new cam = new valve springs?

Through talking with an aquaintance i was told that if i wanted to change cams from what is in there now to the comp cam (234-4) i would need to change out the valve springs in the head while everything was being gone through. I have no idea whether or not this is correct and am looking for some guidance on this.

 

Re: new cam = new head springs?

Might as well, cheap insurance. Springs get tired and metal fatigued too.

 

Re: new cam = new head springs?

From my engine rebuilding experience. When you change a cam you must change the lifters. I'm not to sure about valve springs though.
Ryan

 

Re: new cam = new head springs?

Shouldn't be "required" unless they're worn out. But, as Ron said..cheap insurance. It's kind of a might-as-well.

 

Re: new cam = new head springs?

How much extra money are ya talking about here? Vs. the possible poor performance from weak springs, or worse, a broken spring later on? I was taught to just replace things like that when you have the chance, if for no other reason than piece of mind. They're usually pretty cheap in the big scheme of things.

I rebuilt a Harley motor once that had a broken inner spring that I didn't even know was bad. The outer spring had smashed and broken the inner spring into a zillion pieces, which of course were throughout the motor, it wasn't pretty. It was an inner spring from a Sportster motor that someone had put into a Shovelhead, and they're not the same, so it died a horrible death. I found it before it destroyed the rest of the engine, but one piston was ruined, had a big groove gouged down one side.

One of the good things about taking everything all apart and checking things out real close is the fact you might find something that doesn't belong there. You could also have your springs tested at an automotive machine shop, most good ones should have a valve spring tester that measures the spring tension.

 

Re: new cam = new head springs?

I would find a machine shop with a spring tester and have them checked. If they are all within spec i would use them.
I have put used springs in many engines and havent had a failure yet.

If you were going to put a more radical cam or higher ratio rockers in it i would change them but the one you want to use doesn't have that much valve lift.

RSN

 

If you have them out and they are all different heights, then I'd certainly replace them. I'd think you could rig a spring checker easily with a bathroom scale, drill press and ruler. The springs have a pressure spec in lbs at a specific height.

Stock springs shouldn't be very expensive, so I wouldn't need much of a reason to replace them.

 

The timming gears and chain may not be worn out, it depends on how many miles is on it.The thing about it though you have to take it off anyway to get the cam out. I would just get the complete kit and put all the new parts in it. One thing that all engine builders will tell you is you never put a new cam in on old lifters. I dont belive it matters on the roller type lifters but the flat tappet hydraulic lifters need to be new if going with a new cam as I have read and heard old lifters are not good for the new cam lobes. If I was doing it, I would go with cam,lifters,springs, timming gears and chain is up to you. I would replace it since it will be down that far anyway.

 

It is possable that your aquaintance was refering to the need to upgrade valve springs due to the aftermarket cam. This is a necessity on high lift cams that require special springs that won't bind under full lift. With this exception, valve spring replacement is usually catagorized under head jobs, not cam replacements.

 

What's the part number for that kit Sparky? I'm looking at summit now, but can't find the kit for the life of me. Do i need to look for an odd-fire 231?

As for the motor, it's headed to the machine shop. The heads are going to be checked out and gone through as well. I would assume if something was wrong it would be corrected, especially wih the one year warranty on all work done.

Nevermind Sparky, I've figured out the link and the kit needed.

 

I talked to Summit about your cam a couple weeks ago and unless you buy the kit (cam/lifter) the $118 Summit price for the 252H (I believe) was cam only. When I called the woman told me the cam and lifters was around $189. She never mentioned the "kit" you guys were talking about but I'm sure they've got it.