Lifter Pre-load
05-17-2009, 03:42 AM
#21
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One more question about the lifters, what's the difference between stock LS1, LS7 and GM Racing CTS-v lifter, performance and spec wise? I wanna know which lifter to go.
According to Pred-Z, LS7 lifter cup is ~.060 higher than original LS1 lifters. If my math was right, with my XE-R cam, 61cc 5.3L head, GM MLS and stock LS1 lifter with .060 preload, 7.425 pushrod should work. I'll measure it of course, pushrod checker already ordered.
According to Pred-Z, LS7 lifter cup is ~.060 higher than original LS1 lifters. If my math was right, with my XE-R cam, 61cc 5.3L head, GM MLS and stock LS1 lifter with .060 preload, 7.425 pushrod should work. I'll measure it of course, pushrod checker already ordered.
05-17-2009, 06:57 AM
#22
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The LS7 is GM direct OEM replacement lifter as we speak. It is what you want to run for the size cam you have. If you have ported 5.3L heads at 61cc, they must be milled. If they are milled and with LS7 lifters that have a higher cup (~.060) than original LS1 lifters you'll find that 7.425s are too long.
Simple calculation (not accurate but to give you an idea)
XE-R lobes have a smaller base circle (~1.455)
Stock base circle (1.55)
Differrence between the two .045. Take 1/2 of that as effective radius .0225
So just based on the cam you need .0225 longer p-rods.
Now to the heads: milled to 61cc so that is about .015
now .0225-.015= .0075 longer p-rods.
Now take into account the lifter LS7
.0075 - .060 = -0.0525 SHORTER p-rod
Stock length 7.400 + (- .0525) = 7.3475
Right there it gives an idea that your 7.425s will be too long. The calc above is not accurate that is why you have to measure also I did not take into account the variation of the Harland Sharp rockers Vs stock rockers.
Only 1 way to get the correct size for your setup. Measure at 0 lash on cam base lobe then add preload you desire and that will be your p-rod length.
Simple calculation (not accurate but to give you an idea)
XE-R lobes have a smaller base circle (~1.455)
Stock base circle (1.55)
Differrence between the two .045. Take 1/2 of that as effective radius .0225
So just based on the cam you need .0225 longer p-rods.
Now to the heads: milled to 61cc so that is about .015
now .0225-.015= .0075 longer p-rods.
Now take into account the lifter LS7
.0075 - .060 = -0.0525 SHORTER p-rod
Stock length 7.400 + (- .0525) = 7.3475
Right there it gives an idea that your 7.425s will be too long. The calc above is not accurate that is why you have to measure also I did not take into account the variation of the Harland Sharp rockers Vs stock rockers.
Only 1 way to get the correct size for your setup. Measure at 0 lash on cam base lobe then add preload you desire and that will be your p-rod length.
05-18-2009, 02:18 AM
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Now back to my previous question. If I measure using a checker lifter (solid lifter), I've to take it out afterwards. So when I torque the head to 22ft lb, should I do the two pass of 90* turn?
05-23-2009, 09:58 PM
#25
The LS7 is GM direct OEM replacement lifter as we speak. It is what you want to run for the size cam you have. If you have ported 5.3L heads at 61cc, they must be milled. If they are milled and with LS7 lifters that have a higher cup (~.060) than original LS1 lifters you'll find that 7.425s are too long.
Simple calculation (not accurate but to give you an idea)
XE-R lobes have a smaller base circle (~1.455)
Stock base circle (1.55)
Differrence between the two .045. Take 1/2 of that as effective radius .0225
So just based on the cam you need .0225 longer p-rods.
Now to the heads: milled to 61cc so that is about .015
now .0225-.015= .0075 longer p-rods.
Now take into account the lifter LS7
.0075 - .060 = -0.0525 SHORTER p-rod
Stock length 7.400 + (- .0525) = 7.3475
Right there it gives an idea that your 7.425s will be too long. The calc above is not accurate that is why you have to measure also I did not take into account the variation of the Harland Sharp rockers Vs stock rockers.
Only 1 way to get the correct size for your setup. Measure at 0 lash on cam base lobe then add preload you desire and that will be your p-rod length.
Simple calculation (not accurate but to give you an idea)
XE-R lobes have a smaller base circle (~1.455)
Stock base circle (1.55)
Differrence between the two .045. Take 1/2 of that as effective radius .0225
So just based on the cam you need .0225 longer p-rods.
Now to the heads: milled to 61cc so that is about .015
now .0225-.015= .0075 longer p-rods.
Now take into account the lifter LS7
.0075 - .060 = -0.0525 SHORTER p-rod
Stock length 7.400 + (- .0525) = 7.3475
Right there it gives an idea that your 7.425s will be too long. The calc above is not accurate that is why you have to measure also I did not take into account the variation of the Harland Sharp rockers Vs stock rockers.
Only 1 way to get the correct size for your setup. Measure at 0 lash on cam base lobe then add preload you desire and that will be your p-rod length.
I have TEA 243 Heads Milled to 61cc with a XE-R 224/230 Cam with Caddy Race Lifters and a GM MLS Gasket I have my Pre Load set to .065 on the lifers with HS 1.8 rockers and I had to run the 7.350 Push rods and 42# Greentops
Here is a Video of my setup
