Hey guys I bean having an issue with a tapping noise,I can hear it in the morning when engine is cold then it goes away when it warms up,But yesterday I was driving at about 60 mph and as I slowed down I heard this noise, It went from a rattle to a tap as I came to a stop,I put it in park opened the hood and I could hear the noise and if I revved the engine it would turn to a rattle, so I turned it off, checked oil level it was good,I go to start it up again and the noise is gone, drove it all the way home about 2 mile at different speeds no more noise. do you guys think it may be a collapsed lifter how can I check for one, any help is appreciated thanks. All my info is on my signature.

TASBOJ.

 

I would bet money on it being a loose push rod. I could be lifter too but we have had several discussions lately about how non adjustable valve trains get after things get worn in. Only way I know to check is to turn engine over with valve covers off and when valve is closed see how much play there is. Someone else will have ideas as well......

 

Let me just start off by saying that I am guessing noting has ever been done to the heads to run on today's unleaded gas and that the original valve train is still intact.

Yetiman is on the right path as far as removing the valve cover, and I would start on one side first before removing the other side. The first thing to do is figure out which valve and how many there is making the noise. The fastest was to do this has some potential for injury and very likely to get oily. However, if you wear a pair of leather gloves and stay clear of moving parts you will be safe from harm. Safety glasses would not be a bad idea as well.

So pick a side and remove the valve cover. (With the engine off) take note if there is any sludge, or chunks on top of the heads along the exhaust manifold side. This is very common in a 40 something year old engine that has not been touched or has had to sit for any length of time.

Next take a aluminum can, (Something like what pop or beer comes in, not one your pork and beans come in.) and cut the top and bottom of, then cut down the side so you can flatten it out. Then cut it into 16 strips. Use the leather gloves for this as this will leave a nast cut if your not careful.

Starting with the first valve closest to the front, take one of your strips and insert it between the rocker arm and the valve tip. If the rocker is compressing the valve spring, rotate the engine by hand until the valve closes then 1/4 turn more. you will then be able to rock the lifter off the valve stem. I tend to place the strips in with the label side up so that the valve stem is on the unpainted side.

Once in place, hold on to the strip and have someone start the engine. rev the engine to 2000 RPS and hold for 30 seconds and shut it down. Carefully lift the rocker arm up and remove the strip. Here is how I "read the strips:

Painted side should have a slight impression matching the footprint of the rocker arm and some if not all the paint in that area rubbed off.
Unpainted side should be smooth or just the impression of the rocker arm showing threw.

If you see a round impression in the strip, or even several round impressions then this valve is causing your noise.

Use one strip for each valve so you can compare later one from another.

I am going to guess that your problems are going to be found with your exhaust valves, because unleaded gas tends to burn them out unless the heads have been rebuilt and hardened valve seats have been installed. If you have a lot of "trash" on top of the heads when you removed the valve covers, and you didn't get real oily during the run test, then you have lifters not getting enough oil to keep them pumped up.

There are many other things that could also be causing your noise, but your looking at a top end overhaul to get rid of it......

 

Thanks for responding so quickly,my engine was rebuilt last year in april nothing fancy everything is stock ,the oil pressure has always been low at about 10 psi at idle and about 40 psi when going at 70 mph,I have holley jets #70 as oil restrictors in the oil passage to valve train, motor runs good lots of power no smoke just this noise that stared resently it comes and gose, I will take valve covers off and check and I will get back to you guys with what I find thanks agian.

TASBOJ.

 

10 PSI? Sounds like the cam bearings weren't changed, or they were damaged on cam install, or the crank bearings were wiped somehow. IF this is not the case then I would run some Seafoam through it to clean out all passages. Then put in a new oil pump. And some straight 30wt oil.

 

When the rebuilting was the rocker arm shaft replaced. Or checked the underside of the shafts as this where all the wear is & the rocker bores lower 1/2 of them. If your gauge is correct then yea something not right then your only getting 10 psi with #70 restricted oil jets in the heads for oil supply to the rocker arms. You may have to much wear/slop with the rockers & shaft clearance since most the oil be stopped.

Putting in oil restrictors for the rocker , I've always thought was a lame idea and would never do it. Some of the engine have going well over 200,000 mile from the factory that did not have any mods done to the oiling system. Yea I know the #7&8 rods are known for coming out the block at high red line RPM's when taken over 6,500 to many time.

Then maybe only then the oil restrictors would do any good at lubing the rear rods & main bearing.
orich

 

2XX on that ..... 10PSI sounds way too low. I can't remember was stock oil pressure is right off hand, but I what thinking around 50 PSI at idle, and increase 10 PSI for every 1000 RPM. Your drive rod for the oil pump may be slipping and the low pressure will cause your lifters not to fill up and that would explain the lifter rattle.......

 

Most common oil at idle about 20-25 & 40-50 psi highway for the average fe was all good for a motor with 30,000 100,000+ The 460 is much higher at idle about 50 psi.
orich