Rocker Ratios...variances
10-06-2015 | 04:58 PM
#31
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Joined: Nov 2004
Posts: 14,103
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From: On A Dirt Floor
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°
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°
The edit is that LSM ground the cam. They did not pick the cam. That was done from the engine designer.
10-06-2015 | 06:24 PM
#32
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Posts: 3,599
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From: taxachusetts
10-06-2015 | 10:12 PM
#35
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Joined: Apr 2004
Posts: 1,268
Likes: 239
From: Michigan
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
Don't want to hijack the thread I just had a brain fart reading that info Sorry
Last edited by abones; 10-06-2015 at 10:21 PM.
10-07-2015 | 02:00 PM
#36
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Joined: Jun 2012
Posts: 1,455
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From: OK CIty, OK
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
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
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.
10-07-2015 | 02:28 PM
#37
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Joined: Jun 2004
Posts: 7,317
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From: frankenmuth michigan
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!!
10-07-2015 | 09:14 PM
#38
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Posts: 6,019
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From: Grand Rapids, MI
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.
That gives me 0.734" IN lift and 0.680" EX lift.
Apparently I have been running 1.932's and 1.79's for years.
That gives me 0.734" IN lift and 0.680" EX lift.
Last edited by Rookie; 10-07-2015 at 09:19 PM.
