I have a new set of hot heads adjustable push rods, new lifters, and a reground cam. I have one pushrod that spins like crazy! It's a little noisy but I have never seen anything like this.
Is it adjusted the same as the others ? have you compared it to another pushrod ? Could it be machined or ???? Something wrong and be defective. how much faster is it spinning ? On what cylinder ? Intake or exhaust ? Bad slightly collapsed or shorter push rod ? I dunno man I’m just throwing stuff out there strange issue you have . observation will be the key to success on this one !
The spinning lifter is causing the pushrod to spin. It's not the "ramp" that may be excessive, but the angle that the lobe is ground at, that "makes" the lifters spin. Could that lobe have too much angle...don't understand how, but most anything is possible. I'd give that lifter a check every now and again to make sure that it's in good shape and not eating itself and the cam lobe. Mike
The cam lobe is causing the spin. Move the pushrod in question, and I suspect the spin will stay with the lobe, not the pushrod. If it stays with the lobe like I suspect, try a different lifter. The other possibility is that the lifter bore isn’t parallel to the others.
pushrod spin is a result of lifter spin caused by the crown on the lifter face, the lobe design and most engines have the lifters offset to the cam lobe...
Not exactly easy to check on. I will move the pushrod and see what happens. They all spin slowly, just this one is way faster. The engine isn't broke in, I'm hoping it will calm down. Lifters seem noisy at this point too.
I need some of you Lifter Scientists to school me as needed. Is a bad lifter that doesn't pump back up as fast as the other "normal" ones also a possibility?? I'm wondering if that's why it checks out when it's adjusted with the engine at rest, but noisy and possibly loose when under operating load.
The looser the adjustment, the faster a lifter/pushrod will spin. If one spins more than others, it's likely got more lash than the others.
@1971BB427 that sounds reasonable. I am going to try a more scientific method of adjustment tomorrow. Set the pushrod to slight drag, then put .020 preload with a dial indicator to measure it.
The hydraulics I set with a dial indictor at .050 - .060. If you were comparing it to a small block that would equal the one turn that is a common adjustment. The slow turning of a lifter is to keep them and the lobe from wearing.
Yes, don't get them too tight! If they don't turn much, they'll wear out, not oil properly, or not let the valve fully close.
What weight oil are you running? Lifters like a multi-weight oil, like a 10W-40. I prefer Lucas Hot Rod for high zinc content. Joe
Curious on the pushrods wearing if they don’t turn, what happens with a roller lifter and the pushrod?
The pushrod spin is a result of the lifter spin. Flat tappet lifters need to spin so as not to wear the cam lobe. Roller lifters don't need to / can't spin.
I guess my question was more in regards to replies that indicated the pushrod needs to spin or it will wear.
Got it sorted today. Did a careful job of setting the valves and gave them one full turn of preload. About .030. It seems to be about right. I had a couple set with more than that and that bank of cylinders got noisy.
Btw ford small blocks with roller lifters used hardened pushrods in cop cars and taxi cabs. They actually wear the rockers out. Mustangs got soft shit pushrods.