A Hot Cutter Cam
RI think it’s good practice to test fit a camshaft before assembling an engine I have machined, and we have all seen camshafts that don’t fit well in the cam bearings. Most of us have had to make a “cutter camshaft” by cutting sharp slots in the cam journals of an old unwanted cam to rotate in the cam tunnel to relief cut the new cam bearings.
Lately, I have seen a lot of camshafts that have journals finished a few tenths larger than the OEM spec. This makes a difficult job of relief cutting the cam tunnel for the new cam because the used OEM cam is often smaller than the new camshaft.
When I encounter this problem I put the cutter cam in my hot tank for 5-10 minutes to get it good and hot. I pull it out of the hot tank quickly and cut the cam tunnel while the cutter cam is hot and expanded.
D and D Auto Machine
No More Broken EZ-Outs
EZ-Outs are too easy to break and the work that it takes to remove a broken one is often worse than removing the original broken bolt or stud. The very nature of the tapered bit can cause additional sidewall tension and does the opposite of loosening a bolt.
I drill the broken bolt with a drill bit that is about .090” smaller than the base thread. Next, I use Torx bits in place of an EZ-Out bit. Pick one that is slightly larger than your hole and drive it in. The broaching action of the star shaped bit driving into the bolt will loosen the threads and pull the bolt in away from the parent hole.
Use the appropriate socket on the Torx and back the broken bolt from the hole. I shop for the cheapest Torx bits I can find and have found tool outlets where you can buy them in bulk.
Hennen Engine Parts & Machine
Green Isle, MN
We live in a time where aluminum blocks with cast-in sleeves are common and we still need to remember to account for how different metals behave.
We build several dozen Gen III and Gen IV GM LS type motors per year. We finish our cylinders .001” tighter on the aluminum block engines to compensate for the additional growth when the block gets up to operating temperature.
This is easily tested. Check your cylinder diameter just before and right after removing from your jet washer. The difference between the aluminum and iron blocks is measurable, and this is only at about 135 degrees (much lower than engine operating temperature).
Cam bearing interference can also be a problem on the aluminum blocks. We always use the new late model cam bearing set developed for the engines with variable cam timing. The diameter is approximately .0005” larger and the added width increases surface tension.
Schwanke Engines LLC
Toyota Axle Jig
Sometimes machine shops are called on to solve more than engine issues. Toyota rear axles are difficult to disassemble and usually require replacing the reluctor gear when replacing the bearings. I made a jig to drive the axle out of the housing using my press. The jig is made from a pipe with a plate welded to one end with holes drilled to match the Toyota hub. The other end has a larger pipe welded to it to “hang” on the press bed. I can save customers a lot of money by reusing parts that other shops replace.
Ralph’s Precision Machine
Pulling Pushrods Apart
We run the valve train geometry on every single engine we build. Every once in a while we get in a time bind and need pushrods ASAP. It is for this reason we keep extra sets of push rods for the popular engines on hand. For emergencies, we keep some longer than normal three-piece pushrods and shorten them as needed to expedite deliveries. Shortening pushrods in a lathe is pretty easy and doesn’t take long, but removing the push in ball ends can be.
We’ve tried dowel puller collets, collets in our mill and a host of other ways to remove the ends. The easiest way we have found is to make up a few different width cut-off tools ground into high-speed steel tool bits.
We start the cut right under the ball end and cut the tube to the shank of the ball end. This leaves a nice groove to grab the ball end with a small bearing splitter held in a vice. We use the collet in the dowel pin puller on the pushrod itself so there’s a lot of area for it to grab onto for pulling.
You don’t have to worry about nicking the shank of the ball end, as they are harder than the high-speed steel tool bit that we make the cutoff tool from. You can cut the rod to length once the ball end is removed, or make the tool exactly as wide as you need to shorten the rod.
You can’t just drive the ball end back into the pushrod after it is cut. There needs to be a slight chamfer inside the pushrod to clear the radius between the shank and ball end.
Tuf-Enuf Auto & Marine
Addressing Connecting Rod Small End Issues
When dealing with piston pin ends of connecting rods, we have found a countersink to be a very useful tool. Attempting to guide a piston pin into a bushing with only .0001-.0005” clearance can be a frustrating task, occasionally resulting in damage to the edge of the piston pin or the bushing. To make pin installation easier in the finished bushing, prior to machining, we will use a countersink in a drill press to give the bushing a heavy taper. This helps to easily guide the pin into place, and this same tip can be used as it applies to installing piston pins on press-fit rods as well.
We also use this method when replacing bushings on rods, where the rod itself has little to no taper. Pressing in a bushing against a non-tapered steel wall can cause the bushing to crush, distort, or shear off material, leaving it loose in the bore. Another way it’s helpful is to dress up the edge of a bushing or rod and prevents the pin from passing through.
It is VERY important to note that when even lightly using a countersink, the pressure will leave a slight raised ridge on the leading edge of the surface you’re cutting, which can be easily removed. Use a mandrel or wrap a 240-grit emery cloth over a mandrel that’s extended out to where the edge of the rod will barely start over it, thereby polishing only the very leading edge (.002-.003”, or just a few rotations of the mandrel is generally enough), and leaving the rest of the bore untouched. Of course, using low pressure and letting the tool do the work will minimize any ridge created. It’s not uncommon to have “chatter” at first, but simply working off the rough edges on a couple of junk rods will usually smooth it out.