Are there any valve spring experts on this forum, I have an issue?

Engine is a 350 Olds with decked block to bring compression down to 9:1. Everything else to close to stock, has big 455 valves though.

My engine builder - he machined and set everything up but I assembled to clarify, seems to have not taken steps to setup my valves correctly.

Engine runs well but has quite a bit of valve float or clatter and it takes a long drive to settle down. Adjusting valve train is a disaster and one rocker arm had dropped off the pushrod when I checked last week. Took off the intake manifold and some hydraulic lifters were hydrolocked and some had movement - makes it hard to adjust like that. The lifters and cam are ok with no wear - pulled engine to figure it out.

Engine builder purchased a set of springs and keepers etc off the shelf. I believed that the valve height was always set by measuring between spring seat and retainer?

Here are my measurements using an outside mic for the spring and a height micrometer for the height check.

Measurement of spring using micrometer
2.217"

Measurement of installed height using height micrometer
1.860"

This is the factory installed height as per Rockauto site but this is with rotators.
Height 1.960

Sorry for the long post, depending on feedback I will take back to engine builder otherwise will sort out myself.

Based on the issue, should I :
- purchase longer springs with correct open height and spring rates
- if I cannot locate longer springs, source shorter ones and add shims

Thank you for any feedback.​​​​​​​

 

I think the first thing I would do is get a good straightedge and put it across all of the valves and see if they are pretty close to the same height. The correct way to check the height is with the Oldsmobile tool but not many people have one. It sits on the valve cover rails.

 

Thanks Bill, neat old tool - I will have to use a flat edge. Pretty sure they will be ok but of course I should elminate this too.

Graeme

 

Your problem really does not sound like a valve spring problem to me but you never know. Dont know what you mean by valve float or chatter. Valve float is something that typically happens at very high rpms. The "chatter" might be lifters. I would be mainly concerned as to why the one rocker arm came off ? What rockers are you using ?

 

Hi Bill,

thanks for the response.

There were some lifters that were fully pumped up when I removed them while some moved freely. That's what I mean, not consistent and adjusting valves was interesting!

The rocker arm was attached but pushed to one side and the pushrod was swinging in the breeze. Rockers are the CompCams Magnum Rocker Arms in their kit.

The noise I mentioned we thought was pre-ignition but it would go away after a long drive....when lifters all pumped up?

Cheers.
Graeme

 

Thanks for the responses, I did more research and found the following ...

- engine builder by a stroke of luck purchased the correct springs. They were Lunati and it took a while but I found the installed height of those are 1.660

- As documented in many Oldsmobile sites, the installed height of all valve springs is 1.670" regardless of retainer style.

- the problem now is I am left with a measurment with the height micrometer of 1.860" giving a difference of .200" to shim!

Based on this, I will contact the engine guy and ask for his suggestions. Are there options you think I should suggest to him do you think? (longer valve springs maybe)

Again, I misread the information on how to measure the installed height. You need to know the installed height of the valve springs first then measure using the mic tool. I did not realize the spring will extend a lot further...sorry about that.

Graeme

 

Are you using hydraulic flat tappet valve lifters ?
How was the rocker arm able to be pushed to one side ?
If you are using hydraulic lifters, they should literally "pump up" within seconds, after the engine is started.

Graeme, you appear to have some misconceptions.
1. Your engine guy probably didn't get lucky picking valve springs by a stroke of luck. What is the spring pressure at the installed, valve closed height ? At what spring height do you get "coil bind" ? Do the valve retainers clear the valve guides at full cam lift ? Whats the camshaft lift at the valve ?
2. All OLDSMOBILE performance valve springs (from Oldsmobile) are installed at 1.670" for old NHRA stock class engines. Other manufacturers can have valve springs that install at different or the same closed valve heights. This depends on wire size and several other factors that affect s[ring pressure.
3. .I think you need to ask for advice from your engine guy, not suggest "options" to him. You still have to figure out the problems with: A. Valve lifter oiling, B. Valve lifters not functioning, C. Rocker arms turning to the side and push rods swingin in the breeze. .

 

Let me add this--regular shims tend to get chewed up by the valve spring dampeners, so if you want to take up about 0.2", start with valve spring cups such as Comp Cams offers. They are hardened. Also there are different valve retainers for different installed heights available aftermarket, One example is the Isky chrome moly 507ST and 507STA, with the latter giving 0.060" greater installed spring height. There are also different split locks available to change installed height. Or, get different springs designed for the Olds heads that came with rotators but have them removed for an installed height of 1.88".

 

Graeme,
How are you measuring the valve spring installed height ?

 

Hi Bill, Measurement using height micrometer. ..'

Valve springs installed height I found the specifications here - https://www.jegs.com/i/Lunati/638/73262-1/10002/-1

 

Thanks for that info - best if I take heads to the engine builder at this stage. ;-)

 

Specifications of the valves here - https://www.jegs.com/i/Lunati/638/73262-1/10002/-1
Camshaft specs Lift: .425''/.425" Duration: 252°/252°
I will have to work out the other questions.

.I will ask the engine guy for advice, obviously I know jack about this stuff - but learning --- thankyou you for your feedback.

BTW - bit hard to trust the engine builder as he destroyed one of my heads trying to put in Chev hardened valve seats when I told him they would not work. These heads are difficult to source in Australia.