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Ideal lifter preload on a hydraulic roller setup

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Ideal lifter preload on a hydraulic roller setup

Postby bob cook » Tue Sep 13, 2005 2:32 pm

Just curious if anyone has experimented on the track or dyno with lifter preload on a hydraulic roller setup? I've been told everything between 1/4" turn to just touching.
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Postby airflowdevelop » Tue Sep 13, 2005 2:37 pm

you are not getting away that easy bob....you need to answer a couple of questions first.

valvetrain mass?
what lifter?
pushrod length?
spring pressure?
duration @ .006,.050,.200,.250?
RPM desired?

Their is no easy answer, just easy questions.

Can you run OE ford and gm lifters with lash....SURE. but what does it do? How long will the poppet last? how long will the roller last?

these are the things we have to answer. Also, harmonically this can become an issue of you come into the rebound of the poppet.

Dennis
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Postby bob cook » Tue Sep 13, 2005 4:20 pm

Darn. I thought there would be a canned answer for this one. 68 gram IN, 62 gram EX valve, 6.88 gram retainers w/3 to 4 gram per pair locks, Stock replacement FRPP lifters. Pushrods are hardened 6.450" .080 wall w/.040 restrictors. Springs are 165lb seat and 400lb at .550. Cam is 244/256 @ .050. I think there are numbers for .006 on my cam card but, I need to get it from home. I've experimented with shift points and the car seems to like 7,200 to 7,400rpm. The shaft rockers are custom lightened 1.6:1 Harland Sharp.
Thanks
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Postby airflowdevelop » Wed Sep 14, 2005 8:07 am

Bob,
I would start at zero lash...if the lifters are in good shape. I assume this is a sbf. They have a fairly tight valvetrain package. we have gone as much as .006 lash with good springs and not had any problems in purpose built racers.

Dennis
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Postby katman » Wed Sep 14, 2005 10:41 am

OK, I'll show my ignorance here, and I can do it pretty well too, but why do you want lash on a hydraulic lifter? I'm a sbc person and we have always gone 1/2 to a full turn down from zero.
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Postby bob cook » Thu Sep 15, 2005 7:25 am

I'm also curious of what effect the zero to .006 lash will have from a performance standpoint vs. preloading the lifter. Would it act more like a solid lifter with no preload? I also run about 80-90 psi of oil pressure. Not sure if this is important with the oem lifters. Thanks, Bob
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Postby katman » Thu Sep 15, 2005 2:20 pm

Maybe at slow speeds it bleeds down and works normal but at higher speed it pumps up for quicker and higher lift????
Don't leave us hanging, TELL US!!!
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Postby airflowdevelop » Thu Sep 15, 2005 3:19 pm

even with the smallest amount of preload, with high oil pressure, and especially higher RPM where the lifter is getting filled quicker, it has a tendency to overcome some of the spring pressure and leave the valves open....thats about the easiest way I can explain it...their are also a couple of other demons this helps with, but this is the main reason.

Thanks
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lifter preload

Postby Adger Smith » Fri Sep 23, 2005 3:20 pm

I have found that BBC hyd rollers are all subject to the lifter pumpup at above 6,200 on my dyno. This is with std weight valve pieces & springs that have 400 open. Seat pressure doesn't seem to have an effect. When you lash the valves like a solid @ .004 to .006 it extends the rpm range. I also try to use a thin oil(20-50) & no more than 60 lbs oil pressure at RPM. I have had good luck with this in some of my boat customers engines. I have had one that had real large heavy intake valves (furnished by the customer) that could not be run over 6,000 with out float or lifter pump problems. I have seen some lifter problems if spring pressure was increased to more than 450 open. In the future I have been considering heavy oil in one. Anyone have any thing to share?
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Postby airflowdevelop » Fri Sep 23, 2005 3:54 pm

a 30 weight synthetic will help, and you can pop the pump at 50lbs with a little more rod clearance. Should have little effect on a endurance engine.

If the lifter is design correctly, you can install a hardened tru-arc in place of the flexible junk from the factory.
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preload

Postby automotive breath » Fri Sep 23, 2005 6:08 pm

Maybe I’m missing something but aren’t hydraulic camshafts ground to be run with preload? I can understand when valve float becomes a problem, setting them at zero or with lash may eliminate the valve float, but isn’t this just a quick fix. The ramps aren’t designed to run with lash. When I'm looking for upper RPM power I chose a solid
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Postby shawn » Fri Sep 23, 2005 6:43 pm

Hi,
automotive breath-
i have always believed that you should go to a solid roller too, but sometimes because of application or user inexperience, it's not always doable.I have a great customer that i wouldn't trust to get the valve cover off,let alone adjust the valves or even know what he was looking at. He likes power though and doesn't want problems, so hyd. rollers are usually what he ends up with.While the ramps are designed not to have lash, i haven't yet seen where .004 (the most i've ever ran) has had any effect on life of parts. It does make them a little noisy though.
Adger-
Have you tried modifying a rev kit for it?I've used the AFR ones on the small blocks and they work really well. I did a BB Chev for my dad's suburban with a hyd. roller and toyed with the idea, but ran out of time to apply it. I don't think it would take too much work to get it on there and would really help those heavy valves over 5500 rpm.
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Lifter preload

Postby Adger Smith » Fri Sep 23, 2005 7:11 pm

Shawn,
Yes, I have bought one rev kit seemed to fit nicely. I had to modify the alum. piece that fit the lifter top. The customer didn't like the added expense. Just couldn't understand what was happening.
Yes you are right about the proper use parts for customers. These boat guys don't want to work on anything except their cup holder. (for their favorite beverage) I try to keep the Rpm's down so they will live a little longer too.
As for the oil: I am not a fan of synthetic oil in new engines. I would rather run conventional oil to seat everthing that need a little breakin. I have a couple of customers that have changed the Castrol race oil to Mobile 1.
I like the race oil because it doesn't foam and froth at high RPM.
Has anyone tried the Sherman modified lifters in an endurance application?
I think they are modified to only have .015 plunger travel. I have a couple of NHRA Stock elem. customers that use them.
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Re: Lifter preload

Postby automotive breath » Fri Sep 23, 2005 8:00 pm

Adger Smith wrote:Shawn,

Has anyone tried the Sherman modified lifters in an endurance application?
I think they are modified to only have .015 plunger travel. I have a couple of NHRA Stock elem. customers that use them.


They are very common around no problem raceway with the stockers, I haven’t heard any complaints. From what I here you send him a set of lifters and he eliminates most of the plunger travel for a fee. I don't know if the endurance people have tried them.
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Postby bob cook » Mon Sep 26, 2005 7:34 am

There are a few places that do the lifter travel mods but, basically it violates the stock lifter rule in the NMRA. I did go from my normal 1/4 turn to 1/8 turn but, didn't notice any difference during testing. I can't get myself to go to zero lash. I may try it this weekend in BG at the NMRA final event.
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