The Original Junior
Posted 02 August 2008 - 01:14 PM
Posted 03 August 2008 - 12:40 AM
Posted 03 August 2008 - 01:50 PM
Posted 05 August 2008 - 04:45 AM
Posted 05 August 2008 - 05:58 AM
It makes me a nervous wreck seeing that car on it's side on a sand or cement block for the chassis shot.
Edited by promodmerc, 05 August 2008 - 06:01 AM.
Posted 05 August 2008 - 06:25 AM
Hey Zeb, I think we've had the "Porkupine" conversation before, haven't we?
Posted 05 August 2008 - 07:08 AM
Posted 10 August 2008 - 06:36 PM
Posted 19 August 2008 - 03:57 PM
Edited by locoengr, 19 August 2008 - 03:59 PM.
Posted 28 September 2008 - 06:36 AM
Here's a brief example from a "How Stuff Works" website I have.
Early in 1963, a mysterious new Chevrolet 427 V-8 appeared at Daytona International Speedway. After being shocked by its acceleration and speed, rivals who were able to look at it with the rocker covers off noticed its odd valve angles, and nicknamed it the "Porcupine" engine. In the 500-mile race, the Chevy simply sped away, leaving all other cars behind, and lapped at average speeds up to 166 mph before dropping out-due to unspecified engine failure. Shortly after that, GM's top management put a ban on racing activities by its car divisions, and no more was heard of the "Porcupine." However, development work on it continued unabated at the GM Technical Center in Warren, Michigan. It resurfaced in the spring of 1965 as a high-performance option for the Chevelle, the full-size Chevrolet, and the Corvette, with capacity to cut 396 cid.
Intake valves were set at an angle of 26 degrees to the cylinder axis, and exhaust valves were tilted 17 degrees from the same axis. That wasn't all, for both intake and exhaust valve stems were also tilted in side view, one forwards and the other backwards, by 9 degrees. This lined them up with the pushrods to avoid setting up any rotation in the rocker arms. This basic cylinder-head configuration was then tested, fiddled with, honed, and polished until it provided optimal breathing. That part of the design was then frozen, and all other components were designed around it.
The 396 V-8 was just one member of a whole "Porcupine" family, officially titled Mark IV and marketed as the "Turbo-Jet." There were four in all: two high-performance car engines of 396 and 427-cid, a 366-cid heavy-duty truck unit, and a 427 heavy-duty marine version. The 396 was scheduled to replace the 409 in all its applications, even though that engine was hardly old. Why was it scrapped after barely five years' production? Aside from its basic design limitations, the type W had been tooled for relatively low production volume. To meet future demands, Chevy's Tonawanda, New York, plant (near Niagara) would have to be retooled anyway. Semon E. "Bunkie" Knudsen, then division general manager, decided that only the most modern engine could justify such a major tooling reinvestment, so the "Porcupine" got the nod.
There was no thought of any carryover from the type W or 409 to the Mark IV. An all-new block with 4.84-inch spacing between bore centers was chosen, giving a bore of 4.094 inches. Stroke as 3.76 inches.
The 409 had a deck angled at 33 degrees from horizontal to allow a wedge-shaped combustion chamber to be created with flat-faced heads. By contrast the Mark IV block had the usual deck angle of 45 degrees to the cylinder axis. Main bearings were 2.75 inches in diameter, a quarter-inch larger than the type W. Main-bearing width was also increased, adding two full inches to the cap-clamping surface. The forged-steel crankshaft was cross-drilled to deliver oil to the rod bearings through a full 360 degrees of rotation (a feature the W lacked), and crankpin journals were kept at 2.20-inch diameter.
So basically Slim, this whole engine series are called Porkypines.....but it usually is reserved for the 1st engine that showed up at Daytona Speedway in 1963.
Edited by zebm1, 28 September 2008 - 06:36 AM.