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Old 04-23-2010, 12:29 AM
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rockers are nearly bottomed out

I have trick flow 195 heads and scorpian 1.5 roller rockers. When I set the rocker onto its stud without the pushrod im darn near at correct geometry just a tad on the inside. which is about 7 5/8" from cup to cup, and the proper length pushrod is 7 3/4"... Im using a hydraulic flat tappet cam and when I swaped in solid lifters to meassure the piston to valve clearence the rocker was bottomed out on the stud because the pushrod seat on the solid lifter is about 1/8" shorter then that of the hydraulic.

will my hydraulic lifter compress .125 during operation? will there be "flex" in the valvetrain that would also make me bottom out?

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Old 04-23-2010, 04:54 AM
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The info is in the Knowledge Base on this site,
http://www.hotrodders.com/kb/valvetrain-articles
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Old 04-23-2010, 12:24 PM
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Quote:
Originally Posted by 48Frankin
I have trick flow 195 heads and scorpian 1.5 roller rockers. When I set the rocker onto its stud without the pushrod im darn near at correct geometry just a tad on the inside. which is about 7 5/8" from cup to cup, and the proper length pushrod is 7 3/4"... Im using a hydraulic flat tappet cam and when I swaped in solid lifters to meassure the piston to valve clearence the rocker was bottomed out on the stud because the pushrod seat on the solid lifter is about 1/8" shorter then that of the hydraulic.

will my hydraulic lifter compress .125 during operation? will there be "flex" in the valvetrain that would also make me bottom out?
No the plunger shouldn't do an eighth inch of plunging. A hydraulic should be no more than .060 and is best at .020.

You present an interesting issue of the hydraulic and the solid being significantly different heights, that should not be. Chevy production used the same push rod for both type lifters at 7.8 inches give or take a few thou.

Many aftermarket heads do not position the valve stem at the same installed height as GM production. You have to select a push rod that provides the correct rocker sweep on the stem and allows the rocker body to clear the retainer and spring as well as the stud boss. It is possible to buy lash caps if more stem length is required for these alignments and clearances. A lash cap on the stems will require a different length push rod for which you'll have to measure. A really good read on the subject with some diagrams is at the Comp Cams site http://www.compcams.com/Technical/FA...inGeometry.asp

Bogie
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Old 04-23-2010, 02:30 PM
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X2 boogie

are you sure that you have the right pushrod lenght, did you ever measure with a pushrod length checker to see exaclty what size pushrod you need
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Old 04-23-2010, 02:32 PM
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Thanks bogie, as long as I have the .060 clearence I should be fine? I also assume its fair to say that if the lifter compress it should be during the lift and not while the valve is closing?
lash caps never heard of such a thing... but then agian im a newb
I just find it kind of odd that brand new unmolested aftermarket heads would have such minimal clearence for roller rockers.

The pushrod cup on the solid lifter is diffently atleast .100 less then hydraulic in height... I assume its a chevy lifter anyway it fits into the bore just fine
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Old 04-23-2010, 02:37 PM
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yes i meassured
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Old 04-23-2010, 03:27 PM
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Quote:
Originally Posted by 48Frankin
Thanks bogie, as long as I have the .060 clearence I should be fine? I also assume its fair to say that if the lifter compress it should be during the lift and not while the valve is closing?
lash caps never heard of such a thing... but then agian im a newb
I just find it kind of odd that brand new unmolested aftermarket heads would have such minimal clearence for roller rockers.

The pushrod cup on the solid lifter is diffently atleast .100 less then hydraulic in height... I assume its a chevy lifter anyway it fits into the bore just fine
The push rod cup to the lifter base should be the same between the hydraulic and solid lifter. In an age of everything Chevrolet coming from China, you've got to measure and check everything, assumptions are totally out the window these days.

Many aftermarket heads come with valves that are .1 inch taller as installed. With a stock length pushrod this drops the rocker fulcrum.

Bogie
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