Lunati/Morel 72532 lifters: check my pushrod length?
05-20-2012, 12:00 PM
#1
Lunati/Morel 72532 lifters: check my pushrod length? I installed a set of 72532LUN link-bar lifters, the high RPM Morel units w/ big roller wheels and polished bodies.
Measured pushrod length with a Comp tool carefully, got 8.5 turns on the tool to zero lash. I ordered 7.250" pushrods to get 0.025" preload.
math:
(8.5 * 0.050) + 6.800 = 7.225" to zero lash
I also double-checked my pushrod length during installation: just a few degrees more than 1/2 turn of the rocker bolt from zero lash to bolt hand tight (before torquing to 22 lb/ft).
I realize that the Morels have the pushrod cup higher than GM lifters, and that the LS6 cam's lobes are likely a larger base circle than most larger aftermarket cams...but these pushrods seem mighty small.
Anybody see anything wrong w/ my measurements or preload selection for these lifters?
Measured pushrod length with a Comp tool carefully, got 8.5 turns on the tool to zero lash. I ordered 7.250" pushrods to get 0.025" preload.
math:
(8.5 * 0.050) + 6.800 = 7.225" to zero lash
I also double-checked my pushrod length during installation: just a few degrees more than 1/2 turn of the rocker bolt from zero lash to bolt hand tight (before torquing to 22 lb/ft).
I realize that the Morels have the pushrod cup higher than GM lifters, and that the LS6 cam's lobes are likely a larger base circle than most larger aftermarket cams...but these pushrods seem mighty small.
Anybody see anything wrong w/ my measurements or preload selection for these lifters?
05-20-2012, 01:02 PM
#4
If you measured correctly just like you said, you have nothing to be worried about. Items such as the lifters, the cam, milled heads, milled deck, and rockers can impact over length for the pushrods. You need to consider your lifters are different than stock and you are using considerably less pre-load than what people set GM lifters too.
I wouldnt be worried. I'm not a fan of half turn this or half turn that to measure pre-load (Don't go by that)! Thats just a ball-park someone made up. You have to consider that margin of error PLUS the stretch/friction of the fastener and the accuracy of the torque wrench! This method is not an exact measurement
I would trust the push rod measurement tool.
Also, I'm pretty convinced most of the browers here haven't measured for pushrods before, checked PTVC, or degree'd a cam. So trust your gut more than the guys here. JMHO
I wouldnt be worried. I'm not a fan of half turn this or half turn that to measure pre-load (Don't go by that)! Thats just a ball-park someone made up. You have to consider that margin of error PLUS the stretch/friction of the fastener and the accuracy of the torque wrench! This method is not an exact measurement
I would trust the push rod measurement tool.
Also, I'm pretty convinced most of the browers here haven't measured for pushrods before, checked PTVC, or degree'd a cam. So trust your gut more than the guys here. JMHO
05-21-2012, 08:34 AM
#5
https://ls1tech.com/forums/showthrea...referrerid=183
My memory is goin to ****. I'll see myself out...
05-21-2012, 01:33 PM
#6
Curious on your preload. Not sure yours are the same as mine, but I ran mine at first at 0.040" and they were quiet but noisy on cold start. I have increased preload on my new setup to 0.050" and noticed they are now quiet on startup. I did speak to Morel on this (his son actually) and he was nervous running too light a preload in an all aluminum motor due to changes as the motor heats up.
Just for reference (and from my crappy memory as well) I seem to recall that with the additional length of the lifter and reduce preload requirements, the overall pushrod length shortens around 0.100" everything else being equal.
Just for reference (and from my crappy memory as well) I seem to recall that with the additional length of the lifter and reduce preload requirements, the overall pushrod length shortens around 0.100" everything else being equal.
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05-21-2012, 05:59 PM
#8
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Curious on your preload. Not sure yours are the same as mine, but I ran mine at first at 0.040" and they were quiet but noisy on cold start. I have increased preload on my new setup to 0.050" and noticed they are now quiet on startup. I did speak to Morel on this (his son actually) and he was nervous running too light a preload in an all aluminum motor due to changes as the motor heats up.
Just for reference (and from my crappy memory as well) I seem to recall that with the additional length of the lifter and reduce preload requirements, the overall pushrod length shortens around 0.100" everything else being equal.
Just for reference (and from my crappy memory as well) I seem to recall that with the additional length of the lifter and reduce preload requirements, the overall pushrod length shortens around 0.100" everything else being equal.
I dont use gauge length method or neither the turn thing.I use the overall length wich require a dial caliper and some blade type filler gauge.You get more precise measurement.
05-22-2012, 04:22 AM
#10
I am embarrassed to say I don't remember. Would need to check the photos I have of them during installation. I did get them a number of years ago and it was just before they introduced the link bar version, which I would have preferred over using the trays.
06-14-2012, 06:14 AM
#14
Update: I fixed my laptop and recovered my notes w/ the following:
exhaust measurement was 8.25 turns cold... 7.250" pushrod yields 0.037" preload.
intake measurement was 8.5 turns cold...7.250" pushrod yields 0.025" preload.
Camshaft is a GM '02 LS6 piece purchased new. I measured four intakes, four exhausts, got same pushrod measurements...intake base circles are slightly smaller than exhaust.
I opened the engine and installed Trend 7.275" pushrods on the intakes to increase the cold preload to 0.050". Rocker bolts were just over 3/4 turn to snug, little less than 1/4 turn from there to 22 lb/ft torque. Left the exhausts as they were, with 7.250" rods in place.
The engine previously had a very slight click/tap at hot idle (32psi oil pressure) and it's nearly gone now. The noise was nearly impossible to hear unless there was a reflective surface next to the car to bounce it back...like stopped at a red light next to another vehicle.
I'm now considering options for the exhaust side. The remaining 7.275" pushrods will yield 0.0625" preload which may be fine based on other posts from reputable sources here, or maybe shell out for a set of 8 custom length ones to get it right on 0.050" preload. Decisions, decisions...
exhaust measurement was 8.25 turns cold... 7.250" pushrod yields 0.037" preload.
intake measurement was 8.5 turns cold...7.250" pushrod yields 0.025" preload.
Camshaft is a GM '02 LS6 piece purchased new. I measured four intakes, four exhausts, got same pushrod measurements...intake base circles are slightly smaller than exhaust.
I opened the engine and installed Trend 7.275" pushrods on the intakes to increase the cold preload to 0.050". Rocker bolts were just over 3/4 turn to snug, little less than 1/4 turn from there to 22 lb/ft torque. Left the exhausts as they were, with 7.250" rods in place.
The engine previously had a very slight click/tap at hot idle (32psi oil pressure) and it's nearly gone now. The noise was nearly impossible to hear unless there was a reflective surface next to the car to bounce it back...like stopped at a red light next to another vehicle.
I'm now considering options for the exhaust side. The remaining 7.275" pushrods will yield 0.0625" preload which may be fine based on other posts from reputable sources here, or maybe shell out for a set of 8 custom length ones to get it right on 0.050" preload. Decisions, decisions...
