adjusting engine valves

[michael evans]

I took the T for a drive Saturday and made a couple 1/8 mile hits then it sounded like it spun a rod bearing.

The oil pressure looked good and the sound was coming from under the left valve cover (the easy one to remove), so after the engine cooled down I took it off to find that #5 exhaust adjuster came loose so much that I could almost lift out the push rod.

After feeling the rest of the push rods (most turn), I guess many of the other lifters do not have enough preload on them.

Can't believe it ran as good as it did. Not a miss with the #5 exhaust valve just barely opening like it was.

Couple questions:

1. Even though I have adjustable rockers (T&D roller) and the threads looks good on the rockers as on the TA performance site should I get shorter pushrods since the block and heads were cut on ?

2. I have read of doing doing the adjusting two different ways (as was also with the 455 that I am more aware of) and wondered what method is best with the turbo engine ?

 

[dank GN]

Okay so how far are your adjusters down ? For them to be correct you don’t want the adjuster more then 2 full turns down from where the cup is level with the rocker.

 

[earlbrown]

Couple questions:

1. Even though I have adjustable rockers (T&D roller) and the threads looks good on the rockers as on the TA performance site should I get shorter pushrods since the block and heads were cut on ?

The only way to know is to measure what you need and compare it to what you have.

 

[michael evans]

Okay so how far are your adjusters down ? For them to be correct you don’t want the adjuster more then 2 full turns down from where the cup is level with the rocker.

By looking at them (will get a picture before I take it apart) they look to be in a good spot, but it does not RPM well. Meaning that for some reason it hits a wall at 5800 RPMs.

I have the limiters set higher at 6200 RPMs and data log at the track.

Being "new" to the Turbo V6, I don't know them like the Buick 455 V8 that I'm used to. I hate to just throw money at it again to solve the problem.

I need to take it apart and measure every one of the push rods and mark the valve tops.

Not knowing how much has ever been cut off the block and heads, how do I determining the length of the push rod needed ?

Besides the top RPM thing the engine does run very well (does spool up slow I think).

 

[jay dcpt]

You have to measure its the only way to know for sure

 

[dank GN]

Your valve springs are weak . What kinda springs do you have? Seat pressure? Open pressure?

 

[dynoman]

Were the rocker shaft bolts all torqued down ?? I had #5 exhaust valve loose do to the shaft bolt backing out . Heavy duty shafts and supports with stock bolts don't work well . They are too short and pulled threads when I tried to tighten them up. Had to chase the holes and use longer bolts.

 

[michael evans]

Your valve springs are weak . What kinda springs do you have? Seat pressure? Open pressure?

They were new when I had the engine redone 500 miles ago. I will have to remeasure.

 

[michael evans]

Did some investigating to find that the push rods are to short, but how to figure out the right length ?

 

[dank GN]

They were new when I had the engine redone 500 miles ago. I will have to remeasure.

It doesn’t really matter when they where done if the seat pressure is not high enough it will start floating valves and cause exactly what you are describing with it falling on its face past 5,000rpm .

Did some investigating to find that the push rods are to short, but how to figure out the right length ?

You need a pushrod length checker . It’s a push rod that extends and retracts . So you would set the rocker adjuster where it is in the best spot then adjust the push rod checker till you get to zero lash . Then from there you take it out and measure it . Don’t forget that you need to add pre load to the measurement which is usually.050 or so depending on your lifters .

 

[michael evans]

Thanks need part numbers for bee hive springs and retainers.
Can I use the same keepers or they also different ?

Valve stems are 11/32.

 

[michael evans]

Today I borrowed a spring tester from a friend and tested most of the springs (eight out of 12) and they were all over the place. They were from 80 to 110 on the seat.

The heads are not that old and the springs are already in this shape ? I don't know their entire history only that they have gotten hot a few times and it has blown both the head gaskets (long story there).

Questions:

1. What are they supposed to be for a hydraulic roller cam 212/212 duration (seat pressure) ?

2. On the push rods one end has a "bump" on it. What does that mean ? (go up or down)

3. If changing retainers, how does that appect install height for the spring ?

4. Anyone change the springs with the rocker bar still in place ?

 

[earlbrown]

1) It depends on your exact setup. At least 125 or so. And if you're running beehives, you set them using coil bind height not actual poundage.
2) No idea what a ''bump'' is, but I have a feeling you don't want it there.
3) Only way to know is to put it in there and measure
4) Can't be done. The 3 bolts have to be removed and the rocker shaft assembly set aside. (good idea to replace the plastic buttons while you're there)

 

[michael evans]

Earl Brown at the end of the push rods


Good idea on he buttons but I don't have any.

So, on the valve springs I need to compress them the cam lift (comp 212/212) to see what the poundage is and go from there ?


Thanks

 

[earlbrown]

The 'bump' ends go up top. They're for very high lift cams (or, more likely, piss poor rocker geometry). The dip around the OD is so the pushrod can push on the rocker cup at an extreme angle without binding. Buick V6s don't lift don't rotate the rockers that much. ...and with proper mid-lift geometry, you never go that far to one side to need the dip.


On your rocker shafts, you don't need new plastic buttons as you have aftermarket roller rockers. I can't read your ratio on the picture, but if they are greater than 1.55:1 you need to make sure to adjust your numbers for the greater lift.

To find out about springs, if they are conventional springs, you need to measure you spring installed height, and test the springs at that height. Take that number and that's the 'seat poundage'. Then squish it an additional amount of cam lift and that is your 'over the nose' poundage. With those two numbers, you an calculate the actual spring rate of that spring. If your numbers at lower than what the cam needs you can ship accordingly and you're done.

Now with beehives, there's a little more to it. While in the spring tester, you need to squish them until they bottom out. Take that number and add the amount from coil bind the manufacturer wants on them. Then read that poundage. Same thing with 'over the nose' poundage. Once you have those numbers make sure it's not too high or too low for you cam and lifters. If the numbers are way off, you need different springs.

Beehives work when they go close to coil bind. That's how the change their resonate frequency as they're compressed. Spring manufactures say that it's better to be to stiff than to not run them close to coil bind. I have a feeling cam manufactures don't hold that idea as much. ESP if we're talking about a flat tappet cam.

 

[michael evans]

They (rocker arms) are 1.55 ratio. I was thinking if I could leave them in place, it would make things easier until I got to looking how close they are to the springs. By removing them, it will make much easier to change them. I will just have to somehow get them back on that takes patients to get it all lined up.

The push rods were in this engine when I got it. There was no writing on them like the sets you get from TA. They are straight, but very in lengths (from 8.241 to 8.246). I know it is not much, but it makes me question their quality.

On the spring pressures. They were all over the place (from 80 pounds to 110 pounds on the seat).

The recommended pressures are 140 pounds on the seat.

The explanation on the beehives was great and made sense to me.

Thanks

 

[earlbrown]

R&Ring rocker shafts is a piece of cake. They lift right off.

You'll want to pull them anyway to inspect/feel all the rollers and trunion bearings. And check them over or anything odd while you're there.

 

[michael evans]

I agree not hard at all. Just the aggravation of it.

 

[michael evans]

I did come up with a trick to help with it.

Lay them on the bench position them the way they need to be and take a 12-inch wood ruler to hold them in place so the rockers don't flip over.

 

[earlbrown]

..or just squish them together when they're straight and set them on the engine.