350 Lifers & Valve Lash oh My!

[Biggyniner]

Hello gentleman,

So I have installed a new head and now it is time to install the rockers. When I have built an engine in the past, I use the hotrod magazine / dry lifter method. That is, do not soak them and pump them manually. Instead you coat them with assembly lube and drop them in. Then tighten each rocker until there is no more play on the pushrods. Next, you rotate the engine 90 degrees and repeat that tightening process. Do this 8 times total. Finally you tighten each one 3/4 a turn and boom your done. (kind of then you actually pour break in oil over the valley and lifters - then prime the oil pump manually until no air, only oil, is coming out of your pushrod holes)

Now my question is on an engine that has ran, do the lifters un-prime after time?

I will check when I can get back to my project, as the engine has been sitting for sometime, but if anyone knows off hand that will help me stop obsessing over this in my mind. If so I should be able to do the same process as above, but obviously on only one head instead of both.

Thanks

 

[alldodge]

Never heard anyone do it that way, but I wouldn't do it that way.

Don't know anything about your motor (no year or serial number), but I rotate to TDC on each cylinder, obtain zero lash, then tighten 1 full turn

 

[wellcraft-classic210]

I used that method some time ago on a few SBC engines in cars ( like 30 years ago ) and it worked quite well -- Less messy that a running engine by far.

My understanding is;

Yes they should collapse under valve spring load-- with no oil in them -- I am thinking the 3/4 turn your referring to is to loosen 3/4 turn from full collapse.

When the oil is fed to them they will fill and absorb that slack. And as the cam wears over time and use they will absorb more slack -- which is what the design was intended for,


The experts may have more to add -- Seems to be a lot of methods used for this --

This may be old news -- But being sure the valves are not overtightened to the point the hit the pistons etc. is pretty important.

 

[Biggyniner]

Never heard anyone do it that way, but I wouldn't do it that way.

Don't know anything about your motor (no year or serial number), but I rotate to TDC on each cylinder, obtain zero lash, then tighten 1 full turn

Do you do that with the lifters primed or not?

If you are curious here is a video of a engine builder illustrating the method I explained:
https://www.youtube.com/watch?v=5EGlb_VpTAw&t=

Your way seems feasible too. I'm just trying to do this the easiest way. I suppose with your way I can finish the intake manifold, drop my distributor back in and start rotating the engine to find TDC on each cylinder... That way I do not have to set my distributor up again and I can use the marks I made when I took it apart...

 

[alldodge]

My way is how its written in the Merc service manual. If your over all finish is with 3/4 turn more, then you don't have enough for the lifter.

The 3.0L uses 3/4, but the SBC is 1 turn

If I'm installing new lifters, then I dip in oil or use pre lube and slide them in, no soaking.

The VID
He is doing bottom all them out and then bring it up 3/4 turn. It sounds like it will work, but I'm not going to do it when its my motor. So far as how many turns, it doesn't take that many. Book says use TDC, but all I do is watch for any valve to start to open, then adjust the other one. No worry with keeping track because I use a white grease pencil and mark rocker studs as I go.

The only way it gets messy is if your adjusting while its running

 

[Biggyniner]

My way is how its written in the Merc service manual. If your over all finish is with 3/4 turn more, then you don't have enough for the lifter.

The 3.0L uses 3/4, but the SBC is 1 turn

If I'm installing new lifters, then I dip in oil or use pre lube and slide them in, no soaking.

The VID
He is doing bottom all them out and then bring it up 3/4 turn. It sounds like it will work, but I'm not going to do it when its my motor. So far as how many turns, it doesn't take that many. Book says use TDC, but all I do is watch for any valve to start to open, then adjust the other one. No worry with keeping track because I use a white grease pencil and mark rocker studs as I go.

The only way it gets messy is if your adjusting while its running

Good information, I will take your approach for this new head. Makes sense that when the valve starts to open the other is shut. So since this is a 350 small block Chevy (93). I should get it to zero lash using your method, then go 1 more turn, and that is it?

Also I am reusing the lifters, as it only has about 2 hours on it, is that an issue?

Thanks!

 

[alldodge]

Agree, but note zero lash is different then the way in the VID

To get zero lash, use your fingers and rotate the rod just enough to know its loose and will move. Your also moving the push rod up and down. Once there is no up and down movement, this is zero lash. You should still be able to turn the rod, just no up and down

 

[Biggyniner]

Understood

 

[JustJason]

Get back in there and peen the cracks then re-epoxy it and it will go for years. Just keep an eye on it and make sure your bilge pump works. Your owners manual tells you to check the oil every day and nobody does that!