02Z28LS1

iTrader: (2)

so my heads were milled .040" while i was having them checked for warping/cracks & a bent valve replaced to get rid of a fire ring indent....i am also replacing the stock LS1 lifters with LS7 lifters, which from what i've gathered (with others posting measurements using dial calipers to back it up), are .050" taller, resulting in approximately .090" shorter clearance overall

the shop i had do the work (before they knew i had different lifters) said that i should be fine with the stock length pushrods with just a .040" difference, but i'm not convinced on that, given that many people on here have said that .050" shorter rods are needed when using the LS7 lifters.

.010" or .015", i could see as being negligible, and the stock pushrods would probably be OK....but .040" or .050"? not so much.

and definitely ~.090" as in my case with the heads + lifters? fuggedaboutit!

thoughts?

Burken01

iTrader: (88)

Buy a pushrod checker and check, it will take all the guess work out of it...

vettenuts

iTrader: (4)

LS7 lifter is a direct replacement for the LS1 lifter. No change in pushrod due to the lifters. But in the end, best to buy the adjustable pushrod rather than guess.

02Z28LS1

iTrader: (2)

yeah, i've already got the adjustable rod length checker and i plan on measuring....my main question, i guess, was whether or not .040" worth of milling is enough to warrant shorter pushrods, or if the stock length 7.4" rods would work?

i would think i would need to go down to either a 7.375" or 7.35", assuming a .040" decrease in head height, all else being equal?

JustAFooL

iTrader: (45)

Just check. Your guesses are probably close though.. For some reason, when I installed my LS7 lifters, I was thinking there was a difference in height. Vettenuts is the man on this stuff though, I'm sure he knows what he is talking about on this stuff.

03Sssnake

iTrader: (20)

^^^yep, agree with these guys. Remove all doubt, pr checker is the only way. I had 7.4s on hand when I did my H/C swap (milled 243s), but they ended up being a little too long, ended up going with 7.375s.

02Z28LS1

iTrader: (2)

OK, guys....i'm going to check...i've already stated that, & that's not my issue/question.

let me rephrase the question another way:

would a difference in height of .040" absolutely require a shorter pushrod, or would a stock-height 7.4" pushrod work fine in that scenario? this is with stock everything, rockers, springs, valves...the only thing not going back in from what was already in the car is the LS7 lifters.

if there's more to it than just a yes or no answer, can anyone explain why they might work in one scenario with a .040" difference, but not in another?

how much were your heads milled?

Old Geezer

iTrader: (3)

You seem intent on ignoring what others have suggested. So a simple answer: If you want to add .040 to the lifter preload, then use the stock rods...

garygnu

you can order push rods in .025 increments.its best to have proper lifter preload for valve train longevity.

LilJayV10

iTrader: (39)

He isn't asking if he should check, it seems that he is. He's asking if .040 off would negate shorter pushrods. Nothing more, nothing less.

I'm going to say yes it would, My heads were milled from 64cc down to 59cc, I can't remember how much were taken off but around .040-.050 sounds right. With a small EPS cam I ended up w/ 7.350 pushrods, in a stock application Geoff says 7.40 would be fine.

JustAFooL

iTrader: (45)

And there is no real answer to his question unless he checks. Every single application is different, when I went from my stock heads to my patriots which were also milled to 59cc, I went from factory pushrods to 7.3 while keeping the same cam. When I called to order, TSP said there was no way. I went with what I measured and 500 miles later, car runs and sounds great.

So what IM saying is, any little change can NEGATE changing pushrods for proper preload. MEASURE.

LilJayV10

iTrader: (39)

I agree 100%.

02Z28LS1

iTrader: (2)

well, it turns out that i was wrong about the amount of milling....instead of .040", it was .004"...had bad reception on the cell phone at work when talking to the shop, and i heard "forTY" thousandths instead of "FOUR" thousandths....

03Sssnake

iTrader: (20)

I told them .020, but I suspect they took a little more off. 7.4 was a little too much pre-load for comfort, also used GM MLS gaskets.