Re: [AMC-list] hydraulic vs solid cams

[Frank Swygert <farna@xxxxxxx>]

I just looked in the 63 TSM. The cam specs are the same -- 244° duration on both, opening/closing events the same. Lift is different, so the cams aren't identical. For the iron block engine (solid lifters), lift on the lobe is 0.262 intake, 0.263 exhaust. For the aluminum engine (hydraulic lifters) lift on the lobe is 0.254 for both (plus or minus 0.006). 

Since the cam profile is the same, you can have a solid lifter cam reground to the hydraulic cam lift. Or you should be able to use it as is and have a higher lift cam. When my solid lifter cam was reground Lunati added 20° duration and 0.10 lift (total -- total lift is lobe x rocker ratio, which is 1.4:1 -- later AMC sixes use 1.5:1). 

Since lobe lift is 0.262, 0.262 x 1.4 = 0.370" total lift stock for the solid lifter cam. Lunati reground my cam with a 0.334" lobe lift to achieve 0.470" lift.

I think we can assume that the lifters will pump up and make the 0.010" shorter hydraulic cam about the same lift (maybe slightly more or less) as the solid lifter cam. 0.010" additional lift on the cam lobe only makes 0.015" more lift on the cam. I think it's safe to say that won't make a noticeable difference. 

The real thing to look at now is the cam bearings -- are they the same? Bearing diameter specs aren't in the TSM. The parts book lists only two different cam bearing sets for the 196 (all three). There was a change sometime in 1961, early engines used one set, all made after roughly mid 1961 used the other set through 65. So the AL and Fe engines used the same cam bearings, and the cams will interchange as long as you don't mind 0.015-0.020" more lift. Distributors are in the same place and is the same model on both too, so the dizzy drive gear is the same. I'd say that cam Tom has would work just as well, just make sure the little extra lift isn't going to be too much. I don't think the cam Tom has gave a total lift of 0.470. As long as you're under that it should be fine. I don't know if the engine will take anything more than 0.470" or not, but I know most won't take over 0.500" without work or different valve springs, and sometimes retainers. Stock springs usually start to bind over 0.500" lift. 

---------
Date: 25 Feb 2010 06:20:31 -0000
From: das24rules@xxxxxxxxx

so, who knows the difference in the cam specs of the hydraulic and solid
lifter cams for the 196? 
i have a couple of good solid lifter cams. i have a couple of froze hydraulic
lifters in my aluminum motor. i cant tell if the cam is pitted or not. i
wonder if where tom got his rv cam makes one for the aluminum motor with the
same kind of increases?? i dont have the program for my computer to compare
the cam specs. i dont even know what the original cams are. the tsm said
something like .254 or so lift? thats all i saw. i think it could probably
stand alot more work for more bottom end torque. that would be nice. so, ya,
im just wondering (pretty sure i am) out of luck to use a good cam from my
solid lifter cast iron motor.  

--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
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http://farna.home.att.net/AMC.html
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