I have a 302 ('86 block, 28oz imbalance) with '65 289 heads (round pushrod
holes, rail rockers, 53.5cc chambers) it has a stockish hydraulic flat
My #8 intake valve makes a ticking/tapping noise. It sounds a lot like when
a rocker arm is too loose, except perhaps a bit of a deeper tone. With the
engine running and the valve cover off the noise is present. When I push the
rocker arm (at the valve tip) toward the front of the motor, the noise goes
away and the motor doesn't make any noise. When I let go it will stay silent
for a few seconds, then start making the nosie again. If I push the rocker
arm (at the valve tip) toward the back of the motor, it will also make the
noise. The motor does not make this noise when cold (if it does, it is very
faint), only after running for 5-10 minutes to get up to temperature.
This noise is not present when turning the motor over by hand. I checked for
clearance issues between the rails on the rocker arm and the retainer, there
are none. I checekd to ensure the rocker arm slot is long enough and is not
binding on the stud, it is not. There is no sign of abnormal wear on the
valve tip or the rocker arm. The valve spring and damper appear to be intact
and not binding. The damper does not appear to be hanging or binding on the
If anyone has any thoughts on what this may be I'd appreciate it.
My rocker arms are adjustable. Anything before '69 (or was it '72?) is adjustable. I've tried setting at the normal zero lash + 1/4 to 1/2 turn. Doesn't quiet the noise down. Obivously it clatters loudly with more than zero lash. I've tried slowly tightening it with the engine running starting at greater than zero lash all the way down to when the engine starts running rough from the intake valve not closing all the way. The noise is present the entire time.
If I push hard on the side of the valve spring and/or retainer (towards the front of the engine) the noise goes away. I don't believe it is a problem with the rocker arm, and I doubt it is a lifter or pushrod problem. I've tried swapping a rocker arm, ball pivot, and adjusting nut from a different valve and the noise persisted with the same symptoms, quieting down when pushing on the rocker arm toward the front of the engine. The other valve with the hardware that used to be on #8 intake was quiet, no abnormal noise.
Are the valve guides in good nick?
Is there clearance inside rocker to stud?
The rocker is held there by valve tip..Right ?
Check that rocker is not hitting valve keepers or retainers..
Have you changed rocker to another position ?? To see what happens?
Have you checked that rocker's contact on valve stem is in middle of stem through whole rotation...
Mark with texter and turn engine, the texter mark should be in middle of valve.. If not there is a geometry problem...
Silly question but there isn't a broken Valve spring ????
It has happened!!!
Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic!
Tuned & maintained by "Peppertree Perfmormance". Dart block, Scat 4340 steel crank, Custom C.P pistons.Oliver rods.. Mal Wood twin plate clutch.. Twin SC61/2's,482 rwkw/ 645 rwhp..
Passengers, myocardial infarction material..
Not sure about valve guides. What I know about the heads is that they have less than 25,000 miles on them (just over 18,000 of them by me on this 302) and they were rebuilt by a performance shop in PA.
Yes, they are rail rockers, centered over the valve tip by rails on each side of teh rocker. There is no interference with the retainer or locks (I did have a problem with that on 3 valves, not #8 intake, but quickly fixed that with the ol' bench grinder).
No funky geometry issues. These aen't roller rockers and my cam is pretty much stock so it's not as big a deal, but there are no signs of poor or improper geometry.
I've tried switching the rocker with another known good and also a new rocker (includes pivot ball and nut too). The spring does not appear to be broken, and from what I can see the damper looks alright.
At this point I'm thinking it is probably the valve guide (no way to check that, is there?) or the spring or damper. I suppose I could remove the spring and damper with the head on the car, so that may be worth doing next.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.