Check the spark plugs for signs that the engine was burning oil. Avoid engines with oil-contaminated plugs, but don't assume fresh plugs are the ultimate sign of a well-preserved motor. If the oil and plugs pass inspection, try spinning the motor over with a ratchet on the crank pulley. If it spins freely with no binding, chances are the bearings are in good shape. If you are allowed to bring a battery in to crank the motor over, by all means perform a compression check.
With tool chest in hand, we headed off to the wrecking yard in anticipation of pulling a small-block. Our trip was very successful, since we spent the majority of our time negotiating with the owner rather than knee-deep in used oil and tranny fluid performing an engine removal. This particular wrecking yard had a few engines already pulled and awaiting new homes. We happened to come on $200 Tuesday, which meant that any complete motor was available for just $200.
As luck would have it, this even applied to the ones previously pulled sitting in impound. Though there appeared to be one or two good carbureted candidates, what caught our eye was a pair of complete TPI motors, one iron headed and the other equipped with aluminum heads. Not surprisingly, these were set aside and were not available for the $200 price tag, but we were determined. A discussion with the owner revealed that the aluminum headed motor was indeed an L98 pulled from a Corvette (circa 1987) and the iron-headed piece was a 305 from an IROC Camaro. The owner wanted $750 for the aluminum-headed L98, but only $450 for the 305 TPI (both well out of our price range).
Upon inspection, we discovered that the iron-headed small block was actually a 5.7L (350). We never mentioned that to the owner, but instead offered him $200 and allowing him to keep the TPI system, which was not useful for our needs. Not only did we get him to finally agree, but we got him to throw in used Holley 4-barrel carb (in need of a rebuild). Sweet!
The iron-headed TPI motor was quite a find, as it ensured we had a hydraulic roller cam and a decent compression ratio. The heads were to be replaced with low-buck aluminum castings (that's right, an aluminum-headed, 400hp small block for $1,000).
For our 400 hp application, we were not concerned with finding a four-bolt main 350 block. The two-bolt blocks are much more prevalent and more than stout enough for our 6,000 rpm (hydraulic roller) small-block. Having previously run 540 hp and 7,000 rpm on a two-bolt block, we were not concerned about using one here.
The wrecking yard actually offered us a warranty (for an extra $12) that allowed us to return the motor for a replacement if it was internally damaged and unusable. As it turned out, the warranty money would have been wasted since our motor turned out to be a healthy customer. If offered, the warranty is still cheap insurance. Sure, you'd have to pull another motor, but you wouldn't be out the $200 if you found a spun bearing or some other malady that might keep you from using it immediately.
The final test was to check oil pressure. A new oil pump was not on the budget and we were hoping to get by with the stock pump. After filling the pan with Lucas synthetic 10W-40 and spinning the oil-pump driveshaft with an electric drill, we were rewarded with nearly 60 psi of cold oil pressure. We were in business.
Our TPI 350 was originally rated somewhere between 225 hp and 245 hp (depending on year). To reach our goal of 400 hp, we needed to address the fundamental restrictions to power production. First on the list was a set of cylinder heads. Initially we considered simply upgrading the existing heads with hand porting, milling and a valve job, but soon dismissed this idea after adding up the cost of all the proposed modifications to the stock heads. We were looking at a machining bill of near $350 to rework the stock heads.