what is the stock preload?
Different for each car, but mine was ~.100 - .110
Although take this with a grain of salt, as this was measured with an aftermarket cam inplace, and simply added the difference between base circles and pushrod lengths.
Although take this with a grain of salt, as this was measured with an aftermarket cam inplace, and simply added the difference between base circles and pushrod lengths.
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Originally Posted by WS6FirebirdTA00
ok got ya, im gettin some new ones for my f13, did you see my other post where i only have about 0.030" preload with damn 7.4's?
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Originally Posted by bigredexpress99
There is no preload specs, you simply torque them down to 22 ft/lbs. 
I am assuming he wants to mimic what ever the factory results are...
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Originally Posted by torchredfrc
There must be some guidance on preload... this is expecially important when milling heads down so that the preload range on the lifter isn't exceeded.
https://ls1tech.com/forums/generation-iii-internal-engine/465866-comp-lifter-preload.html
Crane recommends a deeper set, I think when you follow their procedure you end up with around 0.120" of preload. I just got my Morels, and everyone I have spoken to has told me with the 0.030 preload they are quiet.
Are you measuring the preload with a dial indicator at the pushrod during the tightening procedure? That is what really needs to be done to get the numbers from the factory.
Are you measuring the preload with a dial indicator at the pushrod during the tightening procedure? That is what really needs to be done to get the numbers from the factory.
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From: North Carolina
I check mine with a comp cams PR checker, I tighten everything down, extend it so there is no rocking play in it and add 0.080-0.120 for preload. This is how I was told to do it.
Originally Posted by HALLZ
Personally I listen to Crane once about pre load and it cost me $$ and a hole lot of time and frustration!!
Listen VHP before Cane's so/so tech support regarding LSx (JMHO)
Listen VHP before Cane's so/so tech support regarding LSx (JMHO)
Take the base circle of the stock cam, the base circle of the new one, and subtract. Let's say that the base circle is .100 smaller. That means the radius is .050 less, which equals that much less preload. So if the "actual" length of the stock pushrods measure out to be 7.400 and the new ones measured out to an actual 7.450, then your preload will stay the same. This is what I plan to do when I get my cam. I am also gonna use the paint on the valve stem to verify that the pushrod length is correct. You want the paint to be removed off the center of the stem. Too high or too low would mean either too short or too long of a pushrod.
Stock can be .050 to .200 from what I've measured. When we do our Cams about 90% of the time we have to use 7.350 pushrods.I personally like .040-.080 preload on stock lifters.
As for the Morels --do not put .100 preload on those. You want .020-.040 preload which is like 1/8 -1/4 turn.
As for the Morels --do not put .100 preload on those. You want .020-.040 preload which is like 1/8 -1/4 turn.
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From: North Carolina
Originally Posted by BriancWS6
Take the base circle of the stock cam, the base circle of the new one, and subtract. Let's say that the base circle is .100 smaller. That means the radius is .050 less, which equals that much less preload. So if the "actual" length of the stock pushrods measure out to be 7.400 and the new ones measured out to an actual 7.450, then your preload will stay the same. This is what I plan to do when I get my cam. I am also gonna use the paint on the valve stem to verify that the pushrod length is correct. You want the paint to be removed off the center of the stem. Too high or too low would mean either too short or too long of a pushrod.
Originally Posted by WS6FirebirdTA00
i wouldnt do it that way, with new heads, head gaskets and what not it will change the value a good bit.
In the case of new heads/gaskets then the paint method would still work as far as too short/too long of the pushrod length.
Another way to look at it is this.....how much are the heads milled? How thick are the gaskets being used? Lets say that you were using a set of heads milled .030 and a .010 thinner gasket, then that is a total of .040 shorter pushrod needed. So lets say after running the setup that I mentioned earlier, and finding out these variables on the new heads/gaskets, I would order up a set of 7.400s to replace the previous 7.450s.
I called 4 places today to inquire about this...I will be running Lunati 72432 lifters, AFR heads milled .024 (cometic .040) and the F13 cam. Here is what I found out:
Thunder said .060-.070 w/Heads/Cam Cars and stock is .080-.090
Texas-Speed said .020 (they also recommended to use Lunati Specs)
Lunati said .030-.040
AFR said .100
I got ranges from .020 all the way up to .100. I think I'll go somewhere around .030-.050 based on the answers I received.
Thunder said .060-.070 w/Heads/Cam Cars and stock is .080-.090
Texas-Speed said .020 (they also recommended to use Lunati Specs)
Lunati said .030-.040
AFR said .100
I got ranges from .020 all the way up to .100. I think I'll go somewhere around .030-.050 based on the answers I received.
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From: North Carolina
it also depends on the valves in the new heads as well if they are differnt sizes. i will stay in the recommended range of thunder and AFR as those guys know their **** and build motors a LOT that make killer power.