I was wondering if there is any difference between the Crane 139021's and the 168741's. I recall reading something regarding this some time back however don't remember what the dif was if any.
Thanks for your help.
John

The 139021 has 296 and 304 deg Duration while the 168741 has 298 and 206 deg duration, both suit hyd roller but the 021 is fo the 1965-96 BB-Chevy 396-454, whereas the 741 cam is for the '96+ BBC 454 - 502. (apparently)

From what I can figure, the 021 is the retro-fit snout style cam. Though the 396 and 427 still require some machining of the timing cover for oil flow, I would assume that it cannot therefore fit the Gen VI with the stepped snout cam and different cover, so that is what the 741 cam is for.

Hope that answers your question!
John.

Give Bob RMbuilder a call. I went through all this in the spring. He can set you up with a matching setup with usable HP not just on paper. I gained 5 MPH for about $2K in parts, cam, spings, lifters, pushrods, retainers, timing chain & cover.

Thanks for your help.
John