Ls9 powermax cam question

[Samspeed]

Hi everyone.
I’m in the process of an Lsa conversation on my ‘10 SS and was planning to do a cam swap and chose the ls9 powermax. Does anyone have any knowledge with this cam choice in the LS3? They recommend the pac1218 springs but the cam lift is .600” and the 1218 springs max is the same. Also would the stock Ls3 pushrod be okay to use? I also plan to use a 2.75” upper pulley and LT headers and a cai. Thanks for any help.

[Samspeed]

Sorry about the auto correct, I meant conversion.

[Nate2SS]

When doing any cam there are several things you might want to change. With my car I did a BTR Stage 3 cam with chromoly pushrods at stock length and BTR 660" springs. I would also recommend doing trunnion upgrade, as well as a LS2 timing chain tensioner as well as a cam plate.

The tensioner, plate, and trunnion upgrade are more preventative parts to make sure everything stays together. I did not do the trunnion upgrade but I plan on putting the set I bought in sometime soon.

Make sure you get a good tune to go with it. Plenty of remote tuners on this site if needed.

[Scott S]

Your also going to want bigger injectors, fuel pump or auxiliary fuel system with a ZL1 pump. LSA supercharger loves E85 also... Always measure for pushrods...

[1JEWLDSSRS]

Also not to forget, while you're in there and the front of the engine is apart, ya might want to upgrade your oil pump to a high volume Melling unit just for the added insurance. Wouldn't hurt.

[FASTFATBOY]

Put a 2.4 upper on it, you're gonna do it anyway. Put some ID 850 injectors in it and you also need a fuel pump. Always measure for pushrods, always.


I don't see the need for a trunion upgrade at .600 lift


I ran a .600 lift cam with the PAC 1218X springs with no issues.




Not mine, saved it years ago......


Here is the easy way to measure pushrods:




FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.

Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.

I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.

Here it is again in a nutshell:

1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.

For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...

I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.

If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.

THIS METHOD ALWAYS WORKS!!!

Check it using the above method and see where you are.

Thanks,

[Batmanntexas]

@FASTFATBOY - Thanks for posting that!! I have personally found it a serious PITA to use an actual pushrod length checker on LS motors....it could also just be me.

-Scott