hey i have a very fresh (500 miles maybe) 400 with some light tapping noise right at start up every once in awhile and goes away within a second or two. sounds to me like lifter tapping. is this normal? i can't remember it doing this before the rebuild. the only things different would be a cam, intake, headers, roller rockers, and they might have added stiffer valve springs with the cam. should i be talking to the engine builder or am i just paranoid with this engine?

oh yea this is in a 77 f150 4x4 with a C6 if that matters.

 

You could have one of two problems:

One or more of your lifters does not have the preload properly set. After a rebuild it is necessary to set the preload on each lifter by shimming the lifter pedestal and checking for proper rocker geometry. If you have adjustable stud mount rockers you can re-adjust them.

One or more of your lifters has a problem and is not pumping up. An oil passage may be blocked with a piece of debris from the new engine. A cleaner will not work to remove hard particles. Sorry but it this case you will need to replace your lifters in order to fix the problem. You could pull the lifters and dissassemble each one individually (they are matched parts) but it would be cheaper and easier just to replace them all. You would have to go thru a cam break in again tho...

Either way you will need to go back to the engine builder.

 

alright, thats what i was afraid of. thanks for the help.

 

Not to sound ignorant, but I always thought that when the engine was shut off, any valves that fell in the open position would compress the associated lifter, bleeding it down. Then when the engine started back up, it would take a second or so for the oil to pump the lifter back up. What am I not understanding correctly? Thanks

 

thats what i was hoping was the deal, but the old engine never seemed to do it, so i thought that stiffer valve springs would be why this is happening. but now it seems like i have a constant tick in the engine, which leads me to go with what Eric was saying. i think this tick is caused by the lifter because of two things- 1 i have the clatter at start up- two sounds similer to a exhust leak (i do have new headers) but the bolts are all still torqued down and i can't feel any leaks and the noise doen't get louder with engine load, the tick is the same volume but equal with engine RPMs. does this sound right? any ideas? i hate this bacuase it took me almost 2 months to get this truck back in shape only to have to go back!

 

The lifter will pump back up as soon as the spring pressure is released to take up the slack in the valvetrain. They should never click unless dirt is blocking the oil passage or the preload is set wrong and the plunger is hitting the retainer.

 

What cam and lifters do you have? Have you done a compression test?

 

not sure on the cam, but the roller rockers are comp cams roller rockers. no i haven't done a compretion test yet, should i?

 

i think the cam if i remember correctly has something like 284 duration and 488 lift, sound any good?

 

If you have strong cam particularly a Comp Cams they tend to be a little noisy from the sharp ramp profiles they use. Anti pump up lifters also may add to the noise. I wouldn't normally expect noise on start up unless it had sat for a few day.

 

well i only hear it if it sits all night and through the day, when i go to start in in the evening is when it clatters, normaly they don't.

so your saying the constant tick should be normal? bacause of the cam? I am not real familir with any kind of performance engines so i don't know what to expect. thanks for the help

 

I have had a few engines with roller rockers, and they can be a little noisey. Some aren't bad, But I have a friend with a comet and his were bad enough that he took them off.

 

is there a way to ajust these roller rockers?

 

Noise means metal to metal "beating" is taking place which is deadly. A solid lifter cam is designed to take the beating and you adjust them periodically to take up the slop that has been beaten into the valve train.

An extreme ramp in a roller cam that makes noise means that your springs are not heavy enough to follow the ramp which is also a bad situation.

 

First you need to find out if the cam is a mechanical or a hydraulic. Mechanical cams are on the noisier side due to the "open" lash or adjustment you need to run them. In other words, a hydraulic cam assumes 0 lash and then 3/4 to 1 turn to bury the pushrod into the lifter for preload. This utilizes full hydraulic load and quieter operation. The mechanical cam actually needs space between the top of the valves and the "roller" when the cam is at the base circle and the spring is not compressed. This space is called mechanical lash and usually is set when the engine is cold, with a feeler gauge. Few, but some cam manufacturers require the lash to be reset after 500 miles. Wear can be most aggresive during the first 500 to 2500 miles on a normal motor rebuild. If you do indeed have a mechanical cam, and the lash was never rechecked, this may be the time to do it. Misadjustment can make for a very noisy valvetrain. If the cam is hydraulic, I would still readjust all rockers. (o lash then 3/4 turn down) I've also seen valve springs go away on these motors, but this usually nets a dead cylinder.
Heavy springs would have caused problems from the beginning. Other than readjustment of valvetrain, it could definitely be lifters. There used to be three manufacturers of lifters, but unfortunately, two have called it quits in the last two years, making the lifter market fragile indeed.
Hope it helps.