I came across this forum while searching the web for help with a problem I'm having. I've found many great resources here concerning cam lobe profiles and suggested machining techniques, but I my question is more fundamental than this. I'm slightly embarrassed to be asking because it seems like I should be able to think my way around this one, but here it goes. I'm designing a model engine (just for demo purposes and never intended to be run) modeled after the LS1. I chose this for the simple reasons that it is a prolific engine with many dimensions readily available and it's a V8. From all of the info and pictures, I've modeled a scaled and simplified version except for the camshaft. I've made several attempts and it never seems to come out right and I need one of you to point out where I'm going wrong in my thinking. Here it goes... Being a 90 degree V8, there will be an intake event for every 90 degrees of crank rotation. Of course the camshaft rotates at half the speed of the crank, so there are 360 deg of cam for every 720 deg of crank rotation. The firing order of the LS engines is 1,8,7,2,6,5,4,3 and the cylinders are numbered with odd cylinders on the right when facing the front of the engine and a clockwise rotation of the crank. When modeling the lobes, I started with the intake on cylinder 1 as 0 deg. The intake lobe of cylinder 2 is therefore 135 deg of cam "behind" cylinder 1. This pair worked out fine, but goes entirely haywire when I try doing any other cylinders. For instance, cylinder 3 is last in the firing order and is 315 deg of cam "behind" cylinder 1. This does not line up with an intake event on cylinder 3 at 630 deg of crank. The same goes for every other cylinder aside from #2. Here's my chart for the firing order, crank and cam angles. Firing Order: 1 8 7 2 6 5 4 3 Crank Angle: 0 90 180 270 360 450 540 630 Cam Angle: 0 45 90 135 180 225 270 315 I'm not sure what I'm missing. I'm happy to share my models or the entire assembly if it helps (Fusion 360). At this point I'm stuck and have been contemplating buying a stock LS cam off of Craigslist just so that I can pull measurements from it directly. Will someone please point out my mistake? Thanks for the help.