I have a similar issue with my hot 360. It will spark knock/detonate only after its driven for a while and in hot summer weather. Currently have rn12yc would rn9yc be a better choice? Otherwise car runs nice and crisp! Car has 3.91's out back a 9.5" FTI 3400-3600 stall converter. 292/508 mopar cam and higher compression kb107 pistons. Also 340 x heads.
