i guss i should just keep quite because my block is a xr2 & not a xr1,but i do know my machinest told me that almosy all brand-x blocks & dart included have most of the same problims my ritter block had,when ryan put my lifter bushings in he would not start untill i sent him my cam,lifters, cam bearings, he said allmost every engines lifter bores are off, so you need a jig to aleign them corectly,not just kents,only real problim i had was with the maching work that was done before i got mine,kent madeit all good, & i ask ryan if it was fixed right & he said everything was ok,my xr2 block is for the p7 heads only,the wedge heads & cam will not fit, iwas toold when i bought my xr2 that it would have to be bored,alined honed,bussings installed if i wanted keyway lifters, as well as the deck cut to my spects, so i think i got what i payed for,nothing special