Thread: Engine Combo

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Originally posted by mikekgvk
Hi new-velle,
if your getting 506 ci with a 4.25 crank, then you must have a 4.35 bore. What kind of block are you gonna use? I've read that a standard 454 with a 4.25 bore can only safely be taken .060 over. The tall deck truck blocks can be taken .125 over, so you could safely get the 4.35 bore with the truck block. Or are you going with a bow-tie block?

stock gm block i have bore them to .100 over but i would not do it. it will be junk. 0.060 over would be better if looking for cid run a 4.310 bore and 4.375 stroke and get 510cid and keep the walls from moving and keeping the pistons rings hooked up and on the tall decks this is not true some of the tall decks will not take the.125 bore and over bore more than 0.060 need to be check on all gm blocks. less you have a bow tie than go to 4.500 to4.560