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TDSRacing Feb 13th, 06, 6:43 PM I am building a 454 motor I perchase for my Chevelle and am going to 496......but this frees up some of my old parts for a boat project. Sorry if this is OT but with run of the mill flat top pistons what ballpark CR would 049 or 781 heads have? Tim Johnny O Feb 13th, 06, 9:16 PM Assuming the chambers are standard size, around 120 cc, you'll be lucky to get 8.25/1 using flat tops in a 496. Johnny O Feb 13th, 06, 9:20 PM Just ran it thru calculator...using .050 gasket, 4.50 gasket bore, and .020 deck, it says 8.21/1..... pdq67 Feb 13th, 06, 11:02 PM 496.. 118 cc head, .020" shim headgasket, .025" down in the hole and -6 cc true flat-tops = about 8.54! You will need an about 3/16" domed open chambered piston to get up to 9.8 b/c that's what my 496 is. I just called up ROSS and told them what parts I had and that I was using stock 454 spec's for my 496 and that I wanted a 9.5 to 1 motor. Later, I changed from .039" composites to .020" steel shims and am now at about 9.8... pdq67 PS., New Merlin cast-iron oval heads! TDSRacing Feb 16th, 06, 10:36 AM Thanks!!!!!! Great info. TDSRacing Mar 16th, 06, 11:20 AM I hear the 781 are better heads. I may just stay 454 and spend $ elasewhere. The 'ol Vert needs a lot of parts. MAn that CR numbers are low ones. HMMMM makes me think. Tim 427L88 Mar 16th, 06, 4:05 PM Ya too low. HUFF IT! :) | ||