sman

iTrader: (4)

What length should be required here?

lq9 shortblock
799 heads
EPS 230/234 .600/.601 112+4

EPS said 7.425 for a stock ls1, so I picked up a set of those. Also have a set of 7.400s from my previous setup.

When put in there doesnt seem to really be a difference between the two.

Thoughts? Put the 7.425's in and run it? I havent started it yet.

crainholio

iTrader: (2)

So instead of trusting EPS, you prefer advice from strangers with no demonstrable skill?

sman

iTrader: (4)

EPS gave their recomendation based on a stock LS1, which is clearly stated in the first post, along with the fact that I do not have a stock LS1.

crainholio

iTrader: (2)

OK...you'd rather take uninformed guesswork over a $20 tool and precise measurements?

TransamGCS

iTrader: (2)

Get a comp cam push rod length checker, there are several write ups that tell how to use it, length of pushrods can be different based on the cam, rockers, and lifters and the lifter pre load.

sman

iTrader: (4)

No, I was hoping for some information, such as your motor assembled will have the same dimensions as an assembled ls1. So EPS recommendation of the 7.425s would stand correct. Or "the deck on your block is slightly taller than an ls1, so you would probably be correct in using the 7.4s...."


I will order a PR checker then. For as close as this was I wasnt sure if it was enough to matter or not.

ZeeOSix

If EPS says that a bone stock LS1 takes 7.425" pushrods, then they are probably wrong with any other "recommendations". Better get the pushrod length checking tool.

sman

iTrader: (4)

Why is that? A stock ls1 uses 7.4s, their cam has a slightly smaller base circle requiring a little longer pushrod, ie the 7.425s. How are they wrong?

ZeeOSix

Maybe I'm reading your stuff wrong, but it makes it sound like EPS is saying stock LS1s have 7.425" pushrods. Fact is all bone stock LS1 and LS6 engines use the same length pushrods ... 7.400".

But now you elaborate that your cam has a smaller base circle, and if that was the only change then yes, you would need longer pushrods.

Did you at least try to determine how many turns the rocker arm bolt went from zero lash to 22 ft-lbs of torque?

sman

iTrader: (4)

Yes, thats my bad. Re reading it, it does sound like thats what I was saying, but its not what I meant. I could have worded that better I suppose.

From what I was told, EPS cams have a slightly smaller base circle, but that again was part of my post, to confirm, or deny that.

Its closer to 1 turn with the 7.425s and almost 2 with the 7.4s.

ZeeOSix

Sure it's not the other way around? The longer the pushrod, the more turns you will see on the rocker bolt when going from zero lash to 22 ft-lbs.

crainholio

iTrader: (2)

That's a fact. Once you get beyond the stock gross lift you have to reduce the base circle of the lobes, or the cam won't fit past the bearings.

Even the factory LS6 cam with only 0.551" gross lift had to be ground on a smaller base circle for this reason according to Hib Halverson's article.

sman

iTrader: (4)

Good info! Thanks!