Head / Valvetrain Noises and Questions

[OldsFan]

I've had an annoying tick coming from the passenger's side cylinder head.  The ticking isn't there when I first start the engine, shows up after it begins to warm up and disappears again once at operating temp.  The tick is definitely not from the bottom end (not a knock) and is in the rear of head (either #6 or #8 cylinder).  It seems to get louder on "overrun", like if you run it up to 3K RPM and the let the throttle close - but only until it reaches full operating temp.

I also have bad valve guide seals and get the nice puff of blue at start up and a fun little drip coming off of the covers on both sides.

The covers have never been pulled (I think), so I pulled the valve cover on the passenger's side and I am trying to decide what I should do at this point.  I included some pictures just for reference.

• I have never adjusted the valve train on a 305 (or 350 for that matter) SBC.  I have been reading and hear that I need to do this with the engine running, which seems like a little overkill for a stock, street driven, hydraulic lifter motor.  Is there any way to do this without the huge mess of running an open valve train?  Can I find zero lash without priming the oiling system separately (engine's been sitting for a week or so)?  Is there a snowball's chance that I can get this right having never done it before?
  
• Should I replace the valve guide seals (umbrellas)?  I've done this once before with a friend on a 350 SBO.  Is it much different?  We used the "rope trick" to do that one and I have a decent spring compressor.
  

Thanks!

[bd]

See Valve Adjustment at the bottom of page 6A4-6 (pg 525) of the 1987 Repair Manual.  Don't worry about the year of the manual; the procedure is pretty standard.  Carefully, inspect the rockers and pivot balls for wear, as well.

Regarding your choice of valve guide seals...

...You can use Felpro Viton Positive-Stop valve stem seals, which are effective and 'do not require machining' of the valve guide boss, or you can use Teflon Positive-Stop valve stem seals that 'require machining' of the valve guide boss.  For an otherwise stock configuration, the Viton seals are preferred and cost less to install.

However, I recommend you use the OEM valve stem o-ring seals in conjunction with the press-on Viton seals.  The o-rings are captive between the valve stem and the spring retainer (Items 23 in Fig. 5, pg 526), adding an extra layer of protection against leak-by.

In addition, verify the oil pressure with a manual gauge.  What viscosity oil are you using?  When was it last changed?  When a valve begins ticking the way you describe, replacement of the lifters may be the only recourse.  If you remove the lifters, be sure to inspect the cam lobes for wear.

[bobcooter]

Sounds like it may be a lifter acting up. I didn't notice how many miles on your engine. Since it comes and goes, adjusting the valves may not help. If the lash was out, I would think it would probably tick all the time.

[OldsFan]

Thanks for responding....  The link to the manual is great.

In addition, verify the oil pressure with a manual gauge.  What viscosity oil are you using?  When was it last changed?  When a valve begins ticking the way you describe, replacement of the lifters may be the only recourse.  If you remove the lifters, be sure to inspect the cam lobes for wear.

Just for reference, I got the truck about a year ago.  It has had this minor tick from day 1 of my ownership.  In the summer, it is only there for a minute or so because the engine warms so much faster (I guess).

• I checked the oil pressure with a mechanical gauge before I took the valve cover off.  It stays pretty steady at about 30 psi once warm at idle.
• Oil viscosity is 10w-30 (winter).
• Last change was about 300 miles ago.  I included some Rislone treatment with that change to see if it had any effect on the tick.  Planning on changing it again before 1000 miles just because I don't know how much I trust the Rislone.

If I were to swap the lifters, I technically need to replace the cam, though, right?  I don't want to alter the performance characteristics, so I'd need to find a "close to stock" cam as well, if that even exists...

Sounds like it may be a lifter acting up. I didn't notice how many miles on your engine. Since it comes and goes, adjusting the valves may not help. If the lash was out, I would think it would probably tick all the time.

Hi Bob - The engine is completely original.  It has under 67,000 miles on it (and the truck).   You may be right on adjusting the valve lash not fixing the problem.  I was more thinking that I would replace value guide seals and then properly set the valve lash.  If the tick remains the same afterwards, I'd know what I would be doing come spring (cam and lifter replacement). 

What if I make it worse, though?  That's what I really want to avoid.  The way it is now, it is just annoying - I don't want to overtighten and flatten the cam, for example.  Sounds like bd's link to the manual has me covered on that, though!


One more question for anyone: If I can locate the one lifter causing the tick, could I get away with just replacing that one lifter?

[bd]

You have to install new lifters when you install a new flat-tappet cam.  However, you do not have to install a new cam when installing new flat-tappet lifters. 

Yes, you can replace just one lifter, but bear in mind that all of the lifters share similar mileage and wear with the camshaft.  If only one lifter needs replacement, don't be chinsy - you'll have the engine torn down to the same extent whether replacing one or 16 lifters.  If the cam lobes appear in excellent condition, replace all the lifters as a set, using plenty of cam lube between the lifter feet and the lobes.  Then, add a pint of GM EOS to the fresh engine oil.  Replace the oil and filter after ~100 miles, adding another can of EOS.

Usually, if one or more lifters are worn even a little concave, the cam and liters should be replaced together as a set.  Think of it this way, both the lifter foot and the cam lobe are wear surfaces - if one is worn, so is the mating piece.

[OldsFan]

Ok, I think I got it.  So here's my plan:

• Since I only have the valve covers off, I am going to just replace the valve cover gaskets for now.  That'll stop the annoying leaks (I hope).
• I am going to ignore the tick until the weather gets better because it doesn't seem to be a significant problem right now.  If it changes or gets worse, I'll have to do something sooner.
• Come Spring, I have to (because of a leak) pull the radiator core and AC condenser, so that should give me space to swap the cam and lifters.  I assume I can do that with the engine still in the truck.

So that leaves two questions: 

• What kind of cam should I be looking for? I want stock performance, nothing crazy.  Any idea what the factory specs are on my 85's camshaft?
• Should I do the valve guide seals that "require machining" (need to remove heads in that case) or just do the basic ones that don't require machining...?  bd if I understood you correctly, you're saying use the no-machining required seals WITH the OEM style ones.

Thanks again!

One last thing: On valve cover gaskets with "dimples" (see the picture), do the dimples go towards the head or towards the valve cover?

[bd]

Before tearing the engine down, check the compression.

You can replace the cam with the engine in the vehicle, but you'll have to cut the vertical sheet steel support in front of the center of the radiator.  Just bend it out of the way, then resecure it with a 14-gauge steel fishplate after the cam swap.  Or, fabricate a removable section for the extra three inches of room needed to R&R the bumpstick.  Search for a cam that will boost low end torque.  With 67K on the engine plan on new valve springs to match the cam profile.  Thoroughly inspect the pushrods, rockers and valve tips while apart.  There are many threads on this Forum regarding cam selection that will benefit your search.  Plan on a double roller chain timing set, as well.

For a stock/near stock engine configuration I would use the Viton press-on seals AND the square-cut o-rings as previously stated.  Do not use the OE umbrella seals.  The Viton seals are less costly to purchase/install and more forgiving in the installation technique.  You will be pleased with their performance.

[OldsFan]

Hi Rich - Ok, I think I got it on the valve stem seals.  I was confused when I read your original post, but your previous post makes it clear.  I'll plan for the cam/lifter swap sometime this spring.  Thanks for the help! 

[OldsFan]

Hey Rich - I was getting ready to put the valve covers back on with new gaskets, etc. and I noticed something.  This is probably a dumb question, but I really want to know...

I attached an updated picture with arrows on it.  Can you tell me why the springs with orange arrows and red arrows are different?  It isn't intake versus exhaust - they'd have to be alternating.

Looks almost like the orange ones have shims on them - but I know for a fact that these heads have never been worked on.  They are stock.

Thanks again!

[bd]

Take a closer look.  The valve configuration on a SBC is Exh-Int-Int-Exh-Exh-Int-Int-Exh.  The red arrows are pointing to exhaust valves.  The endmost valves will also have those retainers.  The retainers appear different, because they're rotators.  They're designed to rotate the valves around the seats as the valves open and close to extend the service life of the exhaust valves and seats.

[OldsFan]

Wow....  I feel pretty stupid for not thinking that all the way through.

Sorry about the question, but I am really glad that you answered it.  You are 100% right and I just learned a bunch of stuff that I am not going to forget!

Thanks again! 

[bd]

Never hesitate to ask a question when something seems confusing.  And never hesitate to question a confusing answer.  You're welcome to whatever help we can provide.