Inliners International Forums General Discussion Engines Langdon's 292 Marine Cam?

The camshaft specifications for the two different "Marine" versus "H.O. Marine" are quite different. For full details of the Langdon "292 H.O. Marine" camshaft, you really need to speak with Tom Langdon, or someone that has run his camshaft. He does not give the 0.050" duration, which is much more meaningful than total duration specifications. OEM manufacturers camshafts usually have much slower loading ramps and lower lobe profile accelerations to minimize wear, extend camshaft and lifter life. Total maximum total lift is also usually lower to reduce valve spring fatigue. The OEM engines must run multi 100,000's of miles with next to zero failures.


Chevrolet/Mercrusier 250 "Marine" ...288/288 total duration, 0.403/0.403 total lift, 192/192 0.050 duration, 112 lobe seperation
Langdon "292 H.O. Marine"..............262/262 total duration, 0.442/0.442 total lift

Aftermarket camshaft manufacturers usually run much more aggressive ramps rates so the 250 Marine (OEM style) total duration of 288 degrees cannot be directly compared with the Langdon 292 H.O. Marine total duration of 262 degrees. As a relative comparison, the Comp Cams 260H cam lists a 260/260 total duration, 0.489 total lift, and a 212/212 0.050 duration.

Tom Langdon, having spent his long GM career testing inline GM engines, balances performance and long term reliability. As a note, he limits his valve lift to 0.442" to meet long term fatigue stress limits on the stock valve springs.