stangkiller2005

iTrader: (15)

what size push rods are you using? im using stock length.. but have heard that they are to short, and throws off lifter pre-load... just wanted everyones oppinion..

thanks!

to-fst-4u

iTrader: (35)

im runnin 7.400 Comps in mine

stangkiller2005

iTrader: (15)

hows your valvetrain noise? not to loud? mines louder than stock now.. but i kno that happens wen a bigger cam is installed

to-fst-4u

iTrader: (35)

hahahaha. its been so long since ive drove a stock cammed car that i dont know what the valvetrain sounds like in one. its not too loud but deffinately noticable. i just over look it now dont bother me anymore.

brad8266

iTrader: (23)

There is no opinion in this, it is simple mechanics. If you want the same preload as stock but your new cams base is much smaller than the stock cams base then you will need to make up for the smaller base with longer pushrods.

I have an XE lobed cam and I measured the base of it and it is 1.450, the stock cam is 1.553, so by going from a stock cam to my XE lobed cam I would need a pushrod that is .0515 longer than my stock pushrods in order to keep stock preload. Stock rods are about 7.39 so add .0515 to that and you get 7.4415.

Your magic stick has an even smaller base circle (XE-R lobes) than my XE lobes so you would need a slightly larger rod than I do. Your 7.4 rods you are using now are probably reducing your lifter preload by around .050 which is way too much preload to lose. You likely have very little to any preload running a cam like that with 7.4 rods.

to-fst-4u

iTrader: (35)

im just running these pushrods per Jon at Texas-Speed. Im running their heads and cam and these are the pushrods that he reccommended. so from what your saying a 4.450 pushrod would be a better choice so i wouldnt lose as much preload?

brad8266

iTrader: (23)

Exactly 7.450 would work, I would always double check though with a pushrod length checker to get the exact length needed.

Running a 7.4 on a XE-R lobe with stock heads/gaskets is laughable.

stangkiller2005

iTrader: (15)

soooooooo anyone wanna trade my 7.4s for your 7.450s ???

to-fst-4u

iTrader: (35)

so with me running the PRC stage 2.5 5.3 heads with the stock GM gaskets...would i need to run 7.400 or 7.450?

brad8266

iTrader: (23)

I would definetly use the PR checker in your situation since you have swapped heads and there could possibly be variances. The checker is really fast and easy to use and will tell you what you need. All you do is take the measurement with the checker and then add about .075 to that number to account for proper lifter preload and then you have the PR length you need.

to-fst-4u

iTrader: (35)

ok i got you. i understand the reason Jon at texas speed wanted me to run 7.400 now. the 5.3 heads raise the compression, meaning that they have been decked more than a stock ls1 head correct? with the head per say being shorter, makes up the difference from the lifter to the rocker arm, where as on a stock headed MS3 car u would use 7.450 and in my case, 7.400.

brad8266

iTrader: (23)

No the heads arent decked on 5.3L heads i dont believe. The chamber itself is designed differently which is where the smaller chamber volume comes from.

But yes if a head is decked you can shorten the PR, I run 7.4 on my setup because I have decked heads and thin head gaskets.

Lurius

iTrader: (7)

Not to hijack, but would this mean a 408 with 317 heads would use 7.450" pushrods with an ms3 as well?

-Lurius

to-fst-4u

iTrader: (35)

gotcha. thanks man.

brad8266

iTrader: (23)

In any aftermarket or reassembeld top end I would just always use the checker, it tells the truth everytime as long as you use it properly.

For $20 and 30 minutes of your time it is well worth knowing you got the right parts in there.

to-fst-4u

iTrader: (35)

as long as they havent been decked and u are running the stock GM head gaskets. right brad?

brad8266

iTrader: (23)

Pretty much yes but like i said above i would use the checker on that since it is probably built block without the original heads.

Lurius

iTrader: (7)

Thanks you two, i'll be ordering a pushrod length checker next then! This is why I love this forum. Smart people, friendly people.

thanks again!

-Lurius