Correct Cam
I am purchasing a cam for 427/425 and have been referred, on earlier posts, to the FM cam Part No. KC 165R. The cam spec on this cam are .520 lift on intake aqnd exhaust. My 1966 service manual specs the lift on the OE cam at .3057 lift I/E. Why the difference. I feel the FM cam advised is the correct replacement but my service manual has for the most part been a reliable source.
-
-
Re: Correct Cam
Walter,
Can you post a picture of the page from your service manual? There's something wrong here. Everything I've read on the cam says the lift is around 0.5 inches intake and exhaust. Check out the attached sheet. I'm not sure where I got it, probably here. You're interested in the 3863143 cam.
Joe -
Re: Correct Cam
Walter,
Here's another clue we're steering you in the right direction. If you go to NAPAonline, click "Search NAPA Catalog," punch in 3863143, select "Interchange", then hit the arrow, here's what you get:
http://www.napaonline.com/NOLPPSE/(S...Dn=0&Dk=1&Dp=3
As you know, the SEP CS165R camshaft is part of the KC165R cam and lifter kit.
JoeComment
-
Re: Correct Cam
The .3057" value is gross LOBE LIFT, including the clearance ramp. Valve lift is 1.7 times this minus running clearance, but some specs don't even subtract running clearance - just multiply gross lobe lift times the specified rocker ratio. Actual valve lift, even after subtracting running clearance, is somewhat less because the 1.7:1 rocker ratio is theoretical. Actual RR varies with lift - starts out at less than 1.7 and almost reaches 1.7 at max lobe lift.
This cam uses the same lobe on both sides (and the same lobe with a slightly smaller base circle was used on the inlet side of the LT-1 cam), but GM recommended different clearances - .020" inlet and .024 exhaust in 1965, but changed the spec to .024/.028 in '66. I recommend setting the cold valve clearances to the 1965 spec.
DukeComment
Comment