[Steve C.]

Might be of general interest. Article in the new Hot Rod magazine.....

Improve Top-End RPM by Adjusting Hydraulic Lifters for Minimum Preload


https://www.hotrod.com/articles/adju...e-top-end-rpm/


Information provided in this post does not represent any endorsement. And unless specified it is not based on personal experience and is offered for general interest only

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[tooski]

In the late 70's I bought a publication that describes this. It stated it would allow an extra 500 rpm of capability. When I had a high perf 400 built in the early eighties, I did this. Unfortunately the lifters had the paper clip retainer. I ended up losing a lifter. The engine smoked and sounded so bad I thought I blew a hole in a piston. Changed to an H-O Racing cam and lifters shortly after. All fine since.

[steve25]

Yup! You can never run those type of lifters at true zero, and I found out the hard way just as you did!
I will not take the time to go read that article, but I would hope that they cover that very important detail!
It’s also amazing that in these types of articles they never mention the like ,040” change in rocker arm geometry and the change in valve lift due to that also!

[ponjohn]

Isn't that the premise of the short travel Johnson lifters?

[tom s]

I sat across the deck of a local cam grinder a week or so.Found it interesting that he will only use standard hyd roller lifters in street builds with 6000 RPMs or less with 160 on the seats.He NEVER uses short travel or super hipo lifters.He has less issue with ALL brand of lifters and engines with the standard lifters.FWIW,Tom

[Steve C.]

Steve Brule at Westech Performance is another advocate for higher seat pressure with hydraulic roller lifters. Some would come unglued at the suggestion of the spring pressures that Mr. Brule is using on hydraulic rollers to control the valves.

For interest note the valvespring pressures here:

https://www.hotrod.com/articles/ccrp...ustion-engine/

And please do not shoot the messenger because it's not a 5000 rpm truck motor ! Posted for conversation only.


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[steve25]

Well, I never looked into what the average added weight a Hydro roller lifter is over a non roller lifter, but I would not be surprised if its 25% which would then call for a 25% higher spring rate.

[JSchmitz]

Originally Posted by steve25

Well, I never looked into what the average added weight a Hydro roller lifter is over a non roller lifter, but I would not be surprised if its 25% which would then call for a 25% higher spring rate.

I don't think there's a direct percentage correlation between static weight difference and spring force requirements. Not sure what factor more the dynamic load would be. Engineers?

[DiamondJim]

Yea I tried this in 1970. Bad idea! Don’t do it!

[steve25]

Yup, there's likely a tie to the rocker ratio and the spring force transmitted back to the push rod or something of that nature.

[Cliff R]

Interesting? I think I've been recommending adjusting lifters up from bottom out vs down from zero lash for several years now.

I found out EXACTLY what they mention WAY back when I set-up my first Pontiac 455 engine with the excellent HT-951R lifters (special retainer to not only retain the plunger but decrease it's travel at the same time).

I pounded the "special" retainer out of one of the lifters and realized that running just a fuzz past zero lash was NOT a good idea. For decades I'd been running small block Chevy "stock" and "claimer" 350 circle track engines I've built here by adjusting the plungers bottomed out with a .010" feeler gauge between the valve tip and rocker arm and they spun up to really high RPM's w/o any issues. Of course there is absolutely NO MONEY coming your direction from that sort of work (unless you take used truck tires with only one or two plugs in them for payment!) so I had weaned myself off of that deal by the late 1990's.

Hum, wonder how this would work on a street engine that doesn't see nearly the RPM's? Plus the HR lifters were becoming popular and we were seeing all sorts of issues with them, excessive noise was among them. As the manufacturers were making changes to them to reduce plunger travel and stiffer spring under them I simply started "tight lashing" them about 1/2 turn UP from the plungers bottomed out vs down from zero lash.

That ended the noise issues and all of the HR engines I built and dyno's ran flawlessly everyplace.

So it appears that there are not only positives from noise reduction waiting for us there is also a potential performance improvement at high RPM's.........Cliff

[steve25]

Cliff, do you think that adjusting them that way which I guess first bleeds most of the oil out of them helps them to hold there adjustment better when running?

[Cliff R]

Not sure about that but for sure it ABSOLUTELY insures that you adjust them correctly. Running them down to "zero" lash isn't near as easy as it can be difficult to tell exactly when you take up all the slack in the parts vs completely compressing the plungers and "locking up" the pushrods so you know for sure all the slack is out of the associated parts.

I like to use a feeler gauge vs number of turns, and use the same procedure to determine pushrod length required for best geometry as well.......

[JSchmitz]

Originally Posted by Cliff R

Not sure about that but for sure it ABSOLUTELY insures that you adjust them correctly. Running them down to "zero" lash isn't near as easy as it can be difficult to tell exactly when you take up all the slack in the parts vs completely compressing the plungers and "locking up" the pushrods so you know for sure all the slack is out of the associated parts.

I like to use a feeler gauge vs number of turns, and use the same procedure to determine pushrod length required for best geometry as well.......

Cliff, How do you get them down to the bottom after they have been pumped up? Maybe you've talked through it before and I've forgotten. Seems like this could take time if you have to keep cranking them and waiting for them to bleed off. How are you sure when they are at the bottom vs. still on hydraulic? I've never had any problem seeing and feeling when I'm at zero lash.

[Jay S]

If the lifter is a certain percentage heavier it would not be a straight up change with the seat pressure. The rocker arm ratio changes the effect of the mass on the lifter side of the rocker fulcrum. If you wrote an equation to calculate the needed spring pressures only part of the equation would be for the lifters mass and acceleration, and the equation would have a input for the rocker ratio. The reaction vectors forces between the roller lift and the lobe are different than a flat tappet also. It is more difficult to keep the lifter forced down on the roller set up than the flat tappet set up. Some of the seat pressure switching to a roller set up increase comes from that.

I have never been on board setting the lifters at the top of the travel. We always considered it a bandage trying to correct another issue. Some of the issues seem like they are worse depending on how the lifter oil galleys are fed. We have had the most issues with Fords pumping up lifters. Never seen it on a Pontiac that I recall. Have spun some mopar with hydrualic cams extremely hard, 7 to 8 K, never even looked at the preload on those.

Makes sense on some engine to set the lifter at the bottom to me.

[pontbil]

Originally Posted by Cliff R

Interesting? I think I've been recommending adjusting lifters up from bottom out vs down from zero lash for several years now.

I found out EXACTLY what they mention WAY back when I set-up my first Pontiac 455 engine with the excellent HT-951R lifters (special retainer to not only retain the plunger but decrease it's travel at the same time).

I pounded the "special" retainer out of one of the lifters and realized that running just a fuzz past zero lash was NOT a good idea. For decades I'd been running small block Chevy "stock" and "claimer" 350 circle track engines I've built here by adjusting the plungers bottomed out with a .010" feeler gauge between the valve tip and rocker arm and they spun up to really high RPM's w/o any issues. Of course there is absolutely NO MONEY coming your direction from that sort of work (unless you take used truck tires with only one or two plugs in them for payment!) so I had weaned myself off of that deal by the late 1990's.

Hum, wonder how this would work on a street engine that doesn't see nearly the RPM's? Plus the HR lifters were becoming popular and we were seeing all sorts of issues with them, excessive noise was among them. As the manufacturers were making changes to them to reduce plunger travel and stiffer spring under them I simply started "tight lashing" them about 1/2 turn UP from the plungers bottomed out vs down from zero lash.

That ended the noise issues and all of the HR engines I built and dyno's ran flawlessly everyplace.

So it appears that there are not only positives from noise reduction waiting for us there is also a potential performance improvement at high RPM's.........Cliff

I have taken Cliff's advise and adjusted lifters this way for sometime and I cant say I have seen any performance increase. When adjusting them from the bottom up you may need a longer push rod

[Cliff R]

Lifter quality isn't all that great these days and from what I've seen here leaving a lot of room under the plungers will pretty much guarantee a "ticker" or two in the bunch, at least if you have my luck with this sort of thing.

That is NOT what the customer wants to hear after you talked him into the $1200 roller lifter "upgrade" so I run my engines tight-lashed to take that deal out of the equation. If you get away with leaving a ton of room under the plungers that's great, but more times than not you'll end up with a noisy valve train once the engine is well heat soaked and oil thinned out some......FWIW......

[Cliff R]

"I have taken Cliff's advise and adjusted lifters this way for sometime and I cant say I have seen any performance increase"


In theory you should NOT see any "performance increase". Oil is basically NOT compressible and at speed the lifter should act like a solid lifter less any very slight bleed-down. What you will help is noise or "ticking" as lifter to plunger tolerances and leak down rates aren't nearly as consistent as they should be with many of these parts.......

[JSchmitz]

Didn't this whole 1/4-1/2 turn after zero lash start a long time ago to help prevent "floating the valves"? Seems like I remember that from back in the day.

[Steve C.]

Not suggesting this comment from a Comp Cams article directly applies to the topic at hand here. Adjusting the lifter changes the variables. But I posted it before and felt it was interesting....

To complicate matters a hydraulic lifter acts like a shock absorber, the lifter "gives" just a little as you load it under under running conditions. From their Spintron research engineers at Comp Cams actually see running valve duration decrease as rpm increases due to this increased inertial loading. The faster the cam spins, the harder it hits the "shock absorber", and the lifter loses some valuable duration as a result. Their data indicated a "real world" dimension for a running engine with hydraulic lifter tappets.

Example the popular XE hydraulic roller lobe 3315 rated 230 degrees at 0.050".
With a 1.5 ratio rocker ratio the static duration measured 'at the valve' is 243 degrees at .050" tappet lift. However at that same .050" tappet lift under actual running condition it was measured with 240 degrees 'at the valve', or a loss of three degrees duration.

Further under actual running conditions with other lobes and variables involved there can be as much as 10 degrees less seat duration.


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