couldn't sleep the other nite so stop fanasizing about my sister-in-law and got to thinking about valve lash. everybody always trying to out-do the solid lifter with a fancy hydraulic type .The idea is to have the hyd lifter already pumped out to the end of its travel and acts like a solid lifter. it cant pump up anymore and hold the valve off its seat or worse. we used to adjust the hydraulic lifters to 0-.005" clearance to mimic a solid lifter, liked to think it helped get a few more RPMS. then the Rhodes lifter came out and was popular for awhile it seems. again adjusted to 0-.005" clearance. Then there is the argument that a hyd cam has "clearance ramps" for the hyd lifter to work properly, so only a dummy would even think of running solids against a hyd camshaft.I always figured a hyd lifter was in essence a solid lifter if it was pumped up solid to the top with oil. Point I am making is if you adjust a hyd lifter to 0-.005" clearance, isnt it a solid lifter??
Well, sorta.... Hydraulic lifters don't become 'solid' until there's enough lifter movement to close off the oil orifice. While adjusting them to the top of their internal travel will prevent 'pump up', there's also the danger that when doing this it puts more stress on the clip that holds the lifter innards in, leading to lifter failure. This is the primary difference between a 'OEM' lifter and an 'anti-pump-up' lifter; a stronger clip. But you still need a bit of movement of the lifter to close the orifice, which is why hydraulic cams have different ramps. The 'Rhodes' lifter is a slightly different deal. Here the lifter is designed to 'bleed down' at lower RPM, in effect reducing lift/duration to improve low speed power, idle quality, and vacuum. It should be noted that all hydraulic lifters will bleed down some, how much has to do with the precision of its internal metering.
"we used to adjust the hydraulic lifters to 0-.005" clearance to mimic a solid lifter," _________________________________________________________ Can you explain exactly how you did this,and how the adjustment stayed at .005 (+ or-), at all times?
Hydraulics are set to zero lash and then a speced lifter preload. It's actually a measurement of the plunger moving down off the clip and against the internal spring. Some manuals state it as a degree of turns but that statement is made after the calculation of thread count per inch over the amount of rotation should equal 0.0xx preload. Zero lash is too loose for hydraulics I ran the Rhodes lifters in a Pontiac with a really lumpy cam. They did exactly what they said they would do and I loved them.
have a solid lifer in my 53 ford, it was my first.love the sound.. have a billet solid roller in my henry j..love it even more..
Eliminating hydraulic lifter pump up is going to reduce the effective cam specs, Timing, IC, lift, duration. You want the lifters pumped up and valves adjusted correctly for that fully pumped up condition, no ?
Why don't you go back to the local track and try and sell your BS there. If you run a hydraulic lifter as loose as you claim you will experience lifter failure @ operational RPM or the push rod will jump (ask me how I know). It will never become a solid ever it will always be hydraulic. They are engineered to be run under a preload as 31vic said, yes you can pick up a couple of hundred RPM by running them loose. I normally even on a stock engine run them looser then the manual says. You have to be careful and it is a balancing act. Too loose and you loose lift or experience lifter failure which could prove catastrophic. I won't bother touching the sister in law thing. Some lines you just don't cross.
I've seen far too many hydraulic lifters fail once the makers all went to the cheap little wire clips. The old hydraulics could run with less preload than the new lifters do, and often 1/4-1/2 turn was fine. But cam makers often recommend 1 to 1 1/2 turns today to keep the lifter from "jumping" and hitting the clip and dislodging it. I've had lifter failures from not enough preload on the new cheap clips, and now I run mine tighter than I used to. I've also had issues with setting lash on some of the newer lifters, and its very important to ensure you are really at zero lash prior to adjusting the preload! I've found that loosening the adjustment off until it starts to click, and then tightening it down until it stops, works best. Then once you've done all rocker adj. you can shut the engine off and add the suggested preload while the engine is off. Running zero, or more lash is a recipe for disaster that you could maybe dodge with the old C clip retainers, but never with the new wire clips.
Most of the dirt oval tracks aound here require hydraulic lifters in the entry level classes like hobby or bomber, so I understand where the OP is coming from. In oval racing, you're always looking for an "edge". Not really enough prize money paid in these classes to make the research financially sensible, but nothing in racing is financially sensible anyway. Would be interesting to experiment with camshaft lobe,lifter, and retainer clip design just to see what could be gained. And it wouldn't surprise me if some of the camshaft grinders who cater to oval racers have already done this. Might be worth some time spent closely reading some cam catalogs from some grinders like Comp Cam.
okay, here we go again. with a solid lifter, after the engine is warmed up, there is very close to 0 lash, right? the solid lifter transmits all the cam lift to the pushrod and valve,right? in a hyd lifter, after it is pumped full of oil, it transfers all the cam lift to the pushrod and valve,right? No difference in performance( and no prformance gain). BUT, when the fu--in lifter pumps up because the spring can't hold the valve in contact with the pushrod and lifter, the lifter pumps up with more oil, holding the valve off its seat and maybe kissing the piston . BAD SHIT! by adjusting the lifter so it CANNOT pump up and gain any length, it prevents the valve from kissing the piston. I don't care about any buloney about max lift and duration, cause it makes no difference if the head of the valve is sticking in the piston crown!!! Never said it waS ROCKET SIENCE, JUST A WAY TO KEEP Ahead of those damned chev ys! 351 clevelands FOREVER!!!!!!!!!!!!!! thanks for your replys, always anxious to learn, even if I don't always agrree. Pictures of my sister-in-law to follow
BUT, when the fu--in lifter pumps up because the spring can't hold the valve in contact with the pushrod and lifter, the lifter pumps up with more oil, holding the valve off its seat and maybe kissing the piston . BAD SHIT! What the hell are you talking about ? Are you talking about weak valve springs that can't follow the cam- and trying to compensate for that?
There's a reason they make a boatload of different valve springs. They have all sorts of varying specs to match any cam profiles you can come up with.
Yeah, they make all sorts of valve springs for sure. But when you're talking about class racing that requires hydraulic lifters, in many cases they also have a spec for max pressure on the seat. I've seen it checked many times in "crate motor" late models.
I used to dislike hydraulic cams for a race or hot street engine, but I did install one in my 545" Mustang(1988GT) and like it just fine. I just put together a 408 cleveland for my grandson's 1973 Mustang, with a Isky RR640 solid roller cam. first time I had a solid roller cam, so am anxious to get it running.
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