The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 305 is out 350 is Almost all the way in! (305 autopsy photo's inside!)

rfmaster · 06-03-2011, 01:18 PM

Check Bore diameter - stock 305 should be 3.735 and by the looks of it those pistons look like low grade replacement die cast aluminum (they look like SpeedPro 454NP). If the bore measures 3.765 (+0.030) someone been inside that little poor 305 before and did a half job - replacing OE pistons with non eutectic grade pistons. A truck engine should be built with higher quality pistons capable of withstanding long duration power output periods. A dish piston simply does not have crown material to dissipate heat!

Question - is that Harbor Freight cherry picker you are using to pull that 305 out. Did you have enough lift to clear radiator support??

//RF

06-03-2011, 01:18 PM	#8
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: 305 is out 350 is Almost all the way in! (305 autopsy photo's inside!) Check Bore diameter - stock 305 should be 3.735 and by the looks of it those pistons look like low grade replacement die cast aluminum (they look like SpeedPro 454NP). If the bore measures 3.765 (+0.030) someone been inside that little poor 305 before and did a half job - replacing OE pistons with non eutectic grade pistons. A truck engine should be built with higher quality pistons capable of withstanding long duration power output periods. A dish piston simply does not have crown material to dissipate heat! Question - is that Harbor Freight cherry picker you are using to pull that 305 out. Did you have enough lift to clear radiator support?? //RF __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17)