whats up with these adjustable pushrods?since buick rockers are fixed on a shaft and not like chevys.what is the rule on running a cam with higher lift?do you have to run adjustables?someone told me you shim the shafts,but that doesnt make sense you would be taking away lift so whats the deal?ive always been a chevy guy but im trying to figure this buick thing out.my buddy has a 454 in his chevelle and when he seen the pistons in my engine he said''damn those are big pistons '',and you know what they are.
A lot of performance cams have a smaller lobe base diameter (to achieve higher lift) this effectively increases the distance between the lifter and the rocker reducing or eliminating the proper valve train preload, also contributing to this is the thicker (than stock) aftermarket head gaskets doing exactly the same thing. Bottom line is you won't know unless you bolt it together and mock up your components.
Also, if you shave your heads, zero deck your block, different head gaskets, you're changing the length needed. T/A does make a variety of lengths of pushrods if you don't want to use adjustable ones.
I run adjustable pushrods in my motor and they have worked great. When I got my car the engine had been rebuilt and the car would not idle correctly at all. Put in the adjustable units and set the lifter preload correctly and it was a night and day difference. They have been in my motor for 2 years with zero problems. I ordered mine from Poston.
adjustables allow you to adjust the valve train like a chevy, and like roller rockers, but a new roller rocker set up will run about $600 for the buick and are not needed till you get into race cams, adjustables are around $150. the buick engine is alot different from chevy and other makes. just my 2 cents
"Put in the adjustable units and set the lifter preload correctly and it was a night and day difference. They have been in my motor for 2 years with zero problems. I ordered mine from Poston" How did you set the pre load? and what did you set it at? I was told by my machinest to set it at .0060 for optimum performance. I think I need to buy adjustables, I checked my preloads today and their all over the place. Dont wat to take chances here, I allready spent about 2,500 on rebuilding this motor and I'm not finished yet
I run them also. You lengthen the pushrod until you take all the slack out of them. Then it's another 1/3 to 1/2 turn to set them. Then just lock down the locking nut and you're done. Pretty simple. It only takes about an hour at most to do all 16.
Preload Adjustment Preload is not critical as long as you are within the specs for the lifter. Hydraulic lifters function to make the valvetrain forgiving, eliminating adjustment as they compensate for wear. Typical instructions that I've seen call for .020 to .060 preload. If you set to the high side (like your engine guy recommends) there is more travel in the lifter to compensate for wear - as the cam lobe, lifter, whatever wears down, the lifter plunger takes up the slack and the preload is reduced. That makes the most sense for a stocker street rebuild, as the engine builder wants to minimize complaints and produce a long running, trouble free engine. Lifters can "pump up" in high rpm applications. This means that the lifter preload gets taken up with oil and the lifter remains extended, keeping the valve off the seat by whatever the preload adjustment is. Some racers recommend setting to the minimum (or even to 0 preload) to avoid pump-up issues. This is not a problem with a street Buick engine - you'd throw a rod before you had a problem with pump-up. I'd set to the mid range, but really anywhere in the recommended range is fine. You can do the turn it until it's tight plus 1/2 to 3/4 turn method, or you can use a right angle rod-type feeler gage under the lifter top retaining clip for a more accurate adjustment.
Ditto on that, thats how you want them for the max horsepower, even a little to much preload will rob power, but it will still run fine and on a street only moter you probaly wont notice.
