First off I have a 1984 Camaro, Edelbrock Carb, no computer, 77' 350cc.

I've been hearing a brush kind of tap for about a year now. I thought it was the exhaust manifold. So I replaced the gaskets, but didn't help. Two months ago I removed the valve cover & tightened the rockers. I noticed that if I tightened one of the rockers, the tap would go away then return 3 seconds later. My neighbor told me that it's probably bad lifters, so we adjusted the rockers & put the valve cover back on. Latley the tapping has been getting louder, & is becoming more of a knocking sound.

Could this be worn lifters or is it much worse?

Or could it be the timing?


Thanks, Joe

 

It sounds like sticky lifter's Joe.

First... does it tap while idling, or only with a load? Does the tap/knock sound metallic (spark knock), or just a 'tick' in perfect rhythm?

Before you remove the intake manifold, buy some thread lock (not sealant), and apply it on the rocker arm studs. Re-set the valves so that the tapping goes away..... then shut the engine off, and wait awhile to allow the thread lock to cure.

If the tapping comes back, then you definitely have a sticky lifter(s)....

Also.... if it's only under a load, then retard the timing (turn the distributor clockwise) a drop. Keep doing this until the knocking goes away, but this is only if it's indeed the timing (but it sounds like a lifter). A really bad lifter can make the engine 'pop' when you lean into it, even at idle....

(Remember.... if the valves are set too tight, she'll run rough. When you re-set the valves, with the engine running, tighten the rocker arms down until the tapping goes away.... then turn an additional 1/2 a turn for each and every stud. Don't forget to apply thread lock, and wait for it to cure)....

 

not to take away from your question, but, i also have a ticking noise. it only happens when the engine is cold. after running for 3 minutes it slowly goes away. its a brand new gm 350 ho crate engine. im using 5w-40 mobil 1 synthetic. thanks

 

It's gotta be the lifters. When we tightened the stud down, no matter how much we tightened it the tapping would go away, then come back a few seconds later. I can still hear it at idle & it's at rhythm with the RPMs.

How extensive is a lifters/cam replacement?

What parts should I get for the repair? I know I need a Cam, Lifters, timing chain. But is there anything else?

I'm trying to sell the car & since I'm only looking at getting $1800 at the most, is it worth stepping into this project?

 

thats probly the infamous piston slap that the GM crate motors have when cold.... its "normal" for them and doesnt hurt the engine any.... more of a annoyance to you though.

 

You don't need a new cam, unless she's been running with little to no oil on a constant basis throught it's life....

Take off the manifold, remove the rocker arms, pushrods and lifters. When installing new lifters, give them a generous coating of fresh oil.... then tighten down the rocker arms in sequence of the firing order (1-8-4-3-6-5-7-2).... start with the #1 cylinder at top dead center (this way you know for sure that the valves are both closed). Tighten them down so that there's little to no 'tap' between where the arm meets the pushrod (do not over-tighten). Once done, turn the engine manually.... then repeat with the #8 cylinder, and so on.

Once done, start the car with the valve covers off.... and adjust them by ear. If you have to back off on them to get a tap.... do so, because the idea is to tighten each one until the tap goes away, then tighten an additional 1/2 a turn (nothing more, or else they'll be too tight)....

 

additionally, put each lifter under some oil and press it in... this will let the air out and fill it with oil....

with flat tappet lifters, i do this with a clean coffee can filled with oil...

 

can u go more into depth just so i know for future use? is it just because when the pistons are cold they are smaller and leave more clearance than normal? it hast cast pistons

 

Would a 77' 350 have hydraulic lifters or roller lifters?

 

yes. it had somthing to do with the piston clearance when you did a cold startup... honestly its been awhile since i read exactly why... rather then try to remember and have it be wrong, id rather tell you its a clearance thing and if you need more info, do a search online.. sorry i dont know more info off the top of my head.. *shrug*

regular hydraulic lifters..

 

Ok, I know it's been a while but I should get this project done this week. Although, I have another question.

When I remove the rockers, will I need a valve spring compressor to get the rockers back on?

Will I need any special tools to get this project done?

 

nope on the valve spring compressor....

if you;re just doing a cam/lifter swap, no special tools....

if you are replacing the front timing chain, you need a puller to get the crank gear off and a press tool to put it back on... both should be avail for FREE rental from autozone...

 

Joe, if you're just replacing the lifters, then no... you don't need a valve compressor. But if you plan on replacing the valves as well, they yeah... you definitely need one.

There are some awesome products out there, and if you plan on swapping out the cam.... definitely look into that two piece timing chain cover (for future mods), which makes dropping the oil pan a thing of the past (since you only have to remove the top half of the timing chain cover)....

Don't know how far you're going with this, but just so you know, if you plan on replacing the valve springs, you don't need to remove the heads.... just get an air compressor and plug it into the spark plug thread for every two combustion chambers you're working on.

Good Luck, and don't get discouraged.