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Hey fellas I'm rebuilding a 1970 429 with dove c heads and factory flat tops with small valve recesses. Currently I am wondering about the dynamic compression with the factory cam before I go in over my head with parts that won't play nice together. Just looking to build a nice cruiser motor with some spice for a 5000lb mkIV lincoln.
I have plots of 2 different factory 460 cams(no early 429 cams) and neither one is similar to what this chart shows. I also have a plot of a stock 429 CJ cam. I wonder how many cams were really used in these engines and I wonder what tappet height was used to generate the durations and events used in this chart.
I have plots of 2 different factory 460 cams(no early 429 cams) and neither one is similar to what this chart shows. I also have a plot of a stock 429 CJ cam. I wonder how many cams were really used in these engines and I wonder what tappet height was used to generate the durations and events used in this chart.
Good point.
Bottom line, you really need to confirm camshaft specs with a degree wheel when you build the engine. You can confirm the intake center line, camshaft advance, piston to valve clearance, and find the intake valve closing angle. The intake valve closing angle is the piece of the puzzle needed in order to calculate dynamic compression ratio. If you look at those DCR calculators, you'll see you can enter the camshaft's intake duration, or you can enter the intake valve closing angle (IVC). The IVC method is the most accurate.
Using .100 tappet lift I can't get those numbers to jive with the cam that I've got plotted.
@ .100 it has the intake opening 25.5 degrees after TDC, closing at 5.2 after BDC.
Ex Opens 25.7 before BDC, closes 34.5 degrees before TDC.
Intake duration @ .006 is 256, exhaust 265 @ .100 duration is 160 intake and 171 exhaust
Overlap is 31.5 degrees @ .006 and non existent @ .100 by 60 degrees.
These events are important because while I have a good accurate plot of the factory 460 cam I don't know exactly where the factory had it installed in the engine. In my plot I chose a 105 ICL but that's probably way more advanced than what the factory used with the 112 LSA.
