Shimming Hyd Flat Tappet Lifters

[vortecpro]

What gains in dyno HP, MPH, RPM peak gains have you seen from shimming hyd flat tappet lifters on a stocker cam? Is it possible a hyd lifter with .400 lift @ the valve with 170 on the seat with 350 open with a agressive lobe could cause the lifter to collapse @ 6000 RPM.
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[Walter R. Malik]

What gains in dyno HP, MPH, RPM peak gains have you seen from shimming hyd flat tappet lifters on a stocker cam? Is it possible a hyd lifter with .400 lift @ the valve with 170 on the seat with 350 open with a aggressive lobe could cause the lifter to collapse @ 6000 RPM.
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In some hydraulic roller applications ... 100 horsepower at higher RPM.
In hydraulic flat tappet applications it would depend a whole lot upon valve spring pressures.

[cgarb]

What would it hurt to try? Other than your wallet...lol.

[Casper393W]

What gains in dyno HP, MPH, RPM peak gains have you seen from shimming hyd flat tappet lifters on a stocker cam? Is it possible a hyd lifter with .400 lift @ the valve with 170 on the seat with 350 open with a aggressive lobe could cause the lifter to collapse @ 6000 RPM.
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In some hydraulic roller applications ... 100 horsepower at higher RPM.
In hydraulic flat tappet applications it would depend a whole lot upon valve spring pressures.

I would say he is on the tip of it with 350lbs open pressure, depending on the quality of the lifter.... Unfortunately you won't know until you test!

[blwilliams]

OK I must admit I'm a bit naive/confused here.
Can someone enlighten me on this shimming the lifter?
Are you shimming internally to limit plunger travel like a anti pump up?
If so can you describe how and what you do?

Thanks in advance

[GARY C]

What gains in dyno HP, MPH, RPM peak gains have you seen from shimming hyd flat tappet lifters on a stocker cam? Is it possible a hyd lifter with .400 lift @ the valve with 170 on the seat with 350 open with a agressive lobe could cause the lifter to collapse @ 6000 RPM.
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Based on your seat psi I assume your talking BBC?
Lifter brand, oil and lobe profile all play a part and with today's aggressive lobes I think lifter collapse would be very possible. Prior to the invention of minimal travel lifter the NHRA Top Stock guys were shimming stock hyd rollers from .200 plunger travel to .010 to deal with a .525 lift limited aggressive lobe. Way before that guys were setting hyd flat lifters near the bottom of the plunger travel for the same reason, I would try to shim before I would feel safe setting it at the bottom of the travel due to oiling issues.

[sjre]

Why even bother.Solids are now legal in stock.

[GARY C]

Why even bother.Solids are now legal in stock.

What does that have to do with then?

[1972ho]

Yea just buy some solid lifters problem solved.

[vortecpro]

My testing showed, with a hyd flat tappet lifter shimmed to have .010 travel with an aggressive lobe .398/466 lift @ the valve with 170/350 spring pressure. HP went up 12 HP, power was carried further out, the HP graph cleaned up and the engine was happier.

[GARY C]

My testing showed, with a hyd flat tappet lifter shimmed to have .010 travel with an aggressive lobe .398/466 lift @ the valve with 170/350 spring pressure. HP went up 12 HP, power was carried further out, the HP graph cleaned up and the engine was happier.

Does anyone make a minimal travel hyd flat lifter? It seems they would with the modern day aggressive lobes.

[vortecpro]

I don't think they do, but I do...now, another learning experience. Keep in mind my lobe looked like a square.

[GARY C]

I don't think they do, but I do...now, another learning experience. Keep in mind my lobe looked like a square.

Are you going to have enough time on this engine to determine lobe life? My understanding of the old school method of setting the lifter at the bottom shortened lobe life, it would be interesting to see what effect a minimal travel will have..

[vortecpro]

The only reason I didn't put a solid lifer with lash on this cam was it ran for years with these hyd lifters and was in good shape, I didn't want take the chance of destroying the cam by putting new lifters on it. Another thing to note was this cam had VERY aggressive lifter rotation, never seen that before. The cam is in a race car, hopefully it will live, Ill let you know if theres a problem.

[tenxal]

Does anyone make a minimal travel hyd flat lifter? It seems they would with the modern day aggressive lobes.

Cliff Sherman supplies modified Delphi hydraulic lifters for SB/BB Chevys. I've used them and they'll rpm to at least 7,300-7,400. They have a tool steel foot on them. Many cam companies offer a similar style lifter which they call either a reduced travel or limited travel lifter. The nomenclature gets a bit herky here as to the actual characteristics of the lifter so you'll want to have that conversation with the lifter mfg.

The Sherman/Delphis are really good pieces.

Trend, PPPC and others offer a 'low movement' lifter which is just a solid lifter with a spring under the push rod cup....no hydraulic metering.