One rocker was loose (#3 exhaust) so we adjusted it but the tick wouldn't go away. I tried adjusting it with the engine running but immediately noticed that rocker wasn't moving nearly as much as the rest.

I went with a roller too.

 

[baxsom]

i havent followed up yet because i havent driven the car a lot since i got the rocker nut but just idling in the garage the rocker arm is traveling equal to the others. i dont have a dial indicator to get 100% precise measurement but simply a ruler beside the rocker arm they are all moving the same amount.

i am just waiting on a good warm day so i can get it out for a while.

 

[baxsom]

update
300 miles later and the valves are still quiet.
thanks napa, at 2 bucks that has to be the cheapest fix on this car so far.

 

[baxsom]

spoke too soon but did find problem

well it looks like my above post was rather premature. i took the car out today and it started clacking again. i got it home and pulled the valve cover and low and behold the same rocker was loose again. i got to looking very closely and noticed that this pushrod was messed up.

i have both pushrod ends from that cylinder pictured here. see if you can tell which rocker arm was always going loose.

but here is the big million dollar question. do i blame it soley on a pushrod failing or is my cam toast as well. the other end of the pushrod that goes into the lifter looks fine for what its worth.

it almost looks like the ball end got pushed into the pushrod which would explain why it constantly needed to be tightened.

so be honest am i screwed. is there a XE268H in my near future

 

[Hib Halverson]

Looks to me like you have two different types of pushrods in the engine.

 

[baxsom]

Looks to me like you have two different types of pushrods in the engine.

nope

they are all the ball on end type from comp cams that came with the roller tip rocker kit.

i did think that too at first so i pulled every other rocker arm off and that was the only one that looked like that. since it was the only one that kept loosening up i think i am going to go back to the original rods, guide plates, and rockers and hope for the best. the car ran too smoothly IMO to have a wiped lobe so heres hoping for the best.

 

[Dad2]

worn ajust nut

when the threads get worn, try a new adjust nut, or will have to replace stud in head

for some reason one of the valves on my 72 BB wont stay adjusted.

it is just barely tapping so i remove the cover, start it up, tighten until quiet then 1/2 more turn.

i drive it and in a day or so it is loose again.

new nut maybe? the oem rockers were pretty worn so they were replaced with new rockers and that little ball like thing inside of the rocker but the nuts were not replaced.

just to throw it out there a lockwasher between the nut and the "fulcrum ball" would be a bad idea right?

thanks

 

[Brooklinite]

nope

they are all the ball on end type from comp cams that came with the roller tip rocker kit.

i did think that too at first so i pulled every other rocker arm off and that was the only one that looked like that. since it was the only one that kept loosening up i think i am going to go back to the original rods, guide plates, and rockers and hope for the best. the car ran too smoothly IMO to have a wiped lobe so heres hoping for the best.

Maybe you have 15 of one type and one oddball that was replaced due to a previous failure.

 

[baxsom]

Maybe you have 15 of one type and one oddball that was replaced due to a previous failure.

nope, i myself installed these pushrods about 6 months or so ago.

when i got the car the previous owner had a set of roller tip rockers that he never got around to putting on that he gave me. i decided what the hell and installed them. they came with 16 brand new 3/8 inch ball type pushrods.

of course after this i am going to put the oem rockers and pushrods back in just to see if everything is ok.

 

[Vette79]

If the pushrods are the same maybe the nut was to tight? Are the pushrods the correct length? A one piece pushrod would of be great for this application. Is the rocker stud is still good?

 

[Brooklinite]

nope, i myself installed these pushrods about 6 months or so ago.

when i got the car the previous owner had a set of roller tip rockers that he never got around to putting on that he gave me. i decided what the hell and installed them. they came with 16 brand new 3/8 inch ball type pushrods.

of course after this i am going to put the oem rockers and pushrods back in just to see if everything is ok.

Wow. I can't believe that pushrod ever looked like the others.

Good luck with this.

 

[baxsom]

If the pushrods are the same maybe the nut was to tight? Are the pushrods the correct length? A one piece pushrod would of be great for this application. Is the rocker stud is still good?

the stud still looks good. the pushrods are like 9.25 inches which is what from what i have read is oem length for big blocks.

i adjusted them using this method
#1 to TDC then adjust
intake
12567
Exhaust
1348

then one revolution on the crank
intake
3468
exhaust
2567

on each rod i moved it vertically while tightening the nut. then gave it 1/4 turn once it stoppeed moving vertically.
then i cranked the car and let it warm up.
then while running i did the loosen until chattering then tighten until quiet then 1/2 turn more.

i dont think it was too tight going through all that. hopefully the new oem pushrods i got last night will work without a cam change.