I have a LQ4 with a EPS 226/230 cam. I currently run 7.425" push rods. I plan on putting a set of 243 heads milled 0.020" with 0.051" head gaskets on this engine. Plan on using LS7 lifters. What is the most likely pushrod length that I need? I plan on measuring but it would be nice to have the correct pushrod when I put the heads on.

 

Don't estimate, measure...

 

+1

inproper preload etc will make for a noisy valvetrain and possible failure. It's a $20 length checker, which is more? $20 checker, or a $1200 valvetrain?

 

If you want to have the correct pushrods then buy a bunch of sets, so once you measure the correct length you can put them in right away. Not ideal but it would guarantee no down time. If you order from Summit I think they do hassle-free returns. If it were me with your setup, I'd get 7.325-7.400 in 0.025" increments, so that's 4 sets you would buy.

 

I have the lunati pushrod checker if you need one,

 

Thanks Ferocity that was exactly the info I was looking for. Obviously saying I'm going to measure was overlooked by some. LOL.

 

So your gonna buy a set of each size, then measure and decide which to use? Then pay a restocking fee on all the sets you don't need?

 

Some people can't afford down time and must order many sets at ones. I'm fairly certain Summit does not charge a restocking fee. They offer a full refund within 90 days.

 

BS, if your gonna order a bunch of push rods, order them. Don't ask for a SWAG! What if he needs a mixed set? If your gonna order a bunch of sets and measure, why ask? Especially if you know Summit will take them back?

 

what throws most off from just doing the simple math is not knowing what the new cam base is vs the stocker most the time...for example my base is .050 smaller then a stocker..So if i was just to swap cams and new this info i could order the correct push rods with out even measuring..so i would need a rod of 7.43 instead of a stock 7.38 to get factory preload dead on..

you just got to know all the before specs and new specs of the parts an what effects height an how and you can get very close to what you need if not spot on.

 

hers a post from a thread that might help
https://ls1tech.com/forums/generatio...-question.html

From Shane at Thunder Racing
The TDC method is NOT always accurate. Try the EO/IC method to check
pushrod length. I have posted
directions on this forum numerous times... Here it is again:

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 lift
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.