5.7 Valve adjust 99 Tahoe

[inthechateau]

I finally got time over the holidays to reassemble my project Tahoe engine. At first I turned the oil pump to prime everything prior to intake install. I got good oil pressure and it bled through the push rods. Adjusting the valves turned into a fiasco. I am used to going zero lash then an additional 1/2 turn to center the lifters. But when I did this I had no compression. I backed off all lifters to zero lash and I got good compression. Is there a probem I should be looking for or is this 5.7 a zero lash and let it go? I have to pull the covers again for a couple that are still tapping (too loose). Apreciate your input.

 

[DevilDog]

I just did a top end rebuild on my 5.7 this weekend.I had the same issue. Found out that its a zero lash and stop issue, anything more and it opens the valves. After looking into it discovered that these enginges are designed to run at zero lash, sounds sloppy, but after 5 minutes of running, mine was purring like a kitten.

 

[SunlitComet]

Service manual say 1 full turn after lash is removed.

 

[DevilDog]

Absolutely right sunlit, one full turn past, as im sure all engines will be just a little different to some degree. I know that when I did mine the extra turn was enough to keep the valves stuck in the open so I had to back them off to just zero lash.

 

[retorq]

0 lash is no up and down movement of the pushrod, it should still be able to spin freely. If you cranked them down till they didn't spin then went one full after that, you did it wrong. I've always gone 1/2 turn past 0.

If the lifters have oil in them or not will determine whether one full is too much as well.

 

[DevilDog]

0 lash is no up and down movement of the pushrod, it should still be able to spin freely. If you cranked them down till they didn't spin then went one full after that, you did it wrong. I've always gone 1/2 turn past 0.

If the lifters have oil in them or not will determine whether one full is too much as well.

Sorry I wasnt to clear on what I did, I went to zero lash and then the extra turn, was absolutely to tight as I could actually see the valve opening up and had no spin on the pushrods at all, so I backed them off, in the end it looked like it would have been about a quarter to half turn past zero lash. I still had spin on the pushrods but they werent "loose".

 

[retorq]

Sounds like you got it right the second time.

 

[DevilDog]

Sounds like you got it right the second time.

Finally...something that went right these last couple of days lol

 

[inthechateau]

getting to the right side (even cylinders) is easy, only have to pry from under a couple of stand offs and lossen the dip stick tube. the left side is a pain having to unbolt the A/C power steering bracket. I have an extra set of valve covers and I'm going to modify one. Drill 1" holes over where each rocker bolt is so I can run the engine to make adjustments with out making a big mess and possibly start an oil fire. Plan is to back off till lifter starts ticking then adjust it in until it stops then call it adjusted. If this modified valve cover works I'll call it a loaner to forum members for future use.

 

[DevilDog]

Hmm, interesting concept you have there...let me know how it turns out for you. I seem to remember quite a few years back and older gentleman here in town that used to wrench on everyones cars having something similar. He took a set of high rise covers and cut a strip down the center of them and used to do all his SBC's this way. but of course cant get away with that anymore. let me know, I have some extras too might just steal the patent before you can do it lol