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Author Topic: Lifter pump-up: what, why, when, and how to prevent it?  (Read 4007 times)
Johnunit
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« on: April 12, 2011, 06:55:36 pm »

I've seen references out there to lifter pump-up at high RPM, and using Engine Analyzer Pro I get "lifter pump up" at higher rpms along with a steep drop in power when simulating very high lift and aggressive ramp cams.

What is actually happening to the lifter and the valvetrain above it when pump-up occurs, and how can it be predicted and/or prevented? Is this something "better" parts can reduce the occurence of? Is it damaging, pistons potentially hitting valves or something like that?
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« Reply #1 on: April 12, 2011, 09:03:14 pm »

Are you talking about hydraulic roller lifters?
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Robert's 1969 Mercury Montego (FordStrokers 408W, QFT 850cfm RQ-AN, Super Victor, 2" aluminum open spacer, CamMotion HR .624/.609 251/256 108, 1-3/4" x 3" headers, Broader Performance RmV/B under a C6/4R100 behind a 8"/9" billet 5500 stall, 9" 4.56 Detroit Truetrac, M/T ET radial streets 315/60-15 on 10" rims)

The Merc started here = http://sbftech.com/index.php/topic,27178.0.html

Irwindale Speedway 1/8 mile (1st time at a track!) = 7.647 @ 90.78mph with a crappy 1.878 sixty foot (3850# race weight)

Present day Merc = http://sbftech.com/index.php/topic,34648.0.html


Except that engine building (properly) is a labor intensive industry.  Who do you think does all the measuring and machining?  Little engine shop fairies?  Not to mention assembly, mock up and parts fitting.

At Woody's level you are not just paying for his labor but for his skill set as well.

Thanks FordStrokers 408W, Westminster Performance Transmission (W.P.T.) transmissions, TCS Performance converters, Broader Performance valvebodies and last but not least a BIG thanks (always) to my friends here and abroad in the World!
Johnunit
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« Reply #2 on: April 12, 2011, 09:46:52 pm »

yes.
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1985 Crown Victoria - 351 being built for the spring
85_GT
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« Reply #3 on: April 12, 2011, 11:32:59 pm »

The way I've always understood it, and this site may correct me, is that properly set, you have some preload that depresses the piston in the lifter a certain amount.  When you get into RPM's where the springs can no longer keep the lifter on the cam, you start getting some clearance.  With this clearance, the hydralic lifter trys to take up the slack.  It can only do this to the amount it was originally depressed.  That's the 'pumping up'.

What happens when that happens is that now the lifter is effectively too long that when the valve should be closed, it nolonger is.  It's left slightly off the seat by that slack amount times your rocker ration.  Hence, power drops off as the valves don't close completely on compression and power stroke.

Better parts (lighter and better matched springs and their rates) and limited preload lifters help this problem by helping keep the contact all the time.  As far as damage, the lifter would most likely lose contact as it's coming over the nose.  Piston is not near that event.  However, once it gets pumped up.  You'll have a closer piston to valve clearance the what you measure.  If you were close, you'll be that much closer.  With a preload of say .030 would get you about .048 less clearance ideally with 1.6 lifters.
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85GT, Dart Windsor Jr, Crane 2030 equiv. Performer 5.0, 75mm TB, 88mm Slot, 34lbs injectors, 1 5/8" shorties, 5spd converted to 4R70W with Baumann controller, 3.25 9"
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Joel5.0
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« Reply #4 on: April 13, 2011, 12:27:40 pm »

Pump-up = preload cancellation causing the valve not to close by the same amount the preload is set at x rocker ratio.

IOW.... a lifter with a preload of .040" will cause the valve to stay open .040" x rocker ratio when pump-up occurs.
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Quote from: Joel5.0
The right to be stupid is inalienable for sure however, there is no such thing as a right to impose stupidity onto others
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A mind is like a parachute it only works when it is open.  (oldmanjoe)
If you can't explain it simply, you don't understand it well enough. (Albert Einstein)
Tuning on a Dyno for the track, is like swim practice in a bathtub.
I can explain it for you, but I can't understand it for you. (90lxcoupe)
The proof of understanding is the ability to explain it. (H. Torruella)
Ignorance is bliss, but stupidity is orgasmic.
Fraud and falsehood only dread examination. Truth invites it. (Samuel Johnson)
The chaotic resistance of the opponents leads to the conclusion that they are not prepared to meet the challenge. The problem is already much more psychological then technological. [Bojidar Djordjev]
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« Reply #5 on: April 13, 2011, 12:38:55 pm »

What about hydraulic lifters problems in the upper rpm range because they weren't getting enough oil?  (IIRC collapsed lifter syndrome?)
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Robert's 1969 Mercury Montego (FordStrokers 408W, QFT 850cfm RQ-AN, Super Victor, 2" aluminum open spacer, CamMotion HR .624/.609 251/256 108, 1-3/4" x 3" headers, Broader Performance RmV/B under a C6/4R100 behind a 8"/9" billet 5500 stall, 9" 4.56 Detroit Truetrac, M/T ET radial streets 315/60-15 on 10" rims)

The Merc started here = http://sbftech.com/index.php/topic,27178.0.html

Irwindale Speedway 1/8 mile (1st time at a track!) = 7.647 @ 90.78mph with a crappy 1.878 sixty foot (3850# race weight)

Present day Merc = http://sbftech.com/index.php/topic,34648.0.html


Except that engine building (properly) is a labor intensive industry.  Who do you think does all the measuring and machining?  Little engine shop fairies?  Not to mention assembly, mock up and parts fitting.

At Woody's level you are not just paying for his labor but for his skill set as well.

Thanks FordStrokers 408W, Westminster Performance Transmission (W.P.T.) transmissions, TCS Performance converters, Broader Performance valvebodies and last but not least a BIG thanks (always) to my friends here and abroad in the World!
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« Reply #6 on: April 13, 2011, 01:49:20 pm »

  Why is there less oil at high RPM?  Where else is it going?
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85GT, Dart Windsor Jr, Crane 2030 equiv. Performer 5.0, 75mm TB, 88mm Slot, 34lbs injectors, 1 5/8" shorties, 5spd converted to 4R70W with Baumann controller, 3.25 9"
A9L running A9P bin via Quarterhorse with LC-1
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« Reply #7 on: April 13, 2011, 03:57:36 pm »

Why is there less oil at high RPM?  Where else is it going?


Gets pushed out of the lifter by high rpms and doesn't have time to get replaced?  (Bad lifter design?) 
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Robert's 1969 Mercury Montego (FordStrokers 408W, QFT 850cfm RQ-AN, Super Victor, 2" aluminum open spacer, CamMotion HR .624/.609 251/256 108, 1-3/4" x 3" headers, Broader Performance RmV/B under a C6/4R100 behind a 8"/9" billet 5500 stall, 9" 4.56 Detroit Truetrac, M/T ET radial streets 315/60-15 on 10" rims)

The Merc started here = http://sbftech.com/index.php/topic,27178.0.html

Irwindale Speedway 1/8 mile (1st time at a track!) = 7.647 @ 90.78mph with a crappy 1.878 sixty foot (3850# race weight)

Present day Merc = http://sbftech.com/index.php/topic,34648.0.html


Except that engine building (properly) is a labor intensive industry.  Who do you think does all the measuring and machining?  Little engine shop fairies?  Not to mention assembly, mock up and parts fitting.

At Woody's level you are not just paying for his labor but for his skill set as well.

Thanks FordStrokers 408W, Westminster Performance Transmission (W.P.T.) transmissions, TCS Performance converters, Broader Performance valvebodies and last but not least a BIG thanks (always) to my friends here and abroad in the World!
85_GT
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« Reply #8 on: April 13, 2011, 04:26:18 pm »

Hmmm... what is pushing it out?  The increased inertial force of trying to open the valve faster?  It's a thought.  That force would have to be great enough to make the 'bleed' rate higher then the faster pumping oil, no? 
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85GT, Dart Windsor Jr, Crane 2030 equiv. Performer 5.0, 75mm TB, 88mm Slot, 34lbs injectors, 1 5/8" shorties, 5spd converted to 4R70W with Baumann controller, 3.25 9"
A9L running A9P bin via Quarterhorse with LC-1
Johnunit
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« Reply #9 on: April 13, 2011, 07:13:00 pm »

thank you all. Very helpful responses.
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« Reply #10 on: April 15, 2011, 12:43:45 pm »

what effect does a high volume or high pressure oil pump have on pump up?
Can it cause it at a lower rpm?
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« Reply #11 on: April 15, 2011, 12:46:57 pm »

what effect does a high volume or high pressure oil pump have on pump up?
Can it cause it at a lower rpm?


My understanding is that "pump up" is caused by an unstable valvetrain with the main factor being wrong or faulty valve-springs and not higher oil pressure, right?
Logged

Robert's 1969 Mercury Montego (FordStrokers 408W, QFT 850cfm RQ-AN, Super Victor, 2" aluminum open spacer, CamMotion HR .624/.609 251/256 108, 1-3/4" x 3" headers, Broader Performance RmV/B under a C6/4R100 behind a 8"/9" billet 5500 stall, 9" 4.56 Detroit Truetrac, M/T ET radial streets 315/60-15 on 10" rims)

The Merc started here = http://sbftech.com/index.php/topic,27178.0.html

Irwindale Speedway 1/8 mile (1st time at a track!) = 7.647 @ 90.78mph with a crappy 1.878 sixty foot (3850# race weight)

Present day Merc = http://sbftech.com/index.php/topic,34648.0.html


Except that engine building (properly) is a labor intensive industry.  Who do you think does all the measuring and machining?  Little engine shop fairies?  Not to mention assembly, mock up and parts fitting.

At Woody's level you are not just paying for his labor but for his skill set as well.

Thanks FordStrokers 408W, Westminster Performance Transmission (W.P.T.) transmissions, TCS Performance converters, Broader Performance valvebodies and last but not least a BIG thanks (always) to my friends here and abroad in the World!
Joel5.0
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Location: Puerto Rico
Miracles?.... by appointment only!


« Reply #12 on: April 15, 2011, 01:28:23 pm »

what effect does a high volume or high pressure oil pump have on pump up?
Can it cause it at a lower rpm?


My understanding is that "pump up" is caused by an unstable valvetrain with the main factor being wrong or faulty valve-springs and not higher oil pressure, right?

Nope....... simpler..... higher RPM = max oil pressure, lifter cannot bleed off fast enough, lifter becomes solid taking out the preload out of the picture = valves not closing/seating.
Logged

ACRONYMS:
LUK  LMK  JIC  BTSTDTRT  YCYDYP  NFI-YTM  SPOBI, and the classic... DILLIGAS

'86 Mustang GT, X-303 cam, Holley DP 700, RG Tran., 289 Heads   Ford Smilie 2


Quote from: Joel5.0
The right to be stupid is inalienable for sure however, there is no such thing as a right to impose stupidity onto others
Great Thoughts will Overwhelm a Feeble Mind
There is never money to do it right, but there's always money to do it over.
Knowledge based on external evidence is unreliable.
He, who doesn't ask, does not deserve an answer.
A mind is like a parachute it only works when it is open.  (oldmanjoe)
If you can't explain it simply, you don't understand it well enough. (Albert Einstein)
Tuning on a Dyno for the track, is like swim practice in a bathtub.
I can explain it for you, but I can't understand it for you. (90lxcoupe)
The proof of understanding is the ability to explain it. (H. Torruella)
Ignorance is bliss, but stupidity is orgasmic.
Fraud and falsehood only dread examination. Truth invites it. (Samuel Johnson)
The chaotic resistance of the opponents leads to the conclusion that they are not prepared to meet the challenge. The problem is already much more psychological then technological. [Bojidar Djordjev]
Individuals are rational and humane... Crowds are reactionary and barbaric. (Jason)
The person who says it cannot be done should not interrupt the person doing it. –Chinese Proverb
Nothing sways the stupid more than arguments they can't understand - Cardinal de Retz
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