Reply to "Please help a beginner ☺ with Valve Spring Questions"

Hi Peter

The most recent cam you've mentioned is a Crane Cams camshaft, a fairly old grind, from the days when Harvey Crane was still around and they ground good cams ... about 1980s or possibly earlier. In fact I remember camshafts with these lobe centerlines from the 1960s ... and I've used them myself for recent cams. The lobe lift is not up to modern standards due to the age of the grind.

The notable characteristics include low overlap and placement of the overlap event fairly well within the dwell period, both will promote good low rpm power. The intake valve closes early enough to avoid reversion and to set the dynamic compression properly, but not too early. All of these things will work well with the Weber carbs, and help avoid a fuel plume and tuning headaches. The exhaust valve opens early enough to promote high rpm power and over-rev with a wide range of exhaust systems. I think the camshaft would work well with your Webber carbureted engine, as long as you can accept the limitations of the lobe lift. On the positive side, the lobe lift is gentle enough to work very well with the factory rocker arms.

The camshaft's advertised duration is based upon lift at 0.004, rather than the industry standard of lift at 0.006, so I've had to make an educated estimate regarding advertised duration at 0.006, and valve events. Here's the specs based upon my estimate:

282°/286° duration @ 0.006 (advertised)
109°/119° lobe centerlines
230°/234° duration @ 0.050
52° Hydraulic Intensity
56° overlap
114° LSA

EVO = 82° BBDC
IVO = 32° BTDC
EVC = 24° ATDC
IVC = 70° ABDC

Lobe lift = 0.3101/0.3150
Theoretical lift (advertised)= 0.536/0.545
Net lift = 0.528/0.536