[70chevelle15]

I have a stock goodwrench motor and would like to make a cam swap. I want to install a cc xe262. I was wonder how difficult it is to install some z-28 valve springs on these cylinder heads. I will be taking the heads off anyway in order for a thinner head gasket to in. If it required too much work how much do shops ussually charge on a job like this. Thanks

 

[baddbob71]

Off the engine and on a bench it will take no more than 20-30 minutes to change out those springs, so take this into consideration when talking to the machine shops. Or better yet, buy or borrow a valvespring compressor and do them yourself. You might want to install new valve seals while it's apart. Bob

 

[70chevelle15]

Are there any other tools needed or other perks required. I just want to use the standard z-28 springs good to .490 lift. Cause this sounds easy.

 

[joespanova]

Guys........I dont think ya' can do this job in twenty minutes

You'll need a height mic,shim assortment and make sure ya' have the right retainers.In a nut shell, know installed height and coil bind height.

 

[70chevelle15]

I was actually considering the comp cams xe256 k-kit with all the springs, locks, valve seals and retainers ready to go. For 300 bucks looks like a good deal, maybe make it simpler by having all the parts I needed.

 

[Fuji]

You really need to know what you are doing to swap your own valve springs. As was mentioned above you'll need a height micrometer, and a spring compressor. If you have to buy these tools they'll cost you around $100.

Step number one is to find out from the cam manufacturer what your seat and open pressures need to be. Then you need to determine your installed height. Subtract your valve lift from the installed height to determine the coil bind height and add .050" for safety margin. Now you've done the easy stuff.

The real challenge will be to find springs that will work with your installed height to give you the proper pressures and coil bind height. If you're lucky you'll find something. Now you've got the springs - how do you know they meet the specifications? You'll have to have them tested at a shop. Now suppose they don't meet the specs and they won't work with your installed height? You'll have to send them back and start all over.

I'm going through this right now and believe me -if the heads were off the car I wouldn't even think twice about having my local shop do the work.

As a side bar, I wish the spring companies would stop advertising how much lift a spring is good for. It is a meaningless number and I'll bet a lot of engine builders have gotten in trouble using the advertised number. The lift that a spring can handle is determined by installed height and coil bind height. A spring that coil binds at 1.2" and is installed at 1.7" is only good for .450" of lift with a .050" margin. That same spring installed at 1.9" is good for .650" of lift with the same .050" margin. Just my $.02.

Chris

 

[baddbob71]

20 minutes was assuming the installed height was known and right and the retainers are being reused , I've done them in 20 minutes a couple of times

. 45 minutes in the car .

 

[70chevelle15]

Ok Ok, i'm only 16 but I think I can figure this out, and if nothing else I'm just learning something new. Here's the valve spring specs:

Outside Diameter of Outer Spring (in) 1.254
Coil Bind Height (in) 1.150
Spring Rate (lbs/in) 417
Inside Diameter of Outer Spring (in) .880
Inside Diameter of Inner Spring (in) .820

Ok So the max lift with the cam I'll be running is .454 on an xe256 cam. Now If I ran this spring at comp cams recomended height of 1.7 it would bind at 1.150
Now with my lift and .050 margin I would be sitting at 1.196 at full lift. Now I'll need the micrometer to see how hight the spring needs to sit at, but from a few other source's I have found that the goodwrench heads are set with a valve spring height of 1.750. This meaning I would need a .050 shim to match that height, right?. I would still double check the height but I'm pretty sure that's what it is, then I would have 1.246" at full lift. That leave's .096 margin on top of the .050 margin that is recomended. If this was the case then I could get away with using these springs with plenty of room right? or at least theoretically?

 

[70chevelle15]

Oh ya Thank you for the in depth response Fuji and everyone else, It's greatly appreciated. By the way those valve spring are recomended by comp cams and are included with the kit.

 

[Fuji]

Yep. Your math is correct. With only .454 of lift you should be okay -if the spring actually coil binds at 1.150. It would be a good idea to have them checked just to make sure they are right. If you ever get into higher lift cams you'll have to be a little more careful - coil binding springs will ruin your day real fast. And never trust anyone with your engine. Always double check your parts and any machine work to make sure everything is right. I'm sure there are hundreds if not thousands of stories on this board alone about wrong parts or bad machine work ruining engines. A friend of mine got Chevy lifters in his Edelbrock cam kit for a F**D Windsor. Can you imagine the results if he hadn't noticed?

Good luck!

Chris

 

[Eric68]

Originally posted by joespanova:
Guys........I dont think ya' can do this job in twenty minutes

You'll need a height mic,shim assortment and make sure ya' have the right retainers.In a nut shell, know installed height and coil bind height.

Exactly. If you do it right you will have at least a couple hours doing the springs on the bench. At a minimum you will need a compressor, a height mic, and a bunch of shims. Just swapping in springs is a bad move -- installed height will make a radical difference is spring pressure.

 

[70chevelle15]

Trust me my idea here wasn't to get this job done fast. I would take my time any way, especially for something as vital as this. I'll probably order the kit then have the springs tested just to be sure. I love learnin new stuff. Thanks guys

 

[Guest]

Let's see, a 2" finish nail cut and filed to fit along with my 6" dial calipers tells me the retainer height..

pdq67

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[70chevelle15]

nice

 

[joespanova]

Very nice