LS Hydraulic lifter limitations

[Rob Wright]

Stock LS7 lifters have the best dynamic stability out of any I've tested, and the earlier-version LS7 lifters with circlip axle retention are the ones to have.

Differences in stability of stock vs aftermarket brand "M" and aftermarket brand "J" is not incredibly significant.....Best to worst (stability-wise) is listed in order and again, they are not vastly different. All of this assumes plunger at mid-travel for preload.

Actually in my experience the WORST performing hydraulics (stability, , on a given cam/spring/rocker/pushrod combination) were limited travel units.

If you're hitting a wall at 7000 RPM, you should look at whether you have TOO MUCH spring force (compressing the lifter plunger isn't necessarily the problem.....), too heavy retainer, spring, rocker, or all three, and more often than not the cam lobe geometry itself.

Proper lobe geometry shouldn't require tons of spring force to run well past 8K RPM if it is packaged with light valves (like stock LS) a light rocker (like the stock LS), retainer (again, stock LS), and spring (like beehive or well thought out dual like PSI LS 1512 ML), along with a pushrod that is stiff enough to avoid deflection/energy storage/energy release. This sequence causes bounce at closing and that's when stuff breaks.

[e vassar]

Originally Posted by Rob Wright

Stock LS7 lifters have the best dynamic stability out of any I've tested, and the earlier-version LS7 lifters with circlip axle retention are the ones to have.

Differences in stability of stock vs aftermarket brand "M" and aftermarket brand "J" is not incredibly significant.....Best to worst (stability-wise) is listed in order and again, they are not vastly different. All of this assumes plunger at mid-travel for preload.

Actually in my experience the WORST performing hydraulics (stability, , on a given cam/spring/rocker/pushrod combination) were limited travel units.

If you're hitting a wall at 7000 RPM, you should look at whether you have TOO MUCH spring force (compressing the lifter plunger isn't necessarily the problem.....), too heavy retainer, spring, rocker, or all three, and more often than not the cam lobe geometry itself.

Proper lobe geometry shouldn't require tons of spring force to run well past 8K RPM if it is packaged with light valves (like stock LS) a light rocker (like the stock LS), retainer (again, stock LS), and spring (like beehive or well thought out dual like PSI LS 1512 ML), along with a pushrod that is stiff enough to avoid deflection/energy storage/energy release. This sequence causes bounce at closing and that's when stuff breaks.

Robin where is a good source for the PSI LS1512ML? What about a beehive?

[SSDiv6]

Originally Posted by e vassar

Robin where is a good source for the PSI LS1512ML? What about a beehive?

Ken Juszczyk at Motorsports Unlimited

https://www.motorsportsunlimited.net/

or

Brian Benson at Dakota Parts Warehouse

http://dpwferreavalves.com/

[Mike Taylor 3601]

I just saw this post... most likely you need more spring and that may fix it,if does'nt have any bent valves... If it was mine, I would throw the hydraulics away, put solids in with .003-.007'' lash...
strongest pushrod,adjustable rocker and enough spring pressure..
I know saying things like that I will have LS'ers telling me how stupid I am.....but thats OK....

[Mike Mans]

Originally Posted by Mike Taylor 3601

I just saw this post... most likely you need more spring and that may fix it,if does'nt have any bent valves... If it was mine, I would throw the hydraulics away, put solids in with .003-.007'' lash...
strongest pushrod,adjustable rocker and enough spring pressure..
I know saying things like that I will have LS'ers telling me how stupid I am.....but thats OK....

Agreed with you Mike. If a solid roller lifter is an option in a performance based combination - I would never choose to run a hydraulic.

[e vassar]

The valve springs on the car were conventional spring with damper non adjustable rockers. The springs were a little weak...I wanted to go with single conical spring like the hemis have,but my engine guy said they're too tall for your valve stems, so I deferred to his judgement and going with new PAC springs with dampers. I only need to get another 4-500 RPM to get to the finish line. I plan on buying a "good" set of heads in the hopefully near future and will set them up with better stuff.