Hydraulic lifter preload...who really checks this?
No.
First off, I never said anything, I wrote some things.
Secondly, I never built a race oriented small block where issues such as these would seem to be more crucial. Nice try at an underhanded insult. It didn't slip right by me at all.
I've built a few engines but never anything with the intention of drag racing. I run my stuff on the street for occasional fun or for daily driving. It would seem that measuring preload on a fairly stock engine is a matter of splitting hairs on whether or not it will make a difference. Stock head gaskets were often .020 steel, replacements are often double that but when a surface cleanup head milling and block decking are done, you often end up close to where the deck clearance was originally.
I've built a few big blocks and have gone into greater detail with assembly and adjustments. That wasn't the point here. I'm told that the Mopar lifters had a greater amount of preload than some other brands but I was curious as to how crucial that was since I hadn't seen any adverse effects to date.
If you aren’t checking preload one issue that crops up fairly often (not as much as it used to for the reason I’m about to say) is you have too much preload.
This happens with old heads that have had 3,4,5 valve jobs and the machinist didn’t correct stem height by not knowing to do it or not giving a ****.
The extra stem height raises the valve side of the rocker and that in turn lowers the pushrod side of the rocker.
That adds more preload. Those same heads will have been milled several times too. That lowers the head, lowers the rocker and increases preload.
Now what happens if the block has been deck a couple of times? It effectively lowers the head which lowers the rocker which increases the preload.
At some point you get the place where the lifter holds the valve open. Maybe not enough to miss but enough to keep the valve from dissipating heat through the seat because it’s hanging open a bit.
Next thing you know, you’ve got a burned valve.
Other **** happens too. Like a guy who has no clue about no adjustable shaft rocker systems and he throws a .100 long valve in there.
You can’t grind the stem down .100 to correct it or you ruin the valve. Now the geometry is whacked and you have too much preload and the calves don’t seat and you get a miss.
One last thing. I know guys get away with those cheap assed straight shims that just raise the shaft. Guys do it but they can break the stand and the kill geometry. Your better off not using them and living with the already bad geometry rather than using those shims and adding to the geometry issues.
I know damn good and well Dave Hughes knows this because we’ve talked about it. I didn’t care for his answer about why he uses them but he knows they are wrong. Our disagreement is I say it makes the geometry worse and he says it doesn’t make it THAT much worse.
If you need to shim the stands spend a bit more cash and get the proper shims from Mike at B3 racing engines.