Old post but my experience of this initially was in 1983 when I had a 1970 Dodge Charger R/T w/440 Magnum and IIRC the factory intakes were single groove and exhausts were 3 groove that butted. I read in the old Mopar Performance book about grinding the ends of the locks “if” they butted together. Only enough so that they didn’t butt. The theory was that they grab the valve tighter. I recall using the Isky single locks on the intakes, and doing as the book mentioned on the oem exhaust locks. Was it necessary? Not likely but it was a shoestring budget mod and I was using that book as my guide on building a so called performance engine. Great book by the way, was the Bible for me in my early days of messing with engines. Also, “Moper” replied “x2 very old trick” ....yes, 38 years ago =old!:eek:
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