Ok i have some 317 heads already on my truck i want to change them to 243s i just bought some yella terra 1.85 rockers and will be installing 220r cam from TSP. I am just wondering the best heads to use for this cam and rocker setup? and wondering what size rods i would need? any help would be great .

 

The heads are the same design as the 317 's they are just (243=63.5cc) (317=72cc) the same as the 243 just smaller chamber . So it would bump compression up about 1 full point, as for the 1.85 rockers that qeustion has been asked many time ( including by myself) and the experts on here agree the change in ratio doesn't give a lot of power gain and it makes selecting a cam more difficult.. The pushrods are a tricky one because if you change the cam lobes a lot then going stock length pushrods may not work. Best thing to do is get a pushrods length checker and know for sure the proper length. There are to many variables that will effect the length for example milling the heads or the block deck surface , changed head gasket thinkness , and cam lobe. And finally for a cam selection I would check with Pat G from the guerra group. He custom specs cams specifically taylored to you setup and likes. He speced a cam for me and I'm extremely happy. Hope this answer helps