Vortec Valve Lash Adjustment Nesscessary on New Long Block?

[carrera205]

I purchased a ATK Vortec long block a while back and while looking through the instal manual it says to do a valve lash adjustment after the running the engine. I was under the impression that if the lifters are hydraulic lifters then doing a second adjustment isn't necessary considering this would've been done during assembly. Anyone have some clarify on this issue?

It's a ATK VMH4 basically a 5.7 with vortec heads covering the years 96 to 00. Can't seem to find info from ATK's site on if the lifters are hydraulic but i would assume they are since that's pretty standard right?

 

[GA_Boater]

Most likely the lifters are hydraulic. But how long has a newly rebuilt motor been sitting on the shelf before you bought it?

Do the valve adjustment.

 

[achris]

Unless the rockers screw all the way down to the head (like the later V6s), then checking/readjusting valve lash is part of the 'first start up' procedure..... The spec is one turn down from zero lash. Find zero lash by moving the pushrod up and down. Attempting to find zero lash by twisting the rod is incorrect. Or do it with the engine running. Loosen the rocker nut until the valve 'clatters', then tighten until the clatter just stops. This is 'zero lash'. Then turn 1/4 at a time, allowing about 15 seconds between 1/4 turns, until you have one turn down. Repeat 16 times.

Chris.......

 

[alldodge]

Didn't notice but there is another thread
https://forums.iboats.com/forum/eng...62439-vortec-long-block-valve-lash-adjustment

 

[achris]

Didn't notice but there is another thread
https://forums.iboats.com/forum/eng...62439-vortec-long-block-valve-lash-adjustment

Thanks AD, it's closed...

 

[carrera205]

achris sorry for the cross post couldn't figure out how to delete the first one!

Ended up doing the valve lash pre-load sequence today and found that the lifters were not even close to adjusted in fact sloppy would have been a generous classification. Once I get the engine fired up I'll do a second adjustment after a bit but at least this will be good start.

 

[achris]

achris sorry for the cross post couldn't figure out how to delete the first one!....

carrera205 You can't delete a thread. If you do open one in the wrong place, rather than start another, just 'flag' it and ask a mod to move it. We're pretty quick with responding to 'flags', and it helps keep things tidy.

Chris........

 

[muc]

Attempting to find zero lash by twisting the rod is incorrect.

I’ve never heard this before. Spinning the push rod to find zero lash is what is recommended by MerCruiser and Volvo. I’m wondering where you found this information?

 

[Scott Danforth]

way too easy on an SBC to get the valves too tight by the twist method. depending on what lifters are there and what assembly lube, you can actually compress the spring in the lifter and start opening up the valve before you can stop the push-rod from spinning

once vertical slop is removed, 3/4 turn of nut (and lock down the polylock on roller rockers)

at least that is the method that was taught to me over 45 years ago

for an SBC

with cylinder #1 at TDC - adjust Exhaust on 1, 3, 4, 8 and Intake on 1, 2, 5, 7

with cylinder #6 at TDC - adjust Exhaust on 2, 5, 6, 7 and intake on 3, 4, 6, and 8

 

[alldodge]

I’ve never heard this before. Spinning the push rod to find zero lash is what is recommended by MerCruiser and Volvo. I’m wondering where you found this information?

Its in every manual (SBC V6 and V8)I have, rotate to ensure its free and centered, but the up/down is what to feel for

 

[muc]

Its in every manual (SBC V6 and V8)I have, rotate to ensure its free and centered, but the up/down is what to feel for

Yes I understand what is in the manual. But also almost every marine manual will start with something like this.



This manual has been written and published by the Service Department of Mercury Marine to aid our dealers’ mechanics and company service personnel when servicing the products described herein. We reserve the right to make changes to this
manual without prior notification.
It is assumed that these personnel are familiar with marine product servicing procedures. Furthermore, it is assumed that they have been trained in the recommended service procedures of Mercury Marine power products, including the use of mechanics’ common hand tools and the special Mercury Marine or recommended tools from other suppliers.
We could not possibly know of and advise the marine trade of all conceivable procedures and of the possible hazards or results of each method. Therefore, anyone who uses a service procedure or tool that is not recommended by the manufacturer, first must completely satisfy himself that neither his nor the product's safety will be endangered.
All information, illustrations, and specifications contained in this manual are based on the latest product information available at the time of publication. As required, revisions to this manual will be sent to all dealers contracted by us to sell or service these products.
Refer to dealer service bulletins; operation, maintenance, and warranty manuals; and installation manuals for other pertinent
information concerning the products described in this manual.


There are many things they teach us at the factory schools that are not included in the manual.

 

[muc]

way too easy on an SBC to get the valves too tight by the twist method. depending on what lifters are there and what assembly lube, you can actually compress the spring in the lifter and start opening up the valve before you can stop the push-rod from spinning

once vertical slop is removed, 3/4 turn of nut (and lock down the polylock on roller rockers)

at least that is the method that was taught to me over 45 years ago

for an SBC

with cylinder #1 at TDC - adjust Exhaust on 1, 3, 4, 8 and Intake on 1, 2, 5, 7

with cylinder #6 at TDC - adjust Exhaust on 2, 5, 6, 7 and intake on 3, 4, 6, and 8

I’ll be the first to admit that I’m no expert on hydraulic lifter valve adjustment. I’ve probably only done it 40 times. Solid lifter or overhead cam, that I’ve done hundreds of times.
The reason I asked achris about this is because I’ve never read anything by a recognized expert (like a cam or lifter manufacturer) that specifically recommended against this method.
Compressing the spring in the lifter is what you’re doing when you turn it down ¾ or one turn.
Not sure how somebody could actually get the valve to start opening and still be able to spin the pushrod (they must have much stronger fingers and much slipperier lube than I do) but I suppose anything’s possible if you try hard enough.
¾ turn is recommended by MerCruiser on their performance engines, stock engines get one turn.
The adjustment procedure that you post is what MerCruiser recommends, but most cam manufacturers want you do each valve separately so you can be sure to get the lifter on the heel of the lobe.

 

[alldodge]

The hydraulic lifter "can" move down a tad before hydraulic pressure builds enough to stop the rotation. If the lifter has next to no oil in it, then it will move down more before pressure builds enough and stops the rotation.

 

[Scott Danforth]

hey, muc, just google SBC valve adjustment. plenty of info out there. most written by the hi-per guys 60+ years ago as well as many factory race guys. the procedure has been the same since 1955 with the 267

generally anywhere between 1/2 turn and 1 turn will suffice. hence the 3/4 turn

 

[muc]

hey, muc, just google SBC valve adjustment. plenty of info out there. most written by the hi-per guys 60+ years ago as well as many factory race guys. the procedure has been the same since 1955 with the 267

generally anywhere between 1/2 turn and 1 turn will suffice. hence the 3/4 turn

Yes, I agree that anywhere between 1/2 and 1 will work fine, that’s the beauty of hydraulic lifters.
I think the reasoning behind the 1 turn on stock motors is, the amount of HP lost is very small and as the engine wears the little bit of extra preload keeps you from having to do another valve adjustment.

 

[muc]

The hydraulic lifter "can" move down a tad before hydraulic pressure builds enough to stop the rotation. If the lifter has next to no oil in it, then it will move down more before pressure builds enough and stops the rotation.

I don’t think it’s the hydraulic pressure that causes the drag that your feeling for when you spin the pushrod, it’s the spring in the lifter. If the lifter doesn’t have any oil in it just means it’s a bad lifter or the builder didn’t bleed the air out of them before installing or they didn’t prelube the engine long enough before doing the adjustment.


But I’m just looking for a really good reason to change how I’ve been doing it for 40 years.
I’m more then happy to change if a expert can tell me why.
I was very surprised to find out I had been using the jam nut on inboard props wrong for over 20 years, but I now put the big nut on last because better research came out.

I understand that there is always more than one way to get the job done. But I do like to see proof on why one way is wrong.

 

[alldodge]

Well I recon from never heard of it, and no Merc manual has it, to now 1/2 to 1 turn is a gain in the right direction. Good to know that no one knows everything, found my self on the wrong side many times.

 

[achris]

I’ve never heard this before. Spinning the push rod to find zero lash is what is recommended by MerCruiser and Volvo. I’m wondering where you found this information?

The Merc manual specifies using the 'lift up and down' method .. and I've found plenty of engines that people have used the twisting method and got them way too tight ...

Chris...

 

[achris]

muc



Service manual #31 (GM small block V8 2001-) section 3A, page 29.

Also,

Service manual #24 (Small block V8 1998-2001), section 3A, page 34, paragraph 3,
Service manual #17 (V8 1993-1997), section 3A, page 28, paragraph 4,
Service manual #15 (V8 1989-1992), section 3A, page 19, paragraph 4,
Service manual #9 (V8 1985-1988), section 3A, page 20, paragraph 4,
Service manual #3 (All Engines 1978-1984), section 6C, page 42, paragraph 4,
Service manual #2 (All engines and drives 1974-1977), section 5C, page 4, paragraph 1c.

So yes, I can see how this has never been the procedure in any Merc manual. I dare say if I went through the Volvo manuals I'd find the same.... :facepalm:

Chris.........

EDIT: Out of sheer bloody mindedness I did open a Volvo manual, first one I opened, 7748089, 5.0-5.7 V8. And right there on page 59.....

• Turn the valve rocker arm nut clockwise until all the valve
lash is removed (zero valve lash). Zero valve lash can be felt
by moving the pushrod up and down between you thumb and
forefinger until there is no more up and down movement of
the pushrod.

 

[muc]

The Merc manual specifies using the 'lift up and down' method .. and I've found plenty of engines that people have used the twisting method and got them way too tight ...

Chris...

Yes, I’ve read the manuals. But I also have attended many Volvo and MerCruiser classes and spinning the pushrod is their recommendation. As I posted before they cover a lot of things that aren’t in the manual. I don’t think up and down is wrong, but I do think spinning is more precise.

I wonder if if this is a regional thing. I know that when I talk with some mechanics in the southern US, I have to remember that when they say “won’t crank” they’re saying what I call “won’t fire”.

As far as manuals. None of the bravo3 manuals talk about indexing the prop shaft to the forward gear. But they tell us in school that it’s critical.

Oh well, different strokes for different folks. Thanks for your explanation.