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Duke,
Since you you have talked about both, is this "new" cam a roller or standard hydraulic lifter design.
Thanks,
Tom
Since you you have talked about both, is this "new" cam a roller or standard hydraulic lifter design.
Thanks,
Tom
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Re: '62 engines
It's a hydraulic flat tappet design- stictly bolt-in, but the custom grinding will cost about double a typical catalog design. It uses two OE lobes, but the inlet and exhaust lobes are from different OE cams. It has very different POMLs and LSA from typical vintage cams, but is very similar to modern SB cams when exhaust/inlet port flow ratio is factored into the equation.
Right now it looks like Crane is the best source since they offer clones of both of the OE cams that have my lobes of choice, so they have suitable lobe masters and have told me that they can grind the cam with my specified POMLs and LSA.
As I've said before this cam is specifically engineered for vintage heads that are POCKET PORTED to typical instructions that have been widely available for over 30 years, and because the useable rev range will likely extend to the valvetrain limiting speed, a connecting rod upgrade is mandatory for pre-'66 engines with the weak first design rods. The '66-up second design are "just okay" at this rev level (up to 6500)if they pass Magnaflux, so I strongly recommend an upgrade for the second design rods, too.
The recommended CR for this configuration up is a true 10-10.5:1, which can be accomodated in most cases with the Keith Black KB157 hypereutectic cast pistons. These have a slight dome on them and depending on final deck clearance, suitable gasket thickness should provide the desired CR range. Since the KB pistons are designed for tight clearance like the OE pistons, there will be no "piston slap" noise that might give away the fact that the engine is "modified", and since effective overlap is maintained at the level of the base engine cam, it will idle just like an OE base engine. My expectation is that is will pass a PV as an unmodified base engine.
Since this cam has a very late closing inlet valve, the DCR is modest, and it can take high compression on current premium fuel, and high compression is necessary to gain the most benefit from the design. Low end torque will be less than the 327/300, but more than an OE L-79, and top end power should be well in excess of an OE L-79 and somewhat in excess of a L-79 with pocket ported heads and the same CR - the best of both worlds.
If one wants to extend the useable power bandwith to over 6500 the LT-1 mechanical lifter cam is still the way to go since with the same head modifications and compression it will make useable power to 7000+ and the valvetrain limiting speed with the OE 068 spring is about 7200. Of course, in this configuration, a rod upgrade for any small bearing 327 is absolutely necessary unless you want to someday look at a rod hole in your OE block. No if, ands, or buts!
Duke -
Re: '62 engines
Duke,
I would assume then that this configuration will work well with 2 1/2 inch ram horn exhaust manifolds? Sounds good.
BruceComment
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Re: '62 engines
Yes, the 2.5" manifolds are best as is the 2.5" C2 exhaust system. (The cam is specifically designed for the OE exhaust manifolds. Headers would be of little value.) If fact this is probably one of the best OE exhaust systems ever installed on a production car even including the modern era. It probably doesn't generate more than about 3 psi backpressure on a massaged SHP small block at 7000 revs, but it is somewhat restrictive for the exhaust flow rate of big blocks - up to about 5.5 psi backpressure on a massaged L-72.
Note that backpressure increases with the SQUARE of flow rate, so about a 40 percent increase in exhaust flow rate DOUBLES backpressure!
The 2.0" C1 piping (even with 2.5" manifolds) will reduce peak power output somewhat as will the 2.0" manifolds on a C2 even with 2.5" pipes. (Of the two, the C1 configuration is probably the most restrictive.) I can't quantify the magnitudes, and it's probably not major, but would be measureable if examples of each exhaust system configuration with identical engine configurations were tested.
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