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Blown5k wrote:Yeah tell that to most of the racing teams in the world that use the stuff im sure there engines are`nt "highly stressed"
Redmist wrote:I don't like reduced base circle cams. They alter (read f**k up ) your valve train geometry. You end up wearing the engine much quicker and have problems with a linea lift.
Redmist wrote:Again I'm against reground cams in a modern engine. Your right about the bucket being more exposed because of the reduced base circle. You can just imagine the stresses on the bucket when the lobe strikes it!
Your also increasing the weight of your drivetrain by adding bigger shims or increasing the length of your valves.
Because the 4AG has a cam lobe on either side of a cam bearing journal, it makes it critical that adequate clearance is given between the lifter (bucket) & shim and the bearing journal surface. The reduction of the cam lobe base circle, without extensive head modifications, requires the use of thicker shims. This will increase valve train reciprocating mass and inertia (adding stress and increasing the potential for major failure). Too thick a shim necessitates radiusing the edge to clear the cam bearing journal, increasing the possibility that the cam lobe will grab the shim and flip it out. An alternative would be to narrow the cam shaft bearing, but this would cause greater wear on the bearing caps and/or increase oil loss (lower oil pressure). Another alternative would be to reduce the bearing journal diameter, but that would require welding up the bearing caps and reboring them
Therefore it is strongly urged that reground cams (Bull Frog, PAECO, etc.) not be used. Use only cams ground from new billet stock, e.g., HKS, TRD, TODA POWER, TOYOTA, etc. My suggestion is that if TRD, i.e., Formula Atlantic engine supplier, or one of the others that have extensive 4A-G racing experience do not do it, then you should be really skeptical that someone else would or does anything different. Regrinding a camshaft only removes material that the 4A-G needs to maintain the base circle the same size as the bearing journal.
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