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Re: poly 318 stuff

From: Hank Dozier
Date: March 04, 2002


The 277/301/303/313/318/326 Poly engine stuff will not fit the Dodge 325. This block was based on the low-deck 241/260/270 unit, and with exception of stuff like distributor drive bushing and timing chain setup, both are unique. The high-deck Dodges were made in 2 displacements (315 and 325), and both have hemi and poly variants. Best "speed" stuff for a 315/325 poly is cam from a 1957 KD500 hemi or something close, aftermarket 2x4bbl or 3x2bbl (or take a hemi/poly stock 4-bbl and bore the mainifold to accept the Edelbrock carb bores and drill for the rectangular carb spacing). The heads have 1.84" intakes and 1.51" exhaust valves, and these can be increased to about 1.9" and 1.6" respectively. Put some good valve springs on and bronze valve guide inserts in and use 11/32" valve stems to get more airflow. Port match the intakes and exhausts to the gaskets and manifolds, and use pistons that give about 9.5:1 compression ratio. That and the low restriction header exhaust, and you should have more than enough tractable power.


Last changed: July 19, 2018