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Roller Bearings
Is anyone using roller bearings in the block for the camshaft in lieu of regular cam bearings. What are your thoughts and experiences with them?
Rick |
$0.02,
Have heard of using roller camshaft bearings to reduce friction. From what I've seen, and read, "not bad, but not great". Valvetrain friction comes from the lifters on the cam, and the rocker arms on the fulcrum ball. Work on these two, and you can free up 50 FPTQ at the flywheel. Use roller lifters (OEM's have gotten into this) and roller rocker arms, and your 351W now thinks it's a 400. |
Yes, in my aluminum race engine. It is unlikely that you would gain any benefit from roller cam bearings on the street. They will however, lower the oil demand in a race engine that turns 8-9000 rpm by 3gal./min since they don't require direct oiling. They also have a larger cam journal diameter and that will allows the base circle to be larger on those .700-.800 lift cams. As mentioned friction reduction is another gain.
Scott |
Scott,
I was under the impression that the cam journals were the same diameter as stock, i.e. any "regular" cam will fit in with the roller bearings. I realize that the block has to be mechined out to accept the roller bearing, but I didn't think the "end result" was any different size than stock journals. If what your saying is true, after doing the roller bearing installation, you'll have to find a custom ground cam to fit in the block, no? - Jim - |
Jim,
The standard spec for the 351W is stepped journals - for ease of installation. 1. = 2.080 2. = 2.065 3. = 2.050 4. = 2.035 5. = 2.020 the "C" roller bearing is 2.051 all thru and offers no advantage with regard to base circle size. the "D" roller bearing is 1-4: 55mm (2.165) and 5: 1.968. Jack Roush developed this size to increase base circle diameter and run bigger lobes. You wouldn't want to run a standard cast cam on roller bearings in any case. A billet or special hardened cam should be run. Comp Cams has done the most developement and has all the durability issues worked out. Scott |
Scott,
Thanks for the better discription of how it works!! This place is so neat..... learn something new everyday. - Jim - |
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