Every rod and main bearing journal was mic'd for size then micro-polished. The oil passage
I personally shot-peened a replacement set of connecting rods I bought and balanced decades ago (the original rods and crankshaft were beyond repair) as well as the 461-X heads in the VHS high-pressure blasting tank. This process removed all foreign matter and also, according to VHS, made the rods stronger. My replacement crankshaft was bent 0.003-inch so VHS' Alex Pulido straightened it in the VHS crank jig (VHS is a full service engine facility). Chevy crankshafts usually check out OK in the balance department. Ours measured 12 grams out-of-balance. Remembering that 22 grams equals one ounce, the crank was just over one-half ounce out-of-balance. Both Alex Pulido and Joe Sherman said this was OK for a stock engine, but not acceptable for a high-performance engine. Alex reduced the out-of-balance number down to a mere 1/2-gram. That equates to 1/44th of an ounce. Looking good.
The heads needed a total rebuild, including deck milling (0.010-inch), hardened exhaust valve seats, new stainless steel 1.94 and 1.50-inch valves, bronze wall valve guides and the aforementioned combustion chamber crack repair.
When Alex Pulido checked the crankshaft balance, the dials told him the 12 grams of extra
Larry Ofria called his crack repair process "drill, tap and pin." The crack was first drilled completely out. It took four 3/16-inch, side-by-side holes to eliminate it. Each hole was then pipe-tapped with a tapered metal tap. They were also dipped in a type of space-age glue and installed one at a time. Each tap was screwed firmly into place then was sawed off flush with the deck. The tops of the taps were then finish-ground flush. Ofria said "drill, tap and pin" is a very effective and ever-lasting head crack remedy.
Joe Sherman Racing Engines won the 2002 Engine Masters Challenge hosted by our sister publication, Popular Hot Rodding. Sherman graciously agreed to help me with short-block assembly and camshaft degreeing. He also said he'd dyno-test it, too. Sherman is a consummate master of the little things that make a performance difference. He had not seen an early 327 in ages. There's not much difference per se, but he was impressed with the bigger port, 1962-63 fuel-injection 461-X heads. Their intake ports have higher floors and roofs and the overall flow volume is greater than a regular 461 head. They were conceived for more high-rpm horsepower in competition SCCA road racing, fuel-injected Corvettes. Although they were legal over the years on NHRA Stock Eliminator Chevys using 461 heads, they have all but dried up today. A set (condition unknown) recently sold on eBay for over $1,200.
Sherman flowed one 461-X head and remarked that its flow volume was similar to a late-model Vortec iron head. That's good, as Vortec heads give an average 350 about 40 extra horsepower, says Sherman. We knew all along that we had no equipment or funds to clean up the ports' short side radiuses and various port bumps and lumps. Sherman said he'd help us with some very minor under-the-valve backside grinder massaging. He thought it would be worth an additional 20 more cfm and 20 additional free horsepower. We know our Chevy engines, but pale by comparison to Sherman's genius. He's been at it for 40-something years.
Here is one of the heads fully machined with hardened exhaust valve seats ready for the ne
Rochester F.I. Or Carburetor Induction?Very few readers own or know anything about early Corvette Rochester mechanical, constant-flow fuel injection. So, for the sake of a more meaningful story, Sherman recommended I use an induction setup most all of you know about and can easily relate to, an Edelbrock Performer RPM intake manifold and an Edelbrock 750-cfm carburetor.
The Rochester fuel injection system flows about 650 cfm and has port nozzles. The Edelbrock system has nearly the same runner flow so we don't think one should out-power the other by much. Fear not fuelie lovers, as we may do something with this unit further down the road to see how it has held up over time.
Next up: Engine assembly, cam degreeing, plus a dyno test on Joe Sherman Racing Engine's Super Flow dyno. We're hoping for a nice running Vette on pump gas with 370-380 hp. Sherman thinks we'll see 400 from our '62 10.0:1 331 small-block cid. Stay tuned.
|461-X HEAD CFM FLOW COMPARISON|
|INTAKE PORTS||EXHAUST PORTS|
|Stock||Valve Lift||Shermanized||Stock||Valve Lift||Shermanized|
To repair the small crack, it is first drilled out, one hole overlapping the next. Valley
Once each hole was filled with a threaded metal tap, it was sawed off then milled down fla
This photo shows three things: The repaired head crack, new bronze wall valve guides and n