91hatchgt

So as some of you may know, my brother just put GT40X heads on his fox. Well he bolted the stock rockers onto them and torqued to 18ft. lbs... When driving the car, it has a really hard time accellerating but it doesn't pop or sputter at all, it just feels like the valves are really tight. Should he have brought each cylinder to TDC on compression and then torqued to 18 ft. lbs. or does that not matter??? Thanks

mjr46

well if they are pedastal mount stock ones the best thing you can do is trash them....I believe if stock rockers are used on performance aluminum heads ...not sure about the ford ones but any other ones like afr the stock cockers have to be clearanced a little or they will interfere with the retainers on the springs.....but either way..I'd of put a set of roller rockers on.....stock rockers on a performance head = take a step backwards in performance[:'(]

91hatchgt

Thanks, but that didn't answer my question at all.

CHILLERMAN

You need to check the preload on the lifters. 020" to 040" preload is optimum. If you can get access to a comps cam catalog, they have detailed instructions on how to do this. You can also run a compression check. Any valves that are being held open will show-up with little to no compression in that cylinder. Crane makes a very inexpensive shim kit so you can adjust the preload on the lifters that will allow the valves to close. You may have to install shorter pushrods as well. I had this happen to me on my HCI swap, and I have shims on three cylinders. That's the breaks with having a pedestal style rocker. Never again for me.

mjr46

well, what did you expect??? chity stock parts on performance heads = chity results..are you suprised??....anyway, since you want an answer.....here!!......theroreticaly you should always go about checking the valvetrain geometry on any new combo...but if it has a stock cam still and I've done it many times with a stock cam in the motor ...by doing what you just did and bolt them down without checking and been fine....but if you say you lack power....did you check timing??? cause to swap the heads I'm sure you had the dizzy out.....are you a tooth off????..anyway just a though.........it'll be hard to accurately check for proper geometry with the stock rockers..that's why I suggested roller rockers..cause you can make them make a clear contact mark on a valvestem tip that you color with a marker