noisy valve train

[big dan]

I recently installed a set of tall aluminum valve covers on my engine and while I had them off I adjusted to valves to make sure they were all still tight. now I have a nocking sound coming from the valve cover. its loud and kinda sounds like a rod knocking but its in the valve cover. I pulled the valve cover off and started the motor so I could see where the noise was coming from but it had stopped so I checked the valve cover for wear marks and there are no rubbing marks so I know my rockers arent hitting them. put the valve cover back on and the noise continued.

I have a 350 with tbi center bolt heads a comp 268H cam and stock rockers. never heard the noise till I put on the aluminum valve covers and like I said I cant find any rubbing marks. any ideas on what the noise is?

 

[sooner]

which side is it on and are you running a tbi system or just the heads.

 

[82Scottsdale]

did you tighten the rockers how they are supost to be or did u just tighten till each nut is tight, if u did the the valve it prob slapping the pistion

 

[4X4HIGH]

Aluminum valve covers will make the valve train sound alot more noisy.

 

[big dan]

you can hear it on both sides and Im just running tbi heads with a carb.

I tightened the rockers the way they are "suppose" to be tightened but everyone does it differently. I back the nut off till they rattle then tighten back up till it stops then another 1/4 turn so Im sure the valves arent hitting the piston.

4x4HIGH-That is kinda the response I was looking for and I guess I should have stated my question a little more along the lines of "would aluminum valve covers amplify valvetrain noise?" because thats really what I think it is.

thanks for all the replies

 

[sooner]

just curious on the side because i had a fuel pump that had too much slack in its arm and it kept slapping the fuel pump shaft. i couldnt tell were the sound was coming from and ended up taking both valve covers off and trying to adjust the valves with no success. it sounded just like a lifter clacking and i about gave up when i decided to check the fuel pump. held a long plastic handled screwdriver on it while running and could tell immidiately what the problem was.

i also have tall alumimum valve covers but have not noticed any difference in sound from the steel ones. may just be me

good luck

 

[big dan]

good idea on the fuel pump, Ill go ahead and check it out tonight when I get off work. sounds like its coming from both sides but it doesnt hurt to check. thanks.

 

[4X4HIGH]

You're better to do the adjustment with "zero lash then 1/2 a turn more" rather than only 1/4 turn.

 

[sooner]

i couldnt tell which side mine was coming from and when i took the valve covers off it seemed to go away, just because all the valve noise with the covers off would drown it out.

 

[mnstrburbon]

igf it got louder with when you changed the covers then there is youre answer throw the old ones back on if its quiter, then either they are hitting or the aluminum idea never herd or noticed it before.
check and see if it is hitting the filler opening or pcv valve maybe its in a spot where they are made to go right or left, i have had a set hit the bolt bends or slots check there for rub marks.

 

[big dan]

ok the rattling in my valve train is getting worse. its knocking hard on start up and Ive been afraid to drive it. if checked it while running without the valve covers and you can distinctly hear it with the valve covers off now.

one thing I did notice is that it doesnt seem to be getting much oil to the valve train. Ive seen motors shoot oil over the fenders without the valve covers on but on mine the oil either slowly runs out the pushrod hole or none comes out at all. and my motor doesnt seem to have very high oil pressure. it used to run 40 lbs or more but now when it gets warm it falls down to about 15-20 at an idle and stays around 35 at highway speeds so Im kinda scared that my motor is about to fly apart.

4x4HIGH- just noticed your post about 0 lash then half a turn, could only turning it a 1/4 after zero lash keep the lifters from pumping enough oil to the valves or am I way off with that thinking?

two things that I have been told is bad lifters not pumping up or the oil pump is weak. does this sound like a logical explanation?

sorry for all the questions but I've never been good with diagnosing engine related problems and Im starting to get worried that Ill be spending my money on a new motor soon and thanks for all the help.

 

[4X4HIGH]

Only going zero lash then 1/4 turn could still make valve train noise. I just had my covers off on the new engine i built and i have very little oil spray at idle but off idle it starts to throw oil pretty good. Nothing to worry about there unless of course you're not getting decent oil at a higher RPM. How many miles are on your engine? Oil pressure is controlled by a couple of things, the fit between the crank and rod/main bearings and also between cam and cam bearings, and also the oil pump pressure relief valve spring. If you have a combo of low tension on the pressure relief spring or a loose fit between the bearings then you'll have low oil pressure.

 

[big dan]

Im not sure how many miles are on the engine. I bought the truck from jackedjimmy350 on here and he said that the motor was suppose to be a low mile rebuild but he didnt know that much about it either cause he bought it with the motor in it so there is really no telling but it has good compression and doesnt use or leak any oil. as far as the condition of the bearings I have no idea about.

Ill try adjusting the valves again the way you suggested and see if that helps. do you think it would be worthwhile to try a new oil pump? I can get a pump, pickup, shaft and the plastic clip for around $25 and its due for an oil change anyway.

 

[4X4HIGH]

It is highly unlikely that the oil pump is your low oil pressure problem. It is however more likely of the fit between the crank and rod/main bearings as the culprit and just changing bearings isn't going to help either since there is wear on the crank. The crank would need to come out and be machined to the next undersize and then new bearings installed to solve your low oil pressure problem. Before i did any of that though i would suggest installing a good quality mechanical gauge for testing purposes first to verify that the gauge in the truck is accurate.

 

[big dan]

thats not really what I wanted to hear but I guess Ill have to bite the bullet and fix it.

tomorrow Ill pick up a new gauge and adjust my rockers that way you mentioned and see if that helps if not then I guess its time to tear it down and fix it.

thanks a bunch for your advice and sharing of knowledge. I may have many more questions when it comes time to put a crank back in.