Expert: Dan Liddy - 2/22/2004

Question
Thanks Dan for answering my question.Are the differences in the camshafts to do with the shape of the cam lobes.I Have a 68 impala with hydraulic lifters does that mean i have a hydraulic camshaft or can you mix and match.And would you have to have a hydraulic roller camshaft for hydraulic roller lifters.Thanks for your patience with these querys.

Answer
Hi again:

Yes the differences are in the profiles of the cam lobes. You can measure the lift with a micrometer, or vernier caliper. The duration must be measured either with a computerized "cam doctor"  or with a dial indicator, a degree wheel, and LOTS of patience.  

I believe you would have to use a cam intended to be used with hydraulic lifters, and you MUST change them when changing the cam. To try and re-use the old ones is foolish, and will probably ruin the new cam in short order.

I'm not sure that there is such a thing as a hydraulic AND roller cam at the same time. Roller lifters take the place of the hydraulic ones, and require that you properly adjust the valves periodically. You should probably also add a threaded stud kit to your parts purchase, the normal rocker studs are pressed into the head, and sometimes wiggle out when more serious cams are used.

Your '68 Impala came with either a 285 cu in. V-8, or perhaps a 348- - -If it's the original 285, you'll gain a lot more by switching to a 350 small block, and leaving the innerds alone.  Change the rings and bearings before installing it.

Again, good luck

Dan Liddy