My experience with Jones mechanical lifter camshaft was that the engine would pull cleanly to 6600 rpm, and crash. It was supposedly designed to pull to 7200 rpm for the EMC competition build. I had 1.94/1.56 light weight 5/16" valve stems, titanium retainers, LS beehive springs, Smith Brother's chromoly push rods, Trend Lifters, and Harland Sharp 1.6 roller rocker shaft mounted rocker arms. I had three sets of heads ported, with all the light weight parts mentioned for each of them, and we tested 5 different sets of valve springs all with the same results that the engine would "pop" at 6600 rpm and nose dive. I upped the seat pressure from 135# to 167# keeping the over the nose at a safe pressure of 430#. After upping the seat pressure to 167#, the engine would pull to 6900 rpm and crash. We entered the engine in that configuration and was able to make three successful pulls to 7100 rpm with the "pop" and roll over on the top end. After the EMC, back at the shop, we installed a new Isky camshaft that was ordered but did not make it in time for dyno testing before the competition, and the engine responded with clean pulls to 7400 rpm without a single "pop" and picked up 12 horsepower. Everything was just exactly as it was for the EMC except the camshaft. Same Trend Lifters, everything. We(Ted Eaton and I) did a degree wheel check of every lobe on the Jones camshaft and if you advanced or retarded it any from straight up, the lobes were all over the place with none of them falling into line with the cam card. #1 was only correct at straight up, all the other cylinders were off as much as 8*+/-.
When I questioned Mike about the results, he asked me a bunch of questions about the build, and then the lifter angle for the Y. He ASSUMED the camshaft lobes were the same as the SBC, and they are not. There is 3* difference between the lifter bore angles in the Y from the SBC. He corrected his information, cut me two new camshafts, and I am going to test one of them in the next few days. When I degreed it, I went ahead and checked #6 against #1, and it was spot on, correct. We shall see. Joe-JDC