I was told that I may have the wrong length in mind for what im doing. I plan to get the 228r cam from tsp and the prc spring kit. I was going to get the normal 7.4 pushrods, is this correct? I don't understand why I would need a different size when im not changing heads or anything. Thanks

 

I went with 7.425 pushrods when I did my cam, but I was told 7.4 was fine, someone correct me if i'm wrong.

 

bigger cams than stock use a smaller base circle. therefore you need a little longer pushrod or else your lifter preload will be too low. the preload needs to be between .060 and .100.

 

Checking the geometry is the only way to really tell.

Install a intake and exhaust pushrod and mark the valvestem. Just color it with a marker. Torque down those two rockers and turn the engine over and observe where your rocker is rubbing on the stem. It will remove the ink. As long as your're on the center most area of the valve stem, you're good.

 

So basically its better to get a 7.425 when your changing cams to a mild or big size?

 

Very good tip !!

 

Get a pushrod length checker. That's the only way to be sure you are using the corrrect length. Not all mid size cams need a longer pushrod. I have an LS1 that has a 224/228, 581/588 and it uses a 7.400 pushrod with stock heads and stock gaskets. Here is something to think about. If you go to a longer pushrod, without checking for the correct length, and your engine didn't really need longer ones you may bottom out the lifter plunger. When this happens, you're going to tear some **** up and have to go back into the engine. A length checker is less than $25 and is cheap insurance. There are several articles and post on how to use them.

 

This is not correct. On an LS1 with a fixed fulcrum rocker, the pushrod will not change the wipe pattern you must use shims to correct the wipe (geometry). As for pushrod length, this determines lifter preload and you should use an adjustable pushrod. Not sure why this isn't standard practice, the tool is under $25 and it eliminates buying two pushrod sets like a lot of guys do.

 

Using the right p-rod length will reduce valvetrain noise, correct preload (to avoid instability at higher rpms).
Correct procedure:
1- Setup geometry (centered)
2- measure p-rod length needed via checker.

(from experience, yes 7.425 p-rods are better in a cam only application on those XE-R lobes)

 

I thought you use the length checker when you have the cam in hand though.. So how would you know what pushrods to get with a cam package if you don't have the camshaft yet..?

 

Contrary to common belief (and internet lore), pushrods are the last part you buy after the motor is together enough to get an accurate measurement. And this is after the rocker geometry has been established as shims will affect the final pushrod length. Pushrods can be gotten in as little as two days, plan your re-assembly around their arrival. I usually do the measurement then proceed to re-installation of the water pump, radiator, etc. while waiting for them to arrive. They usually come in before I need them.

 

Yea.. but how am I suppose to do that if im getting a cam package from tsp? Cause you choose pushrods and springs then so if the cam is coming in a package with them then how would I know ahead of time how the measurements will be?

 

From xperience this is how it goes in your case: XE-R lobes
7.400 >> a bit noisy (low preload on certain motors)
7.425 >> less noise (preload between .080>.100)

This is relative to lifter used.

 

Contrary to the internet hype and misinformation, I just went to a 0.030" preload and my valvetrain is actually quieter than before.

Don't beleive everything you read...

 

You don't so leave out the pushrods or talk to TSP and see if they will deliver them after you measure as a separate item. They are pretty easy to work with and I would think would help you out. Get the adjustable pushrod from them for now.

 

Hi Alchemist, nice to see you over here too Like the alchemist said, having a longer pushrod doesn't actually give you a quieter valvetrain. I'm actually in the process right now of changing out my 7.4's for a set of 7.350's as I have too much lifter preload. Right now I have .125 of lifter preload and to me that's scary since some gm lifters only have .150 of plunger travel. I was told by knowledgible valvetrain experts that .25-.050 lifter preload is ideal. Just remember, if you're using the LS7 style lifters, the plunger height is higher than a standard LS1 lifter so naturally all things the same, you're going to have more lifter preload with the LS7 lifters than the stock lifters that came in your LS1.

 

Perhaps giving all the info will help,
1- What lifters?
2- What gaskets?
3-Heads milled?
4- What cam base circle?
5- (and to be ****) was your block decked?

Because believe it or not, you are posting on net as well so with your theory; your info can be hype and missinformation as well

 

Alright, ill just talk to tsp to separate it up until I measure the size. Yea this is stock lifters, everything is stock internally except the pushrods and springs ill be changing with the cam. So this shouldn't be to difficult

 

See that's internet math, and I'm a scientist.... as much theory as you want to throw out, until you perform the experiment (actually measure the length you need), all of the math you cited means nothing.

Who cares what lifters you are using...
It doesn't matter the gasket thickness
Heads milled, again, it doesn't matter,
Cam base circle, again, it doesn't matter.
Block decked, nope, doesn't matter anyways.... WHY

Because I actually measured at what point I had zero preload, then added the amount of preload I wanted, and came up with a length.

Stop doing the math, and actually buy the checker (or borrow your buddy Andy's checker) and actually measure what the length should be.

It's like the mice that what someone to pick out a magical camshaft based off less than 50 words of information about their setup, and then wonder why the car runs like crap... but it's a magical stip, or a hurricane cam, or a monster cam, or a bigfoot cam. To get a correct setup takes measurements and data.

Sorry, I'm a scientist, I checked my political correctness at the door when I got my degree.... actually it was after I blew something up for the first time because someone else said "IT SHOULD WORK".

The internet hype I'm talking about is that you need to run between 0.060 to 0.100 preload for a quiet valvetrain. I got the suggestion to try a shorter preload, and it worked.

 

Yes I agree,
BUT, if any engineer had to mock assemble his project before he calculates it on paper, there will be a lot of waisted resources.

Motors are applyied physics which work on tolerances and math.

I do not want to get into a pissing match about this with you, but your comments on that nothing matters but measuring is shaky. Measuring confirms your parts are fitting, however you have to know the parameters of your parts to confirm that your measurements are correct.

There is a reason why .030 works for ya, and as a scientist you should know why!

I'll make it simple, OEM preload is quiet and is in the .100 range, reduce that to .030 and all your valvetrain will go to S**T .
Again, there is a reason why .030 works for your combo, and obviously you do not know why.

In a XE-R lobed cam only application with original OEM valvetrain you WILL require longer p-rods to make up the difference in cam circle effective base radius.
Aftermarket 7.400 are actualy longer than 7.400 (stock p-rods are shorter). 7.400 is not an actual guage measurement.

And when it comes to using a checker, you measure at 0 lash and then ad preload to your measurement to come up with p-rod length needed. How do you know what preload your lifters tolerate?
Also OEM rockers are NON adjustable, so p-rodlength is usualy chosen on the smaller side without going over .100. They do not fit in exactly. To just say I set them at .030 make me think you have adjustable rockers.

The one thing that we agree upon is that you have to measure, but you also have to know all the parameters of the parts you are dealing with to make the correct choice.