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lukeciffer Jun 13th, 07, 07:33 PM i work at a chevy dealership and i'm trying to get my hands on a 8.1L big block core so i can build a 500+ ci. stroker. has anyone had any experiences with these. i plan on using the bottom end only and throwing my iron eagles on it. i think the oil pan is different than the previous generations of big blocks. has any one else tried using that block, and did it fit with the different oil pan? lukeciffer Jun 13th, 07, 07:40 PM oops. i beleive it is a gen VI bock. Larger Dave Jun 13th, 07, 08:25 PM It is a tall deck Gen VI block and will have problems with any Mark IV head; as they do not even share the same bolt pattern (I don't think they do anyway). The existing heads are not of the same design but are symmetrical. There are very few parts that interchange (harmonic balancer bolt maybe). It is an entirely different engine and would work best as GM designed it with EFI and a computer upgrade (take the same approach as you would with the LS-x engines). Larger Dave lukeciffer Jun 14th, 07, 05:53 PM crap. your absolutely right. checked today and the bolt pattern on the head is different. i guess i'll have to go with another 454. Busted Knuckles Jun 15th, 07, 04:33 AM The 8.1L iS actually a Gen VII engine, upgraded Mark IV's are Gen V and VI. Very few companies make any performance parts for the Gen VIII, pretty much best left alone. pdq67 Jun 15th, 07, 08:05 PM Yes, they have SB, LS- type BB heads on them!! Tall decker at 4.25" b x 4.37" s = 496''er!! The cheapest way to come up w/ a big motor using a stock block is to use a .060" to .090" over, 502 over the counter block and install a 4.375" crank in it!! You come out w/ a 564.1" or a 571.6" engine!! That said, if a 502 won't bore .090" over then use it stock and make a 549.3" er or bore just .030" over for 556.7"!!!! pdq67 lukeciffer Jun 17th, 07, 08:30 AM thanks for info guys. i think i'm gunna get another 454 cuz they are easy to find. but a .090 over 502 does sound tempting! pdq67 Jun 18th, 07, 06:40 AM Then a 496/505 will be your best bet here. Check Ohio Crankshaft for a decent forged 496 rotationg assembly as well as Speed-O-Motive too! pdq67 and my 496.... 67sprtcp Jun 18th, 07, 05:11 PM Great towing engine in my 03 GMC 2500HD. Plenty of power .Used a quart of oil about every 2,500 miles since new.GM said this was normal. Very reliable. | ||