Got a worn-out small-block sitting under your weekend cruiser's hood? Or is your 350 running fine, but just not putting out enough torque to satisfy? Sounds like you need a fresh mill with more cubic inches. There are a few options on how to get one. If you have the dough to spend, you can very easily get a shop to build and install a fresh big-cube engine for you, soup to nuts. If you're willing to do a little more work, you can save some funds by pulling that tired engine yourself and dropping in a fresh stroked crate motor.
The final option to consider is pulling that old mill and rebuilding it on your own. Done correctly, the do-it-yourself method can save you thousands, provided you've got the time and patience to put an engine together from scratch. We're about to do just that, with an eye toward achieving the lowest dollar-per-horsepower ratio humanly possible out of a small-block Chevy. Aside from the cash savings, we'll show you that rebuilding a small-block and adding displacement isn't as difficult as you might imagine-and it could actually be fun.
Powerhouse's basic 383 stroker kit for two-piece rear main seal blocks retails for $499, a
The foundation of our build will be a rotating assembly made by Bakersfield, California-based Powerhouse Engine Components. This self-professed "home of the 383 stroker kit" retails some of the most affordable small-block engine assemblies in the country, and this fits the theme for our build perfectly. We were intrigued by the bargain basement prices we saw quoted in its ads. Just how much Mouse could we build on an editor's budget? (We should note that if you're intimidated by the build techniques shown in this story, Powerhouse also sells affordable complete long-blocks that carry a three-year unlimited mileage warranty. See the company website, enginekits.com, for all of its product offerings.)
Any do-it-yourselfer will need some tools to help him or her in an engine assembly endeavor, so we've enlisted the help of Comp's tool division, Powerhouse Products (no relation to Powerhouse Engine Components). You'll see some of the company's reasonably-priced tools highlighted along the way, and boy do they come in handy. Other manufacturers like ARP have signed on to help out with some strong-yet-affordable items, and don't be surprised to see a few others when we continue this build in subsequent issues. That said, on to the short-block.
The niftiest rotating assembly in the world is nothing without an engine casing to put it in. We decided the added stress of a longer-throw crank would make a 4-bolt 350 block appropriate, so $200 grabbed us one from local Jersey shop RPM Performance Engines. Another $514.27 got us a full cleaning, 0.030 overbore, align hone, and cam bearings and plugs installed.
Pre-assembly is probably the most important process in an engine build, and the fact that our block had been align-honed made verifying bearing clearances even more critical. We first pop the upper shells in place in the block. Our cast 3.75-inch crankshaft is what will give us the extra 33 cubes over what a stock 3.48-stroke crank affords, and here we carefully drop it atop our bearings (which are left dry for the moment-we're not spinning the crank over yet).
Tried and true, Plastigage has been the bearing clearance measuring tool of both pros and do-it-yourselfers for quite some time. A strip is carefully cut and placed across the width of each main journal, and the main caps then torqued atop. With the caps removed, we note a bearing clearance between 0.0015 and 0.002 of an inch for all mains, which is within Powerhouse's recommended acceptable range. The procedure for measuring rod bearing clearances is virtually identical, and with these steps done, we can pull the crank back out of the block.
We're not through checking bearings clearances just yet, because while out-of round crank journals might measure up just fine with Plastigauge, they'll deliver uneven tolerances around the journal circumference. A micrometer kit like Powerhouse Products' PN POW152004 will help you achieve precision measurements down to one ten thousandth of an inch for only $109.
We weren't worried too much about the roundness of our journals since we were using a new crankshaft, but those who might be using remanufactured or turned cranks in their strokers should definitely double-check theirs.
The other half of the clearance equation is rotating clearances, that is, making sure your rotating assembly will spin in the block without hitting anything. While good practice in any engine assembly, this step is doubly important when installing a larger-than-stock crankshaft, as is the case here. After cleaning all main bearings of Plastigauge residue and lubricating them with oil, the crank is reinstalled and tightened in place (using some old main bolts for now). After the thrust bearing is properly set, it will spin; if not, you probably need an align honing.
A Pro Crankshaft Turning Socket from Powerhouse Products (PN POW103050, $26.25) makes an easy task out of spinning a small-block's crank-and there will be quite a bit of it to do both during pre-assembly fitting as well as final assembly. Its knurled removable nut also means a degree wheel can be easily attached, a feature that we'll use to our benefit next time.
This Powerhouse kit uses press-fit piston pins, so installing the rods on the pistons is not possible without the appropriate machinery. We took ours to our machine shop and had it done for $42.81 with tax. This takes a step out of the assembly process for the do-it-yourselfer, but also costs a few more bucks.
With some lube on the cylinder walls, the piston/rod assemblies for cylinders 1 and 2 are installed one at a time (no rings are necessary for now, but lubed rod bearings are a must). Having both rods on each crank journal will hold the rods where they're going to ride while the engine is running. Otherwise, the rods can shift and you'll get a false clearance reading between the rod nuts and the block. Also, don't just use two arbitrary piston/rod assemblies and swap them between cylinders: manufacturing variation makes each unique, so mark each one so that it can be placed in the same location during both pre-assembly and final assembly.
Upon spinning the engine over, we noted some close calls between the rod nuts and the engine block just above the oil pan rails. Though most blocks have factory notches in this area (as this one does), they often aren't deep enough to clear the rods when a larger crank is installed. We'll note this interference area with a magic marker so that some light grinding can be done later-we'll hit the nuts a little as well. This process must be repeated on each and every cylinder with that cylinder's particular piston/rod assembly installed.
Before marking clearances on the rest of the cylinders, we take a peek into the cam tunnel and make an important discovery: the rods of cylinders 1 and 2 protrude into the cam tunnel substantially, making contact with cam lobes a distinct possibility. This is yet another important concern when building a stroker, as the increased crank throw pushes the rods closer to the cam. Though engine outfits like Powerhouse often clearance these areas of the rod for you (you can see the ground surfaces here on each rod), it's still a good idea to double-check. We therefore decided we'll need to install the cam and leave it in while we check clearances for all the rods.
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.
We're done fitting the rotating assembly and are just about ready to put this thing together for good. Before we do so, we need to lightly grind the block at the locations we marked earlier. The block is carefully masked to prevent iron grindings contamination; even though the next step is a thorough cleaning, there's no sense in making our job more difficult. This is a typical stroker step, but use care not to go too far and ruin your block.
An engine cleaning kit like this one from Powerhouse Products (PN POW351307, $29.95) includes brushes of all shapes and sizes in order to enable scrubbing of all possible holes and passages in your block and crankshaft.
We do exactly that, and, in addition, all surfaces of the block are wiped with quality towels soaked in mineral spirits.
After a good cleaning themselves, our main bearing shells are put back in place in the block and are lubed with some gooey red Clevite Bearing Guard, a high-pressure protective lubricant available from Powerhouse for just $3.99. We'll also use this same stuff on the rod bearings when the time comes, as it offers excellent protection at startup.
With the upper half of our two-piece rear main seal in place (and with a light amount of RTV silicone used on its mating surfaces and in the surrounding block area), the crank now drops in place for good. The main caps can then be placed atop it-make sure they're in the correct place and orientation, and that their bearing shells are adequately lubed.
To secure our main caps, we're using ARP's High Performance series main bolts (PN 134-5202, $42.35 for four-bolt main engines). An excellent upgrade over the stockers, these 7/16-inch units are rated to 170,000 psi and will be able to handle the extra stresses incurred by our longer-throw crank.
After making sure to use plenty of moly assembly lube on the threads and on the washers, the bolts are installed and torqued to ARP's recommended 65 lb-ft.
With our crank securely in place, we can turn our attention to installing the piston/rod assemblies one by one. First the rings must be installed and clocked. The oil rings/rails can be installed by hand (shown), but our Powerhouse Products ring expander comes in handy for the compression rings: it prevents ring twisting and potential damage to the rings or the piston.
Before dropping the pistons in and hiding the lower cylinder walls forever, take a look at the casting area that has been removed at the bottom of some of the cylinders. This clearancing is especially common practice for blocks accepting stroker internals, as it affords a little more room for the rotating assembly. Make sure your machine shop has taken care of this for you if your block has material in this area.
After the cylinder wall is given a good cleaning, it's lubed with engine oil and our Powerhouse Products ring compressor is adjusted to size and set on top. The piston is carefully started on its journey with the butt end of a hammer.
Any significant resistance could be a ring hanging up; if this happens, pull the piston out and start over-don't risk breakage!
The rod cap (with at least one nut) is then installed loosely beneath in preparation for flipping the engine over. Note how we've clearanced the rod nuts that come closest to the block: you can see this on the upper nut of the rod labeled "1" that we've already installed. This is a must-do for nearly all strokers and shouldn't affect engine balance.
With the engine flipped over, the ARP rod studs and nuts are lubed with moly assembly lubricant and torqued for good to Powerhouse's spec of 50 lb-ft. Keep at least one nut on at all times while adding lube so that you don't accidentally send the piston to the floor.
The piston/rod installation process is repeated for all cylinders, and with the bottom end of our shoestring stroker fully assembled, we're out of time. Next issue we'll build upon our short-block success and add some more strong-yet-affordable components that will help ensure reliable power on a tight budget.
Powerhouse Engine Components
931 19th St
RPM Performance Engines
Automotive Racing Products (ARP)
531 Spectrum Circle
3402 Democrat Rd.