Technical SBC lifters stuck? Bent valves. Possible cause?

Your GM manual is referring to stock lifters , not aftermarket

 

There is a range of adjustment, and you can tailor the adjustment to the use of the engine, etc. If you only have a small amount of preload, then the lifter can't "pump up" as far when you over rev the engine (or drive it without all the springs installed).

I would expect it to take a while for some of the lifters to "bleed down" after valve adjustment, with a cold engine. The operating principle of a hydraulic lifter, is that the oil will bleed off between the inner and outer parts of the lifter. The clearance is very closely controlled, so they won't bleed off too quickly. If there is indeed clearance between the two parts, and there must be since you were able to disassemble them, then they will eventually bleed down.

Too much oil pressure won't keep them from settling down, while adjusting the valves, with the engine not running

 

If you valves hit the pistons when the lifters went solid, you didn't have enough clearance to start with! Valves hit pistons when they over run the valve spring and bottom out.

 

There may have been enough clearance when operating normally, but if he got it in to valve float, that could account for the damage. Running the engine without the correct springs seems like a great way to achieve valve float.

I can see a reason to do cam break in with less spring pressure, especially on a radical cam with high spring pressure specs, but I wouldn’t drive around on an engine with only half the spring pack installed.



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I'm pretty sure that's what the OP was discussing in this thread, or am I mistaken?

 

Been fun but I'm done. LOL

 

OP #1 using the Thumper cam with Comp cam lifters

Post #18 Comp cams make several different performance lifters

 

Gotcha, I'd recalled it was a later model SBC. Memory faded after that.

 

I can go with the valve float theory, especially with a lessened valve spring pressure. Possible that one bank was adjusted differently from the other? On a 3/8-24 rocker stud, 1 whole turn is a linear .0416", half is .021".

I generally set my initial valve lash on the engine stand. No more than a 1/2 turn total unless something the cam manufacturer recommends differs. To break in a flat tappet cam, I'll go a 1/4 turn past 0 lash and adjust them later (while running) after I dump the oil and filter.

In this case, look everything over, make sure the rocker studs have not pulled out. Look at the rockers and all of the pushrods, roll them on a surface plate to see if they are bent. If you have not done it already. Replace what is suspect, do a careful valve adjustment and educate the owner a little about beating on his ride.

 

Guys, thanks for opinions. While at the shop i checked everything once again.
I'm leaning towards valves been bent during too logn break-in period. I know why this was not optimal, let's close that now .
But many lifters are not collapsing during setting valve lash. When valves are closed, lifters on base circle of the cam, there is oil passage that should allow them to collapse. And it works that way in another SBC waiting in my garage - i opened it just to check it. So i'm going to replace lifters...
@ southcross2631 - thanks, your comment confirmed my suspicions that lifters can do it.

 

https://www.enginelabs.com/engine-tech/pumping-up-is-hydraulic-lifter-pump-up-a-real-problem-today/


From the article-
Talking about lifter pump up is like debating who’s stronger, Bigfoot or the lokness monster.,

 

@ 31Vicky with a hemi - but i have a problem not when engine is running, but when shut off (even for as long as two weeks). Lifters are holding oil so no setting of preload is possible. I take away all the slack in pushrod, than try to make another turn of nut at the valve and the valve opens.

 

If you let the engine sit for a period of time after setting preload
or , better yet, turn it over a few times will the lifter bleed down ?

 

No. In fact, even compressing lifter in a vise doesn't help. Only dismantling them entirely.

 

You might try submerging a clean lifter in a can of mineral spirits or other light fluid overnight then try to compress it the next day by hand ??

 

I'll try that while waiting for new ones. And will compare that test to lifters i know that are good. Thanks for idea. Just instead of waiting i will simply assemble them submerged in oil.

 

If you can compress them far enough to get the snap ring in , they're bleeding down .....

 

Will try Thanks.

 

Ok, i've finished that engine a while ago. Bent valves were from owner not showing up a week after starting engine to mount second spring from set. I mounted engine at his place then he proceeded to do the wiring and stuff. One burnout too far and valves were bent. Let's leave this.
Lifters were pumped up when i set lifter preload. Setting it caused valve to open, and that was frightening me - i thought that valve will bend when i start the engine. In the end i said - screw this. Bend you #$%^. I started the engine with preload set with slightly open valves. Engine was difficult to start, then it coughed, and after a minute of running it had smooth idle. So problem (which never existed) solved. I'm just not so used to that hydraulic lifter thingy. Most engines i did were non-hydraulic.
Anyway - thanks for all that tried to help!

 

Thanks for coming back with the outcome ??

 

You can never give a good advice if you don't know if previous given advice was good .