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Quote:

Originally Posted by SB (Post 4363050)

Performance 540cid Marine I/O

How would this work:
Custom Spec'd / Ground by LSM

Intake Duration at .050" = 226°
Exhaust Duration at .050" = 228°
Lobe Lift Intake = .300". With 1.7 Rockers = .510"
Lobe Lift Exhaust = .300" . With 1.7 rockers = .510"
Events at .050"
Intke Opens : -1° BTDC
Intake Closes 47° ABDC
Exhaust Opens 48° BBDC
Exhaust Closes 0° ATDC
ICL = 114° ECL = 114°
LCA 114°
Overlap -1°

I couldn't go back and edit this.

The edit is that LSM ground the cam. They did not pick the cam. That was done from the engine designer.

Quote:

Originally Posted by SB (Post 4363099)

I couldn't go back and edit this.

The edit is that LSM ground the cam. They did not pick the cam. That was done from the engine designer.

just looking at those specs and I know who designed it.

.300 lobe ? This engine have peanut port heads with smaller valves installed ?

No, quite typical 540cid performance build. Rectangular heads and the like.

This was the cam that was put in it.

So I know that I'm oldschool and out of touch with this new stuff so way back when we had to design our own engines. just sayin! many of us were engine designers ahead of our time! Pioneers

Don't want to hijack the thread I just had a brain fart reading that info Sorry

Quote:

Originally Posted by MILD THUNDER (Post 4362716)

snip

With that being said, I have no reason to doubt his procedure of this particular rocker arm test, or his knowledge of valvetrains. I am pretty certain, the man has learned valvetrain geometry basics, and how to use a dial indicator by now, considering he speaks at events like PRI, writes tech articles for engine builder magazine, etc. snip

Joe,
I'm certainly not trying to discredit the man's work, just trying to make sure the variances lie in the rocker arm itself versus other engine specific variables. Sorry if it came off that way.

Someone should model a big block assembly in SolidWorks (I'm sure it someone has, but I bet it won't be seen by us) as well as various components. Add in your cam lobe, valve spring installed height, rocker arm specifics and see how it cycles. I'm nearly positive one could generate all sorts of neat reports from the data. Alas, that level of precision would be time consuming as all hell to create.

Ok, back to bein a nerd.

I was shocked initially by the data, wondering how pushrod geometry played into the testing, going to assume it was set perfect, if so the numbers are a GOOD reason to avoid certain rocker arms!!

I just noticed they used Scorpion 1.7' and 1.8's.
Apparently I have been running 1.932's and 1.79's for years. :cartman:

That gives me 0.734" IN lift and 0.680" EX lift.