After rotating the crank to get the rods for cylinders 1 and 2 out of the way, the cam bearings are lightly lubed and our cam is carefully slid into the block. Since we're just checking clearances here, the flat-tappet cam lobes are left dry for now. During final assembly, they'll of course need moly lube for proper break-in.
Cam-lobe-to-rod clearance can only be properly assessed when the crank and cam are turning in correct phase with one another, so our timing chain needs to go on. Crank sprockets can sometimes be difficult to install, and it's a bad idea to just hammer it on.
Our PN POW101525 Crank Gear Installation Tool from Powerhouse Products is inexpensive ($15.95) and easy to use: a run-of-the-mill harmonic balancer installer tool is used in conjunction to press the sprocket on safely and evenly.
The crank and cam are turned so that the dots on their respective sprockets line up vertically, and the cam sprocket and double-roller chain can slip on (more on the timing chain and cam we've chosen next time). We used some old bolts because this author forgot to purchase cam bolts for this project ... we'll have them in our hands for next time.
Because clearances can change as an engine is warm and/or operating at high rpm, simply installing piston/rod assemblies one at a time and turning the crank over may not reveal any rod-to-cam interference whatsoever. But add a fast-spinning, hot crank into the mix, and you may get slight crank expansion and stretch and make contact. Therefore, a thin layer of clay, in this case, Play-Doh, is applied to the cam lobes that will come near the rods. The engine is spun and the clay inspected: no marks, no problem. In our case, some rods needed extra massaging to afford the proper clearance, and we performed the same amount of grinding on all of them just to be safe.
Another important clearance to check is rod side clearance. This spec can be checked with a feeler gauge, and we found ours to be within Powerhouse's recommendations. By the way, when building a stroker it's also a good idea to set your pan atop the upside-down block and spin the engine to check interference-we're using a stroker-specific pan though, and we don't anticipate any problems (more on that next time). With all appropriate clearances checked, we can move on to other things, so all rods as well as the cam are removed. Make sure you get all the Play-Doh out before it dries, as the stuff can harden into harmful particulates.
It's time to move on to piston ring fitting. Some handy tools to use during the fitting (and later installation) process are these available from Powerhouse Products. From left to right, they are: Piston Ring Expander Pliers (PN POW105060, $9.95); Piston Ring Squaring Tool for 4.000-4.230 bore sizes (PN POW105002, $24.95); and Adjustable Tapered Ring Compressor for 4.000-4.090 bores (PN POW106020, $35.00). Not shown, but also needed, is a ring filer. You can grab one from Powerhouse Products as well. It'll help you get the rings to size quickly and keep the edges straight.
Our Powerhouse stroker kit's piston ring set was inclusive of moly top and iron second compression rings, both of which need to be gapped. A ring is slid into a cylinder, squared, and the end gap measured with a feeler gauge. As expected, the gap is too tight and does not afford the 27-28 thousandths recommended by Powerhouse. Numerous trial fittings will be needed for each ring; file too far, and the ring is garbage. Remember to deburr when you've got it to size, and label each ring with masking tape as it's a unique fit to that particular cylinder.