I am rebuilding my 67 427 (400hp) I plan to use stock rocker arms, push rods, etc, (I know there are better setups out there) but would not mind updating the camshaft. Would like the car to idle as it originally did, but would not mind better performance. Am looking for a suggestion on what camshaft to use with the stock style parts I am installing, without being able to tell at idle I have modified the performance.
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Re: 67 427 camshaft choice
Rob-----
My recommendation is simple and consistent: use a retrofit hydraulic roller camshaft and kit available from Federal Mogul/Speed-Pro, Crane, CompCams, or Crower. For your application, I'd use one with about 275-280 degrees advertised intake duration. You can go up to about 285 degrees for increased performance, but the idle quality might be a bit rougher than your original L-36/L-68 camshaft.
You will be able to use all other stock valve-train components EXCEPT pushrods. Most of the retrofit hydraulic roller cam kits are supplied with the required special-length pushrods but the pushrods have ball-type, welded tips which are unlike original pushrods. However, if you want to maintain stock appearance for the pushrods, you can have custom length push rods made with the stock tip style. Both Crane and CompCams will provide such pushrods on special order.
When using a retrofit hydraulic roller camshaft you will also need to braze in a thrust plate on the inner surface of your timing cover and install the thrust button provided with the camshaft kit. I also strongly recommend the use of a Cloyes Timing Gear set with needle bearing thrust plate on the camshaft gear. None of these are visible when the engine is assembled.
In my opinion, a hydraulic roller camshaft is "where it's at" for street performance applications in today's world. Virtually all modern, PRODUCTION V-6 and V-8 pushrod-type engines use them. They provide the best of all worlds for STREET performance.In Appreciation of John Hinckley -
Re: 67 427 camshaft choice
A hydraulic roller allows more aggressive acceleration to open the valves more quickly, which yields more area under the lift-crank angle diagram, and this will yield a fatter torque curve.
The primary valve timing parameter that affects idle quality is valve overlap. Therefore you want to maintain the same lobe center angle or even increase it a degree or two, as the hydraulic roller with the same LCA will yield more EFFECTIVE overlap because of the quicker valve action.
IMO many aftermarket cams have too much overlap. Overlap is effective when combined with headers, but can really hurt low end torque with manifolds.
As an example of modern camshaft design, the current LS6 cam has a LCA of 117.5 degrees - very little effective overlap and the inlet valve is phased very late
with an inlet centerline of about 115 degrees. Low overlap is critical to achieve good idle quality and emissions. By the same token installing headers on a LS6 does not result in dramatic improvements because the wave dynamics generated by the headers only have a useful affect over a very narrow rev range.
DukeComment
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Joe; small-block, thrust plate follow-up question
Joe,
In your response to Rob, you say: "When using a retrofit hydraulic roller camshaft you will also need to braze in a thrust plate on the inner surface of your timing cover and install the thrust button provided with the camshaft kit."
Do you know if the stock small block L-79 timing cover is robust enough to have the thrust plate brazed on the inner surface as you descibe above for the BB situation? Or does one really need to switch to a beefier (e.g.,. cast aluminum) aftermarket timing cover to handle the thrust loads?
GaryComment
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Re: Joe; small-block, thrust plate follow-up quest
Gary-----
A thrust plate can easily be attached by brazing to a small block cover. For pre-75 covers with the "3 radial" pattern, a specially configured plate can be fabricated from a piece of steel stock which includes the center and about an inch of each radial. The steel stock should be thick enough to be just a tad thicker than the radial "indentions".In Appreciation of John HinckleyComment
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Thanks Joe. *NM*
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Re: 67 427 camshaft choice
Joe......I decided to install stock push rods and rocker arms. That being the case, does your camshaft recommendation change, and if so, which would you then recommend?Comment
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Re: 67 427 camshaft choice
Rob-----
You can use the hydraulic roller with stock rocker arms. However, if you want to go with stock pushrods, then you can't use an hydraulic roller. The custom length pushrods that I mentioned will look exactly like stock push rods except for length. No one would be the wiser since the length of the pushrods cannot be discerned when installed in the engine.
If you wish to use exactly stock pushrods, then I'd have to say that a dual pattern, flat tappet hydraulic cam would be the best way to go. I'd still stay in the 275 to 285 degree "advertised intake duration" range. All of the manufacturers that I previously mentioned will have cams available in this range. These modern cams will produce significantly higher power levels than the original cam and idle will be about the same.In Appreciation of John HinckleyComment
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