Hey guys,

I broke yet another valve spring last night after having the shop tell me they reset the valve lash to the Cam Card specs. I'm not spending another $400 so they can screw around in my engine. How hard is it to install a valve spring and set the valve lash on it? What tools will I need and what, if any specialty tools will I need? Thanks.

 

I'd find out why you're breaking valve springs first. Breaking one is common. Breaking a few in a short amount of time tells me something else is wrong.

Are you getting spring bind? Are the heads set up for the amount of cam lift?

Changing a spring is similar to changing valve seals. You'll find many links on how to do that. The best way to change a spring is using a compressed air source. With the cylinder that needs to be replaced at TDC, an air line adapter is installed into the spark plug hole and compressed air is forced up. This will hold the valve up when the spring is off. An "on vehicle" valve spring compresser is then used to compress the spring so that the keepers can be removed.

There is no valve lash on a spring but there is an installed height. Valve lash is set by the rocker. Since you mentioned cam card, what are the specs of the cam and what springs are you using?

 

The Cam is a Lunati 60121 (summit number LUN-60121) and I purchased the recommended springs to go with it. The heads are World Sportsman II heads and the shop I had the motor built at assured me with what I had it would be enough for the cam lift. Maybe he was mistaken? Anyway, I will post the cam card once I get it scanned. Have to go shopping with the wife first though. When the first one broke, I didn't know what was wrong until a shop found it for me...they said the lash had been set way too tight when he installed the new spring. Could that being too tight have weakened the other springs?

 

Cam card is available on Summitracing. This is a hydraulic cam and valve lash should be the same as any other hydraulic cam. Being out a little bit in either way won't change how much the valve opens. If they overtightened the rockers then all kinds of bad things can happen.

Max lift .515/.530
Basic operating range is up to 5800 rpm
Recommended valve springs have an installed height of 1.75"
All the sportsman II heads have a recommended installed height of 1.81" to 1.90" so your springs should have been fine if they were shimmed up to the 1.75" install height.

If everything was set up properly, I see no reason why that setup should have broken any valve springs.

I broke a valve spring last year and I know all my components are within tolerances. The only thing I was doing wrong was to use a slightly weaker double spring instead of a recommended triple spring. Spinning my engine to 7500 rpm with an aggressive cam can be hard on valve springs. Your cam and rpm range shouldn't be causing a problem.

 

And that's the issue. I don't know what is going on. The shop that built it is one of the most reputable shops in the area and even builds engines for some of the guys at the local tracks called RMR and Miller Motor Speedway. I can imagine one breaking, it happens. Two? Maybe I got a weak batch or...if he didn't follow the cam card correctly, maybe overtightened the springs thus weakening them?

I still have to pull the valve cover to actually see if one broke or something just came loose as didn't get a chance to tonight. I'm going to do it first thing after work tomorrow. Could it be possible that the nut on top came off?

 

Definitely a broken spring. Number 1 cylinder...damn.

 

Change them all.