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Will a stock 427 handle .520 lift?

5087 Views 5 Replies 6 Participants Last post by  dreis454
1969 427/385HP/all stock/app .140 domes/063 heads/10.25 claimed compression.
Seems like a fairly common engine. Certainly someone here has done this cam install. How much valve/piston clearance does the stock cam (461/480 lifts) have and is there ample room for .520 lift?
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For safety/longjevity you REALLY NEED to change the stock springs.

The stock GM springs were marginal for the stock cam let alone more lift and more duration that even a mild perf cam has.

Dont want to chance floating a valve at higher rpms poss leading to a bent valve or worse case maybe poping a retainer/ lock dropping a valve possibly lunching a piston/cyl/block in the process etc.

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