The Engle W120 is a Hot Street VW Beetle camshaft grind is designed for 1.1 or 1.25 rockers, and it's specs are .397" Cam Lift, .435" Valve Lift (1.1 Rockers), 294 degrees of advertised duration, and 253 degrees of duration at .050", on a 108 Lobe Center.
With more duration and slightly more lift than it's little brother the W110, this cam is designed to give more power at the top end while sacrificing low end. You can not use this with a stock carburettor,
You really need dual 40mm EMPI HPMX or Weber Carburetors for this cam to behave at idle and under 1500 RPM.
This cam really needs some port work and/or larger displacement to work properly. Expect a powerband of 1500-5500 RPMs, the more headwork and carburetion the better the low end will be.
Dual springs are required with 1.1s or 1.25 rockers. Use a compression ratio of 8.75-9.5:1.