1 FMF

iTrader: (1)

yes. if you have too much preload on the lifters then that can prevent the valve from fully seating = open valve = backfire.

Irocss85

iTrader: (1)

yeah, make sure there adj. right, and make sure they are the correct length.

also, if you did a cranking compres. test, that would answer that for you. atleast, let you know to look closer there or not. if you have less then 150 cranking press, with the sp plugs out, full battery, and the throttle held open. should be in the upper 100's. like 175. seen lots higher then that, but a typical 10.5 compresion sbc will be in that area. sorry for not goin back to remember what your particular eng. setup is. could even be in the really low 200's if you had a high compression motor.

F-Body Lover

whats the stock pushrods length? I checked the suggested parts for my cam and the size was 7.195 I will order few parts soon I guess I will add the pushrods too

F-Body Lover

and yeah I forgot yesterday I toke few pushrods out and a small piece on the side where the pushrods meet the guidplates is scratched bad it was touching the guideplates I will try to take a picture of it

F-Body Lover

here is a picture that shows you what happened to the pushrod

1 FMF

iTrader: (1)

not sure what stock pushrod length is however that value is based on who knows what setup which is based on a block with a certain deck height, lifter size, head, and head gasket. Change any one of those things and that stock length value is incorrect. The smart thing to do is use a pushrod length checker and check your engine so see what you length you need. Google "rocker geometry" for the details, in short you want the wipe pattern that happens on the valve step tip from the rocker arm to be as small as possible and most importantly as centered as possible. You can also observe the wipe pattern resulting from the current set of pushrods and judge whether they're off or not. If your pushrod length is off that won't be the main cause of your current problems but it can result in poor performance at high rpm and will definitely result in short lifespan of the valvetrain and breakage. your pic is blocked for me at my current location, will try to look at it later.