Monday, October 20, 2014
Every now and then we get a request to repair the thrust area on a block. What happens is that all the aftermarket companies that sell cams and the related hardware to guys that need to have a roller camshaft sell a cam button that keeps end play to a minimum. What happens is the customer puts in the cam button and does not check cam end play. Then when the cam binds up when the front cover is installed the cam machines a large groove in the thrust area and sends chunks of cast iron though out the entire engine. I figured out a way to repair this a long time ago and have done quite a few over the years. Here is our way of fixing a damage cam thrust on a typical cast iron engine block. First we install a bushing turned up in the lathe to hold a pilot for our seat cutting machine. (this machine is from the 1940's and is built like a tank, It was originally designed to cut seats in flathead engine blocks. we still use it for that but it also has other uses.) I bolt the seat cutter right to the block and machine away the damaged area. Next step was to machine a mild steel insert to fit in the new bore. Normally we would reestablish the height to where it was. The customer wanted to add a Torrington bearing to the mix. The manufacture tells us the dimensions required for this. So adjustments where made to the steel insert and also the cam gear on the timing set has to be machined to a certain spec also given by the manufacturer. After all of this is done we set end play of the new cam button with a straight edge and surface grind the cam button to the required height. The block is now ready for use again. We have saved alot of vintage and racing engine blocks over the years using this method of repair.