Is there an engineer in the house?

[David K]

Ive posted this over on zcar.com, but we all know the chances are greater for debate over here.

 

Ive finished by teardown and evaluation of the P90a head with hydraulic valve adjusters. This took me a total of 2 years. I am 100% positive that a non-stock spec camshaft CAN be used in the p90a.

 

Ive completely disassembled each hydraulic valve adjuster. Each adjuster contains 1 casing/cylinder, 1 cap that holds everything inside, 1 plunger, 1 pressure release valve, and 1 small spring. Ive honed the inside of each casing and i am now ready to put them all back together.

 

Thus, my concern. I am looking for a spring made of metal that will withstand high temperatures, OIL, and repetitive compression. The spring is about 1" long, and 1/8" in diameter, so its not very big at all. I am positive after my research, that a non-stock camshaft can be run in the P90a head if these springs are replaced with a much stiffer set.

 

Machine shops and industrial supply shops are of no help. Who woulda thought? Im glad i did my research and my build, it puts years and years of debate on the P90a hydraulic head to rest. Some of you may remember me doing this in the past. Search "hydraulic" and "P90a" for more info!

[Jolane]

David,

Well, I play an engineer in real life...but may not be able to help with this. I will give it a shot though.

I am not familiar enough with the P90A heads, I have a P90. The spring that you are referring to, does that somehow hold the "lifter/valve adjuster" open so oil can get inside and pressurize the chamber, thus eliminating lash? If this is the case, I believe that the oil pressure is what supports the load of the cam, not the spring. Replacing the spring will probably not have any effect on the whether or not a more aggressive cam can be run, only the oil pressure. Perhaps though the spring plays a role in the valving of the oil flow, I don't know. My gut feeling though is that changing this spring will not change how a more radical cam will run. Just a feeling.

So, to answer your real question though, you can find precision springs in McMaster Carr. go to http://www.mcmaster.com and search for precision springs. For a stiffer spring, increase the wire diameter. You will have to balance this though with compression height, paying careful attention so that the spring does not bind.

If you don't find the spring you need at McMaster, I would recommend Century Spring Co (http://www.centuryspring.com/). I don't know if they have a minimum though.

Hopefully this information will help.

Joshua

[awd92gsx]

LOL...

 

Go for it Ghostiee!!!

[Guest szlash280z]

I think you're full of cr_p. I am 100% sure you know not what you speak!

[JMortensen]

My gut feeling though is that changing this spring will not change how a more radical cam will run.

Yep. Those little tiny springs couldn't possibly be what holds the lifter in contact with the cam lobe. They just hold them open when you shut the engine off so they don't bleed down, that way it doesn't sound like a diesel on startup. That's my understanding anyway...

[Jolane]

Thanks John for clarifying that. I wasn't sure if they were like a regular hydraulic lifter or not.

Joshua

[David K]

Howdy,

 

Thanks for the replies guys. The idea i have is to replace the stock spring with a very thick and strong spring, hard enough you cant push down by hand, kind of like the valve spring itself. I didnt mention ive opened the oil passages to the next size drill bit i could find. Im hoping to get into the turbo automatic oil pump i have and see how i can increase pressure to the adjusters.

 

Jmortenson, i understand what you are saying and i agree. My idea was to change the stock spring to actually give the oil pressure a little support to lower the amount of bleed at high rpm.

 

It will be a few weeks to a few months until i can try this out. A user at zcar.com suggest i call a camshaft specialist and talk about a hydraulic grind. Thats a good idea!