differenza tra big e small block

[mopar]

I 348 erano montati sulle Impala e full size dal 58 al 63 circa, e poi il 409 ne ha preso il posto. Ultimo anno di produzione il 1965, quando venne sostituito dal 396 porcospino.

[Nuvolari]

[quote name='mopar' post='350876' date='1/5/2011, 17:49']quando venne sostituito dal 396 porcospino.[/quote]





non dirmi che questo motore assomiglia al

??

[Wildcat]

[quote name='mopar' post='350863' date='1/5/2011, 16:42']Il 348/409 non fanno parte di queste due famiglie di motori, ma sono a se stanti, e vengono definiti W series, per la forma dei coperchi punterie.[/quote]



si quello lo sapevo, li ho inseriti anche per far sapere che esistevano anche quei 2 motori oltre ai pi? conosciuti derivati di 265 e 396...ma quindi dici che non c'entrano una pippa con le altre 2 famiglie? il 427 e 396 non avevano proprio nulla in comune con il 409?

[mopar]

solo la flangia di attacco al cambio. Per il resto non c'? niente di intercambiabile

[mopar]

Development of the second generation big-block started with the so-called Mystery Motor (Mark II Z33 427) used in Chevrolet's 1963 Daytona 500 record-setting stock cars. This "secret" engine was a substantially modified form of the "W" engine, and was subsequently released for production use in mid-1965 as the Mark IV, referred to in sales literature as the "Turbo-Jet V8."



Where the Mark IV differed from the "W" engine was in the placement of the valves and the shape of the combustion chambers. Gone was the chamber-in-block design of the "W" (which caused the power curve to drastically sag above 6500 RPM), and in its place was a more conventional wedge chamber in the cylinder head, which was now attached to a conventional 90 degree deck. The valves continued to use the displaced arrangement of the "W" engine, but were also inclined so that they would open away from the combustion chamber and cylinder walls, a design feature made possible by Chevrolet's stud mounted rocker arms. This alteration in valve placement resulted in a significant improvement in volumetric efficiency at high RPM and a substantial increase in power output at racing speeds. Owing to the appearance of the compound angularity of the valves, the automotive press dubbed the engine the "porcupine" design.



As part of the head redesign, the spark plugs were relocated so that they entered the combustion chamber at an angle relative the cylinder centerline, rather than the straight in relationship of the "W" engine. This too helped high RPM performance. Due to the new spark plug angle, the clearance provided by the distinctive scalloped valve covers of the "W" model was no longer needed, and wide, rectangular covers were used

[ronald66]

IL 409

Che motore ragazzi