My good friend has been having a problem with breaking pushrods. When we rebuilt his motor last winter we did the following: 355 LT1 (.030 over), stock crank, stock rods (resized with ARP waveloc bolts), Speed Pro -22cc pistons, stock heads springs lifters and pushrods, new stock timing chain, 1.6:1 self aligning Proform Roller Rockers, custom Cam Motion Cam.

A few months ago he broke 1 pushrod on an intake valve. we replaced all 16 pushrods with Comp Cam stock replacements from Summit. They said they were like .005 longer than the stock pushrods. The car has been fine for a few months until yesterday. He broke 5 pushrods and another 3 were bent. Shift points are set at 6K rpm, and he hasn't reved past that, and didn't when it broke. Valve train geometry looked fine the last time we put it back together. What is going on here? I'm having him look right now at the cam specs, I didn't think it was anything to radical, but could he be experiencing some valve float and or coil binding? What kind of lift are the stock springs good to? BTW this is a 94Z A4 with a Turbo Tech kit with the 60-1 HiFi with a front mount intercooler.

Bill

 

Ok I have the cam Specs. Based on a 1.5:1 rocker it is 208/202 duration and .457/.446 lift on a 114 LSA. with the 1.6 rockers if i did my math right that would be .487/.475. This cam has 22.8 degs of overlap, which I thought was kind of weird for a turbo cam. I started looking at my specs and I guess it looks like I have only 4 degs of overlap. Is this to much lift for stock springs?

 

Upgrade the valve springs. I broke several until i got better springs.