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Message: <blockquote data-quote="Silver95bird" data-source="post: 1428965" data-attributes="member: 21743"><a href="http://forums.tccoa.com/7-engine-4-6l-5-4l/99191-ford-4-6l-2v-specifications.html" target="_blank">http://forums.tccoa.com/7-engine-4-6l-5-4l/99191-ford-4-6l-2v-specifications.html</a>I found this, it's rather interesting. Among other things, it lists the rockers as 2.0 ratio. That's odd, as comp's catalog and others list them as 1.8. So, let's dig deeper. It lists cam lift as 7.11mm/7.47mm at the cam, 13.00mm/13.75mm at the valve "theoretical valve lift". But a 2.0 rocker ratio would turn 7.11/7.47mm into 14.22/14.94mm, which converts to .5598/.5881" of lift at the valve! What gives? In both cases, the difference is about .048" between "theoretical" and what the ratio is listed as. Is the collapse of the lash adjuster causing the cam to lose that much lift?Picture the engine layout. The cam/follower would look like a teeter totter. As the cam increases in lift, one (or both) sides has to give. If one gives but not the other, you get exactly a teeter totter. If both the adjuster and the valve move, it's more like a teeter totter with a spring under the pivot in the middle. The give in the adjuster is causing give in the valve motion as well. I'm beginning to suspect shimming the adjusters would be noticeably different in the valve events. I don't think they should be shimmed the full .048, you need slack for production differences and to retain the oil squirting feature of the adjuster. I'd suspect anything up to a .025 or .030 would work though. Don't forget, it's like changing 1.5 rockers to 1.6 rockers on a sbc. It doesn't change just the lift, it also changes the advertised and .050" cam events - even if that's subtly done. I'd suspect mapping the stock cam lobe, and then mapping the same lobe again with a .030" shim would be most interesting. The mapping needs to be done on the valve though.If the Cobra adjusters were collapsing .012 ish on the base circle, and we're losing another .048" in collapse, that's .060" of total collapse in the adjusters. That's a lot!Now imagine different shims under intakes and exhausts. You could tailor any cam to anything you'd want that way. Neat, huh?</blockquote>